Construction of Topological Macromolecular Side Chains Packing

Article pubs.acs.org/Macromolecules

Construction of Topological Macromolecular Side Chains Packing Model: Study Unique Relationship and Differences in LCMicrostructures and Properties of Two Analogous Architectures with Well-Designed Side Attachment Density Li Han,†,‡ Hongwei Ma,†,‡ Yang Li,*,†,‡ Jian Wu,†,‡ Hanyan Xu,†,‡ and Yurong Wang†,‡ †

State Key Laboratory of Fine Chemicals, Department of Polymer Science and Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian Liaoning 116012, China ‡ Liaoning Key Laboratory of Polymer Science and Engineering, Dalian Liaoning 116012, China S Supporting Information *

ABSTRACT: A new series of linear−comb and 4-arm star− comb side chain liquid crystalline polymers (Lc-/Sc-SCLCPs) have been synthesized and characterized. The treatment of hydride siloxane-containing terminated liquid crystalline and high 1,2-/1,4- (high vinyl, hv/low vinyl, lv) linear or 4-arm star polybutadienes (L-/S-PBs) was conducted via the methods in combination of living anionic polymerization and “reverse” hydrosilylation to obtain SCLCPs with wide mesomorphic temperature range (ΔT) and narrow polydispersity index (PDI). The possible molecular arrangement model of two analogous hv-/lv-architectures was constructed, that was used to systematically investigate the effects of Lc- and Sctopological morphology on liquid crystalline (LC) properties and molecular microstructures. SCLCPs exhibited the same smectic A phase around room temperature, but thermal properties were significantly different due to differences of interaction force resulting from different macromolecular side chains packing. Surprisingly, the trend of lv-SCLCP displaying the effects of topology on phase transitions and microstructures was just contrary to that of hv-topology. hv-Sc-SCLCPs containing high density mesogenic composition were desired to generate wider ΔT and higher molecular layer order in comparison with Lc analogues, which provided a unexpected analyzed model that are of interest to be explored. In particular, the uniaue differences of macromolecular aggregation state arrangement in liquid crystal state dependent on free cooling between hv-Lc- and Sc-SCLCPs were observed from POM.

■

ate),20−22 polybutadiene23−25 and polystyrene.26−28 Polymeric backbones could be divided into many categories according to the morphology of molecules, including morphological linear, star, brush, cyclic, dendrimer, dendritic and hyper-branched systems. These polymeric backbones with various functional points, such as vinyl,25,29 silyl-hydride (SiH),18 hydroxyl (OH),23 thiol (SH),30 or even N-containing groups31 that led to the formation of a hydrogen bond or an ionic bond, can be functionalized via various methods including “click” chemistry,24,30 hydrosilylation,19 acyl−chloride esterification,32−35 or self-assembly.13,27,31 So SCLCPs with fascinating morphological architectures can be obtained efficiently and conveniently. Since Pugh et al.36 reported the effect of molecular architecture with branched systems on the thermal behavior; branched LC polymers have attracted considerable attention. Despite of extensive research on SCLCPs, related works about the effect of topology on LC properties have been seldom

INTRODUCTION In the past several decades, side chain liquid crystalline polymers (SCLCPs) with an excellent combination of liquid crystalline (LC) and polymer characteristics have gained contentious attentions and become a multidisciplinary field of research owing to the widespread applications. Recently, more attentions were paid to the appearing of new applications,1−8 the design of new molecular architectures9−13 and the discovery of new mosophases.14,15 With the fast development of the research and applications, developing new LC polymers with well-defined structures and properties become a dramatic challenge but of vital importance. Molecular engineering of LC is an important issue for controlling the relationship of structure−property. When designing a new LC polymer with excellent properties, polymeric backbones with well-defined structures are first considered, because it has been found that the topology of main chains distinctly influenced properties of new materials.16,17 The designs of polymeric backbones for SCLCPs are diverse and mainly derivative from traditional backbones including polysiloxane,18,19 poly(methyl acryl© XXXX American Chemical Society

Received: January 16, 2015

A

DOI: 10.1021/acs.macromol.5b00101 Macromolecules XXXX, XXX, XXX−XXX

Article

Macromolecules

“reverse” hydrosilylation. We not only investigated effects of Lc-/Sc-topology on the LC properties and molecular microstructures including molecular layer order of adjacent backbone and layer domain spacing, but also focused on the unique difference of two analogous architectures containing welldefined density of mesomorphic moieties. We synthesized hvor lv-PB, which achieved well-defined density of mesogenic moieties into the polymer skeletons. With regard to the density of comb-like side chains attached to PBs, it was evaluated by 1H NMR spectra of functionalized polymers. In particular, the difference of supramolecular aggregation arrangement for hvLc-SCLCPs and hv-Sc-SCLCPs was observed via POM for the first time, and it was found that the relationship of structure− property was determined by macromolecular side chain packing of analogous hv-/lv-architectures. In combination of various interaction forces and the relationship of structure−property, a possible model of topological macromolecular side chains packing was constructed for further analysis.

reported.17,37−49 The effect of diverse topology on the physical and biological properties, such as the switching time of LC, drug-loading capacity/drug-release rate,48 solution property,50 birefringence induction38 and photoinduced anisotropy13 has been investigated. Meanwhile, a few researches focus on the influence of topology on thermal and mesophase behavior,37,49 polymer with branched topology in Rao’s work51 showed a higher glass transition temperature (Tg) compared with linear polymers, while Zhao et al.38 developed a SCLCP with cyclic topology that exhibited a lower Tg, in addition, many research results indicated that the diverse topology could lead to varied mesophases such as smectic A, smectic C, and columnar phases etc.52 by controlling the design of molecules. Although more attentions were paid to the determination of layer-like order by LC microstructures, only a few works studied the effect of topology on molecular microstructures.17,38,39 The effects of topology on LC properties and molecular microstructures, even its relationship have been rarely depicted. Ganicz’s research39 showed that dendritic polymer led to shorter ΔT and lower molecular order in comparison with linear analogues. However, in many cases, LC properties and molecular order are determined by many factors; in particular, the significant influence of various interaction force and the density of functionalized points have been confirmed by DeLongchamp et al.53 Their research results indicated that a low linear side chain attachment density led to formation of a highly ordered structure that permitted side chain interdigitation between adjacent backbone layers. Furthermore, branched polymers with fascinating architectures and low intrinsic viscosity have multiple potential applications and are proving particular versatile. So a further systematic research on branched SCLCPs is of high value. In the field of functional branched polymers, the synthesis of side chain functional groups is relatively convenient; one of key barriers is obtaining varieties of branched backbones. In many cases, it was found that the well-defined branched polymers with mesogenic moieties have gained important properties;48 however, their preparation was always a complicated and consuming multistep process. With regard to this field, our groups have successfully synthesized well-defined high 1,4- (low vinyl, lv) linear or 4-arm star polybutadienes (L-/S-PBs) by living anionic polymerization.54−57 PB, as a very flexible backbone with relatively low Tg, have been grafted-onto by mesomorphic moieties,58,59 most researches focused on the changes of LC functional groups, while the effects of Lc- and Sc-topology on LC properties and microstructures have not been studied. On the fundamental side, there are two well-defined analogous microstructural systems including high 1,2- (high vinyl, hv) or 1,4- (lv) in PB backbones, the side chain attachment density was closely related to formation of microstructures,53 which provide a unique opportunity to research the relationship of structure− property systematically based on different well-defined density of functionalized points. In addition, PB naturally contains functional groups, double bond, which can be grafted-onto by “reverse” hydrosilylation39 without any post modifications to overcome self-cross-linking reaction.60 In this work, incorporation of −Si(CH3)2OSi(CH3)2H terminated mesomorphic moiety into hv- or lv-PB with linear and star topology, and then in two analogous architectures including lv-/hv-counterparts, new series of different molecular weight Lc-SCLCPs and Sc-SCLCPs were respectively synthesized through combination of living anionic polymerization and

■

EXPERIMENTAL SECTION

Materials. Butadiene (Yanshan Petrochen. Co., China, polymerization grade) was treated with a small amount of n-butyllithium (nBuLi) to remove the moisture and inhibitor. n-BuLi (Initiator, JK Chemical, 2.5 M solution in n-hexane). Cyclohexane (Jinxi Chemical Plant, China, polymerization grade) was dried and stored over activated 5 Å molecular sieve and deoxygenated. 2-propanol (Terminating agent, Tianjin Bodi Chemial Co., Ltd., China, analytical reagent) was degassed via three freezing-evacuation-thawing cycles. Tetrachlorosilane (Coupling agent, SiCl4, JK Chemical, 1.45 g/mL) was dried over CaH2 and distilled. 1,2-Dipiperidinoethane (DPE, high vinyl polar additive, Acros Orcannics, 98%) dried over CaH2 and distilled under high vacuum conditions, was diluted with dry benzene to get 0.152 M solution in benzene. Toluene used in the hydrosilylation reaction was taken from an Innovative Technologies, Inc., solvent purification system. Cholesterol and 4-Hydroxybenzonic acid (Sinopharm Chemical Reagent Co., Ltd., China, analytical reagent), 1-Bromopropene and 1,1,3,3-Tertramethyldisiloxane (Alfa Aesar, 99%, 97%, respectively), no purification was performed on any of the reagents. Pt(0)-1,3-divinyl-1,1,3,3-tetramethyl disiloxane complex solution in xylene (Karstedt-type catalyst, Pt2̃ %, Sigma-Aldrich). All the other chemical reagents such as CHCl3, pyridine and SOCl2 (Tianjin Bodi Chemial Co., Ltd., China, analytical reagent) were purified in the conventional methods. Methods. Fourier transform infrared (FT-IR) spectra of all synthesized intermediates, monomers and polymers were acquired on Nicolet 6700 Flex spectrometer using KBr pellets. Proton nuclear magnetic resonance (1H NMR) spectra of all the products were obtained on an Advance (Bruker Co., Ltd., Germany) 400 MHz NMR spectrometer at ambient temperature with CDCl3 as solvent, 1H NMR was used to determine molecular structure, additionally to evaluate the addition efficiency of Si−H terminated mesomorphic moieties grafted onto PBs. The number-average molecular weight (Mn) and PDI of the polymers were determined using GPC and the instrument was a Viscotek TDA-305 GPC (Viscotek Corp., Houston, TX) equipped with tetra detectors [refractive index (RI), UV, viscosity(VISC), and two-angle laser light scattering (7° and 90°, laser wavelength, λ = 670 nm)] and two separation columns (Malvern, T6000 M×2), Ps sample (Viscotek Corp. Mw = 104.071 kg/mol, Mn = 100.967 kg/mol) was used to calibrate the instrument. The dn/dc value of this standard was 0.185 mL/g. THF was used as the mobile phase at a flow rate of 1.0 mL/min and the column temperature of 35 °C. The samples were dissolved in THF with the concentrations of less than 2.0 mg/mL, depending on the precise concentration injected to characterize the composition of SCLCPs precisely. The obtained data wes analyzed using OmniSEC software version 4.7.0 (Viscotek Corp.). Mesophasic textures and supramolecular aggregation arrangements were recorded by polarized optical microscopy (POM) using a Leica DMLP B


Article

Macromolecules equipped with a hot stage. Phase transitions were determined using a TA DSC Q520 instrument under a nitrogen atmosphere with powdered samples sealed in aluminum pans. Tg was determined at the midpoint of the baseline jump, and other phase transition different from Tg such as the isotropization temperature (Ti) was read at the maximum of corresponding peaks. Thermogravimetric analysis was performed using a TA Q500 instrument at a heating rate of 10 °C/min under a nitrogen atmosphere. Wide-angle X-ray diffraction (WAXD) were performed using a Bruker D8 Advance X-ray diffractometer with a Cu Kα radiation source (wavelength λ = 1.5 Å). The samples were heated by a programmable temperature controller at a range of mesophase temperature and the scattering angle theta was controlled 1° < 2θ < 30°. Small-angle X-ray scattering (SAXS) experiments were also performed; with a wavelength of λ = 1.54 Å and sample detector distance of D = 1074 mm, the resolution ration of the detector was 100 μm × 100 μm. Synthesis of LC Intermediate Cholesteryl-4-allyloxybenzoate: Chol-vinyl(IM). This reactive intermediate was synthesized according to the reported method.61 4-hydroxybenzoic acid (70 g, 0.5 mol) (1) were dissolved into 250 mL absolute ethyl alcohol in a round-bottom flask. Additionally, KOH (67 g, 1.2 mol) and KI (0.5 g, 3 mmol) dissolved in water were cooled down to room temperature, and the solution was added dropwise into the first solution, which was stirred for 2 h at room temperature. Then 1-bromopropene (60g, 0.5 mol) was added dropwise into aforementioned mixture. After it was stirred and heated to reflux for 16 h, the mixture was cooled and poured into aqueous solution of HCl, a white solid was obtained after it was filtered. The product 4-allyloxybenzoate (2) was recrystallized from hot alcohol in 90% yield. 2 (35.6 g, 0.2 mol) dissolved in thionyl chloride (42.7 mL, 0.6 mol) was stirred for 2 h at room temperature and then heated to reflux for 5 h, a yellow liquid (3) was obtained after the removal of redundant under reduced pressure in 98% yield. 3 (20 g, 0.1 mol) dissolved in CHCl3 (20 mL) was dropped slowly into cholesterol dissolved in a mixture of pyridine (20 mL) and CHCl3 (150 mL), which was heated to reflux for 6 h. After the removal of solvent, the residue was poured into aqueous solution of HCl (pH = 3−4) overnight and filtered by washing to neutral. The product was recrystallized from hot alcohol and purified by a silica gel column with 100:1 (v/v) hexane:ethyl acetate to obtain the important intermediate Chol-vinyl(IM) (4) in 80% yield. 1H NMR (CDCl3): δ (ppm) = 7.99 (2H, d, Ar−H), 6.92 (2H, d, Ar−H), 6.05 (1H, m, CH2CH− CH2−), 5.44 (1H, d, one of CH2CH−CH2−O−), 5.40 (1H, t, −CCH− in cholesteryl moiety), 5.31 (1H, d, one of CH2CH− CH2−), 4.83 (1H, m, −O−CH− in cholesteryl moiety), 4.68 (2H, d, CH2CH−CH2−O−), 2.45 (2H, d, −O−CH−CH2− in cholesteryl moiety), 0.86−2.01 (38H, m, H in cholesteryl moiety), 0.69 (3H, s, −CH3 in cholesteryl moiety). Synthesis of LC Monomer Cholesteryl-4-(3-(1,1,3,3tetramethyldisiloxany)propoxy)benzoate: Chol-SiH(M). This synthesis is similar to that reported previously.19 1,1,3,3-Tetramethyldisiloxane (100g, 0.73 mol) and toluene (100 mL) were mixed at room temperature. A second solution with 4 (20g, 36.6 mmol), toluene (150 mL), and a Karstedt-type catalyst (1 mL) complex solution in xylene was mixed. This solution was added dropwise to the first solution to obtain a yellow solution and then stirred overnight at 60 °C under N2. After the removal of solvent, the product (5) was separated with 1:100 (v/v) ethyl acetate:hexane on a silica gel column to obtain 14.9 g in 60% yield. 1H NMR (CDCl3): δ(ppm) = 7.99 (2H, d, Ar−H), 6.92 (2H, d, Ar−H), 5.40 (1H, t, −CCH− in cholesteryl moiety), 4.83 (1H, m, −O−CH− in cholesteryl moiety), 4.69 (1H, s, Si−H), 3.92 (2H, d, −CH2−CH2−CH2−O−), 2.45 (2H, d, −O− CH−CH2− in cholesteryl moiety), 1.8 (2H, m, Si−CH2−CH2−CH2− O−), 1.02 (2H, Si−CH2−CH2−), besides, 0.86−2.01 (38H, m, H in cholesteryl moiety), 0.69 (3H, s, −CH3 in cholesteryl moiety), 0−0.25 (12H, m, Si(CH3)2OSi−(CH3)2). The detailed synthetic route is shown in Scheme 1. Synthesis of a Series of Different Molecular Weight L-/4Arm S-PBs via Anionic Polymerization. All the anionic polymerizations were carried out under an inert atmosphere via standard Schlenk techniques and cannula transfer. The glass assembly was dried

Scheme 1. Complete Synthetic Route of SCLCPs That Presented the Changes of Different Functional Groups of Representative Products

with three cycles of a flaming/N2-purging/evacuating before polymerization initiated. Basic composition characterizations of PB backbones (GPC etc.) will be given in Table 1. Synthesis of lv-L/4-Arm S-PB. All synthesized different molecular weight backbones were added equally via a channel-pin from the same flask with butadiene in order to avoid the influences of impurities and variation of the structure. This is a typical anionic polymerization reaction,54−56 in which the living PBLi was synthesized by living anionic polymerization of butadiene (5.0 g, 92.6 mmol) with n-BuLi (according to the target designed Mn) in cyclohexane at 50 °C for 3h. By quenching the living PBLi with the degassed 2-propanol, the polymer was precipitated by pouring it into a large amount of methanol and vacuum-dried at 40 °C for more than 24h to obtain lv-L-PBs. Similarly, the resultant living PBLi was prepared via the method aforementioned was injected with coupling agent SiCl4 (in theory, [SiCl4]/[n-BuLi]) = 1/4, molar ratio, in general, excess of 10% living PBLi to obtain four-arms PB) via a syringe. It was kept at 50 °C for another 5 h and then, was quenched with degassed 2-propanol. lv-S-PBs obtained by fractionation were purified in 95% yield. The vinyl content calculated by 1H NMR spectra of all the obtained lv-L-/S-PBs was between 8% and 12%. Synthesis of hv-L/S-PB. This anionic polymerization reaction23,62 was similar to the method aforementioned of lv-PB, except that a polar C


Article

Macromolecules Table 1. Molecular Composition Characterization of lv-/hvTopological PB Backbones backbones

Mne

PDIf

1,2-, %g

1,4-, %h

lv-L-PB-2ka lv-L-PB-4k lv-L-PB-5k lv-L-PB-7k lv-L-PB-10k lv-L-PB-18k lv-S-PB-2kb lv-S-PB-4k lv-S-PB-5k lv-S-PB-6k lv-S-PB-7k lv-S-PB-10k lv-S-PB-18k hv-L-PB-4kc hv-L-PB-7k hv-L-PB-10k hv-L-PB-18k hv-S-PB-4kd hv-S-PB-7k hv-S-PB-10k hv-S-PB-13k

1.8 3.9 4.8 6.9 10.5 17.9 2.2 3.8 4.7 5.6 6.6 10.1 18.0 3.9 6.8 10.4 18.0 4.0 7.1 9.8 12.8

1.09 1.20 1.21 1.22 1.19 1.25 1.27 1.25 1.18 1.20 1.09 1.17 1.12 1.12 1.09 1.10 1.09 1.15 1.16 1.16 1.23

10.0 8.0 8.0 8.0 8.0 8.0 12.0 10.0 8.0 9.0 10.0 10.0 9.0 89.0 83.0 87.0 89.0 85.0 87.0 87.0 84.0

90.0 92.0 92.0 92.0 92.0 92.0 88.0 90.0 92.0 91.0 90.0 90.0 91.0 11.0 17.0 13.0 11.0 15.0 13.0 13.0 16.0

Scheme 2. Preparation Route of Lc/Sc-SCLCPs in Combination of Living Anionic Polymerization and “Reverse” Hydrosilylation

Si(CH3)2OSi(CH3)2H terminated LC moieties were incorporated into topological PB backbones to obtain Lc-/Sc-SCLCPs. Chol-SiH(M) was obtained by the method of preliminary modification for monomer that was based on hydrosilylation of Chol-SiH(IM) bearing terminal vinyl groups.39 In this method, Si−H moiety was from HSiMe2OSiMe2SiH, and there is no limitation for the structure of a mesogen, that in fact, the reaction required large excess of disiloxane in order to reduce double substituted side product (RSiMe2OSiMe2SiR) instead of the desired (RSiMe2OSiMe2H). PB based on dienes contains side-on functionalized points was used for further chemical reactions without any post modification, so that various LC monomers can be grafted on PBs. In this paper, lv(hv)-L(S)-PBs were typically synthesized by living anionic polymerization. Chol-SiH(M) was grafted onto PB backbones via “reverse” hydrosilylation. Side chain attachment approach of hydrosilylation was described by Verploegen.63 In general, the reaction occurred between the backbones containing Si−H and the side chain groups containing terminal vinyl, however, in this work, PBs containing double bonds reacted with side chains containing Si−H called “reverse” hydrosilylation, which lead to two important advantages for LC moieties incorporation, first, incomplete post modification such as from epoxidation to ring-opening reaction55,56 of PBs may generate post functionalized self-crosslinking;60 moreover, the purification process of macromolecules is relatively complicated, and micromolecules are easily modified and purified instead.19 This “reverse” hydrosilylation was compared with the most established way “thiol−ene chemistry” for anionic polymers with vinyl group,66,67 both of them have the advantages of easy operation, quick installation, while, in this work, “reverse” hydrosilylation was employed, first, −Si(CH3)2OSi(CH3)2− moiety was conveniently introduced, that in fact, this moiety significantly influenced molecular order and phase behavior;68 additionally, it was well-established that hv-PB submitted to thiol−ene reaction conditions, tend to form cyclic adducts, which usually limited the functionalization to less than 50%.62 In the typical hydrosilylation reaction, the excess of alkenyls or vinyl groups is necessary, in our work of “reverse” hydrosilylation, the use of excess of Si−H terminated mesogens aimed to achieve as high addition to double bond groups as possible. However, experimental results showed that it was impossible to obtain complete addition, incomplete addition was mainly due to increased steric hindrance, and the access will became increasingly difficult for higher generations, even

a

lv-L-PB-2k represented low vinyl (high 1,4-) content linear PB backbones with Mn = 2 kg/mol. blv-S-PB-2k represented low vinyl (high 1,4-) content 4-arm star PB backbones with Mn = 2 kg/mol. chvL-PB-2k represented high vinyl (high 1,2-) content linear PB backbones with Mn = 2 kg/mol. dhv-S-PB-2k represented high vinyl (high 1,2-) content 4-arm star PB backbones with Mn = 2 kg/mol. eMn (kg/mol) represents number-average molecular weight calculated precisely by GPC. fPolydispersity index determined by GPC. g1,2Content (%) calculated by 1H NMR, according to eq S2, Supporting Information. h1,4-Content (%) calculated by 1H NMR, according to eq S3, Supporting Information. additive DPE was injected before injecting n-BuLi ([DPE]:[n-BuLi] = 1:1, molar ratio) kept at 35 °C. The pure hv-S-PBs in 80% yield were determined by the comparison of GPC traces of the fractionated and crude polymers. The vinyl content calculated by 1H NMR spectra of all obtained hv-L/S-PB was between 83% and 89%. Synthesis of Lc/Sc-SCLCPs with Analogous lv-/hv-Architectures via “Reverse” Hydrosilylation. All the same series of hydrosilylation were carried out at the same time, and the reactions were all on the conditions of an Innovative Technologies, Inc., glovebox in order to overcome the interference of external conditions (shown in Scheme 2.). To different flamed Schlenk tubes with different molecular weight PBs (100 mg, 1.85 mmol double bonds), Chol-SiH(M) dissolved in 20 mL of dry toluene (1.54 g, 2.22 mmol SiH groups) was added respectively (double bond:SiH = 1:1.2, input molar ratio), and then Karstedt’s catalyst (10 drops) was added into this system, respectively. The reaction mixture was stirred at 30 °C for 72 h under argon. Solvent was removed by rotary evaporator under reduced pressure, and polymer was purified by twice cooled precipitations from hot cyclohexane/ethyl alcohol mixtures, then frozen precipitation in the mixtures of diethyl ether and a small amount of ethyl alcohol, and finally drying under vacuum.

■

RESULTS AND DISCUSSION Synthesis and Structure Characterization of Monomer and Polymers. The effective strategy for the preparation of SCLCPs in combination of living anionic polymerization and “reverse” hydrosilylation is shown in Scheme 2. In this strategy, the set of polymers with same side chains gave a unique opportunity to study LC property-structure relationship. D


Article

Macromolecules

Figure 1. FT-IR progress spectra of the synthetic process including representative intermediates and LC monomer Chol-SiH(M).

Figure 2. Representative FT-IR spectra, compared Chol-SiH(M), lv-/hv-PB with lv-/hv-SCLCPs (a′ and b′), separately corresponding to partial enlargement FT-IR spectra (a and b).

FT-IR Characterization. A complete synthetic route of CholSiH(M) and SCLCPs is shown in Scheme 1. The progress of the four steps synthetic process in Chol-SiH(M) was detected

increasing the concentration of Si−H group (double bond:SiH = 1:3 molar ratio), and elevating temperature (T) from 30 to 60 °C. E


Article

Macromolecules

HSiMe2OSiMe2H to obtain Chol-SiH(M). It was supported by the disappearance of the peaks δ = 6.05(1H), δ = 5.44(1H), and δ = 5.40(1H) assigned to the terminal vinyl in the spectra of Chol-vinyl(IM) and the appearance of a new peak at δ = 4.66 assigned to terminal Si−H in spectra of Chol-SiH(M). More importantly, with the disappearance of terminal vinyl, the chemical shift of the characteristic peak δ = 4.68 assigned to methylene adjacent to terminal vinyl and oxygen moved to δ = 3.92 assigned to methylene adjacent to oxygen, the characteristic peak δ = 3.92 was typical existing in Chol-SiH(M) while inexistence in PBs. On the basis of this fact, the addition efficiency of Chol-SiH(M) grafted onto PBs could be evaluated by the 1H NMR of obtained SCLCPs. Representative 1H NMR spectra of lv-/hv-SCLCPs were compared with that of Chol-SiH(M) and lv-/hv-PBs, shown in Figure 4. All the 1H NMR spectra including PB backbones and SCLCPs were shown in Supporting Information. It was found that the characteristic peak δ = 5.40 assigned to alkenyl group in cholesterol mixed together with the peak δ = 5.50 of 1,4olefin and a part (-CH=CH2) of 1,2- olefin from PBs. Similarly δ = 4.83 assigned to methyne in cholesterol adjacent to oxygen mixed together with δ = 4.90 assigned to 1,2-olefin (−CH CH2) of PBs. In addition, the disappearance of characteristic peak δ = 4.69 assigned to Si−H groups indicated that SCLCPs were purified without Chol-SiH(M). So the addition efficiency (EA) (the percentage of reactive double bonds in total double bonds of backbones) of SCLCPs was calculated by 1H NMR. And the calculation results of SCLCPs were summarized shown in Table 2. Similarly, the percentage content of 1,4-olefin and 1,2-olefin of PBs were also calculated by 1H NMR (shown in Table 1.). The detailed calculation methods were seen in Supporting Information. The Prediction of Individual Macromolecular Side Chain Packing via 1H NMR Calculation. The double bonds of PBs exist in each 1,4- or 1,2-monomeric unit for further reactions. lv-PBs possesses low Tg, expected to achieve SCLCPs with low Tg. Additionally, suspended 1,2-olefins were advantageous for addition.69 Thus, hv-PBs was synthesized, expected to achieve high EA(total), which was beneficial to generate various mesophases in a quite wide mesomorphic temperature range. To explain this, the “reverse” hydrosilylation reactions at 30 °C were desired (double bond:SiH = 1:1.2, input molar ratio). Experimental results showed that suspended 1,2-olefins indeed

by FT-IR, shown in Figure 1. which presented the changes of different functional groups from 1 to 5 in Scheme 1. In CholSiH(M), the absorption peak at 1651 cm−1 disappeared, and the peak at 1672 cm−1 remained; meanwhile, the absorption peak at 2166 cm−1 of Si−H group appeared, demonstrating that double bonds in cholesterol groups did not participate in the addition reaction, as terminal vinyl were used instead, and the product Chol-SiH(M) was obtained. The final product SCLCPs were synthesized by “reverse” hydrosilylation of Chol-SiH(M) and lv/hv-L/S-PB. In the synthetic route, representative FT-IR spectra, comparing Chol-SiH(M) and lv-/hv-PB with lv-/hv-SCLCPs, are shown in Figure 2. In SCLCPs, the absorption peak at 1713 cm−1 was exhibited, and the absorption peak at 1658 cm−1 remained; meanwhile, the absorption peak at 1642 cm−1 and the absorption peak at 2166 cm−1 of the Si−H group disappeared, demonstrating that pure SCLCPs were obtained, and incomplete addition reaction could be observed. The detailed absorption assignment was described in the Supporting Information. 1 H NMR Characterization. The structure comparison of Chol-vinyl(IM) and Chol-SiH(M) were detected by 1H NMR, shown in Figure 3. Chol-vinyl(IM) was used to react with

Figure 3. Structure comparation of Chol-vinyl(IM) and Chol-SiH(M) detected by 1H NMR.

Figure 4. Representative 1H NMR spectra of lv-/hv-SCLCPs, compared with Chol-SiH(M) and lv-/hv-PB. (a) 1H NMR comparison of lv-SCLCPs, Chol-SiH(M) and lv-/hv-PB; (b) hv-SCLCPs, Chol-SiH(M) and lv-/hv-PB. F


Article

Macromolecules Table 2. Addition Efficiency and Molecular Composition Characterization of lv-/hv-SCLCPs lv-/hv-SCLCPs

Mn (kg/mol)c

PDId

1,2-EA (%)e

1,4-EA (%)f

EA(total) (%)f

lv-L-PB-2k-LCP lv-L-PB-2k-LCPT lv-L-PB-4k-LCPa lv-L-PB-5k-LCP lv-L-PB-7k-LCP lv-L-PB-10k-LCP lv-L-PB-18k-LCP lv-S-PB-2k-LCP lv-S-PB-4k-LCPb lv-S-PB-5k-LCP lv-S-PB-6k-LCP lv-S-PB-7k-LCP lv-S-PB-7k-LCPT lv-S-PB-10k-LCP lv-S-PB-18k-LCP hv-L-PB-4k-LCPa hv-L-PB-7k-LCP hv-L-PB-10k-LCP hv-L-PB-18k-LCP hv-L-PB-4k-LCPT hv-L-PB-7k-LCPT hv-S-PB-4k-LCPb hv-S-PB-7k-LCP hv-S-PB-10k-LCP hv-S-PB-13k-LCP hv-S-PB-4k-LCPT hv-S-PB-7k-LCPT

10.0 10.8 23.2 27.2 40.3 59.2 80.0 10.9 17.5 23.4 25.4 33.9 33.2 54.0 85.9 32.2 56.7 87.2 142.0 40.7 72.0 36.7 65.7 90.0 108.0 36.9 66.8

1.15 1.17 1.23 1.08 1.17 1.23 1.07 1.29 1.23 1.22 1.19 1.11 1.13 1.16 1.17 1.23 1.07 1.12 1.11 1.20 1.09 1.16 1.25 1.24 1.23 1.17 1.23

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 68.1 71.7 67.1 61.2 86.7 88.7 77.6 77.5 76.4 69.9 80.0 78.5

33.1 36.7 36.1 31.4 33.2 31.7 21.2 25.9 23.9 28.3 23.4 28.0 23.1 27.0 23.7 3.6 8.8 7.7 4.5 10.8 8.2 8.7 1.5 0.8 5.6 2.7 4.6

39.8 43.0 41.2 36.9 38.5 37.2 27.5 34.8 31.5 34.0 30.3 35.2 30.8 34.2 30.6 61.0 60.5 58.5 55.0 76.8 75.0 67.6 67.6 66.6 59.6 68.4 68.9

a

lv-(hv-)L-PB-4k-LCP represented lv-/hv-SCLCPs with Mn = 4 kg/mol L-PB backbones. blv-(hv-)S-PB-4k-LCP represented lv-/hv-SCLCPs with Mn = 4 kg/mol S-PB backbones. cMn represented number-average molecular weight calculated precisely by GPC. dPolydispersity index determined by GPC. eNoted the percentage of reactive double bonds in total double bonds of backbones calculated by 1H NMR, according to eq S6. fNoted the percentage of reactive double bonds in total double bonds of backbones calculated by 1H NMR, according to eq S7. fNoted the percentage of reactive double bonds in total double bonds of backbones calculated by 1H NMR, according to eq S5. TRepresent SCLCPs obtained on different reaction conditions: reaction temperature: 60 °C, double bond:SiH = 1:3, input molar ratio, reaction time: 72h.

achieved higher EA(total) (30−40%) than 1,4-olefins (60− 70%). On the one hand, EA(total) of hv-SCLCPs was higher than that of lv-SCLCPs. On the other hand, a small amount of 1,2-olefins for lv-SCLCPs reacted completely, while the same small amount of 1,4-olefins for hv-SCLCPs reacted incompletely. 1,4-olefins of PBs were constrained by steric hindrance from main chains and side chains, while suspended 1,2-olefin of PBs was flexible to overcome influence of main chains. But, it was found that all the reactions were incompletely. In order to achieve as high addition to PBs as possible, elevating reaction T to 60 °C was tried, at the same time, larger excess of CholSiH(M) was used from 20% excess to 200% excess of Si−H groups (from double bond:SiH = 1:1.2, to double bond:SiH = 1:3, molar ratio). However, the results showed that EA remained unchanged except for that of hv-Lc-SCLCPs (75%) increasing by 15%, which indicted that, with elevating reaction T, suspended 1,2-olefins with much higher kinetic constant with respect to 1,4-units were more easily activated to react. For lv-SCLCPs, the EA did not increase distinctly, because 1,2addition has been complete at 30 °C, elevating reaction temperature to 60 °C did not show a higher EA. For hvSCLCPs, 1,2-addition was incomplete at 30 °C, when elevating T to 60 °C, more 1,2-olefins were activated, hence the EA of hvLc-SCLCPs increased by 15%, while for hv-Sc-SCLCPs, Scsystems could be regard as a sphere-like in solution similar to our research56 and literature,39 when closed to the center of

sphere, steric hindrance of branched systems was raised, so more vinyl were remnant, that made side chains from different branched arms interpenetrative, while when closed to surface of the sphere, steric hindrance of branched systems was relatively decreased, most vinyl groups reacted, although elevating T to 60 °C, the rest vinyl constrained in the center of the sphere was difficult to react due to increased steric hindrance, the EA of hvSc-SCLCPs remained unchanged. At this moment, no matter hv-Lc-SCLCPs or hv-Sc-SCLCPs, it was still impossible to obtain complete addition, and the incomplete addition was mainly due to increased steric hindrance of branched systems. In the following discussion, reaction condition of obtained SCLCPs was no detailed illustration, except for hv-Lc-SCLCPs obtained at 60 °C. With regard to SCLCPs, we support that small differences of EA from incomplete hydrosilylation did not affect liquid crystalline properties significantly,39 because the small EA difference resulted from adjacent side chains, while it was the key that the deep interpenetration from different macromolecules to determine properties and molecular layer order. According to experimental results, we believe, the differences less than 10% did not affect liquid crystalline properties and corresponding microstructures significantly. GPC Characterization. L-/S-PBs were obtained via living anionic polymerization. Hence, symmetric and narrow single peak were all observed in the GPC traces of the resultant L-PB, which are shown in Figure 5(1). In addition, the phenomenon G


Article

Macromolecules

Figure 5. GPC elution curves of (1), PB main chains with various topologies and (2), SCLCPs with various topologies. (1) (a) GPC traces of lv-LPBs; (b) GPC traces of lv-S-PBs; (c) GPC traces of hv-L-PBs; (d) GPC traces of hv-S-PBs. (2) (a) GPC traces of lv-L-SCLCPs; (b) GPC traces of lv-S-SCLCPs; (c) GPC traces of hv-L-SCLCPs; (d) GPC traces of hv-S-SCLCPs.

to the one arm PB and 4-arm S-PB overlap slightly in the chromatogram of the mixture, and the ratio of the 4-arm S-PB to unlinked one arm PB prior to fractionation was

of typical double peaks was observed in GPC traces of crude SPB, especially for hv-S-PB in 80% yield. The representative GPC curve was shown in Figure S7. The peaks corresponding H


Article

Macromolecules

Figure 6. WAXD patterns on cooling of SCLCPs with different molecular weight. (respectively exhibiting Bragg diffraction angle and relative Bragg diffraction intensity within 2θ < 5°, such as 2.29 and 106): (a) lv-Lc-SCLCPs on cooling 80 °C; (b) lv-Sc-SCLCPs on cooling 80 °C; (c) hv-LcSCLCPs on cooling 100 °C; (d) hv-Sc-SCLCPs on cooling 100 °C.

approximately 4:1 based on GPC RI peak areas. 4-Arm S-PB and unlinked linear arm PB purified from precipitation fractionation respectively, taking on narrow signal peak in GPC curves (shown in Figure 5 (1).) the molecular weights of both the polymers were determined by GPC. The basic characterization of PBs was displayed in Table 1. All obtained PBs were grafted by LC moieties to obtain SCLCPs, detected by GPC. Excess of Chol-SiH(M) were removed from the crude products to obtain pure SCLCPs, GPC traces were described in Figure 5 (2). The basic characterizations of SCLCPs were summarized in Table 2. X-ray Analysis. In order to identify the type of mesomorphic phase, X-ray measurement was essential to analyze various mesophases. Especially for the polymers, texture analysis of polymers from POM was far from being enough. In fact, details concerning molecular microstructures of SCLCPs could be

investigated by WAXD studies. First, WAXD can be used to indicate a layer-like correlation and then the correlation period was detected, for thermotropic SCLCPs, the correlation period was approximately equivalent to the domain spacing (dspacing) of a layer (d). Second, the Bragg intensity at small angles (in general, 2θ < 5°) was approximately related to molecular layer order; in other words, we speculated that adjacent molecular layer could be “locked” by interaction force, namely “interlocking-structure”, so the relative values of Bragg intensity were related to side chains interdigitation of adjacent layers, thereby revealing macromolecular side chain packing. In fact, as we all know, Bragg intensity at broad angles revealed molecular order of adjacent side chains, while for highly order layer-like structure, Bragg intensity at broad angles was relatively weak and the distribution was very broad. A large error could not adequately reveal the microstructure, so a sharp I


Article

Macromolecules

Figure 7. Tendency traces of d-spacing values and Bragg intensity dependent on molecular weight of SCLCPs: (a) lv-SCLCPs; (b) hv-SCLCPs.

SCLCPs exhibited similar patterns, one sharp peak at small angle regions, and the sharp peak position did not vary with the various temperatures. Several representative temperature dependent powder WAXD patterns in mesophasic temperatures were provided in Figures S10−S12. In addition, every peak was detected at corresponding d-spacing values of slightly more than d = 32 Å in small regions due to backbones dispersing side chains. It was demonstrated that obtained SCLCPs were smectic A. So the mesomorphic phase type did not vary with various topologies. However, data results demonstrated that for lv-SCLCPs and hv-SCLCPs, molecular microstructures changed with various topologies, and the tendency of d-spacing values dependent on different Mn was just contrary to that of Bragg intensity, indicating molecular microstructures was controlled by various topologies. According to the data results (Tables S1 and S2), the tendency of d-spacing values and Bragg intensity dependent on Mn of lv-SCLCPs and hv-SCLCPs was depicted in Figure 7. For lv-SCLCPs (Figure 7a), d-spacing values of Lc-SCLCPs were slightly smaller than that of the Sc counterpart; meanwhile, Bragg intensities of Lc-SCLCPs were distinctly stronger than those of the Sc counterpart except that when Mn = 18 kg/mol backbone, the flexibility of the backbone played an decisive role, and the Bragg intensity of Lc-SCLCPs distinctly decreased, while that of Sc-SCLCPs slightly decreased, resulting from a relatively shorter arm length. For lv-Sc-SCLCPs, Bragg intensity varied slightly along with different Mn, while for lv-LcSCLCPs, Bragg intensity increased distinctly along with increased Mn. The results indicated that Sc-topology of polymers led to lower layer order in comparison with Lc analogues due to weaker side chains “interlocking structure” of adjacent layers, thereby revealing lower molecular order. A similar result was reported that the dendritic type topology of polymers leads to lower molecular order in comparison with Lc analogues.39 In our group, similarly, it has been found that the fluorescence properties of polymer with Lc architecture were always better than those of the Sc counterpart due to its looser architecture.55,56 It was noteworthy that the conclusion aforementioned was completely contrary to analogous architectures of hv-SCLCPs (Figure 7b). In comparison relative Bragg intensity values of hv-Lc-SCLCPs and Sc counterparts, indicating that the Sc topology of polymers generated a stronger “interlocking structure” and led to a higher molecular order, which provided a new analytic model. For hv-SCLCPs, d-spacing values of ScSCLCPs were slightly smaller than those of the Lc-counterpart; meanwhile, the Bragg intensities of Sc-SCLCPs were distinctly

Bragg diffraction peak at small angles was employed to speculate on microstructures, and the “interlocking-structure” was a “positive effect” for molecular order. Powder WAXD Analysis of Liquid Crystalline Monomer. Powder WAXD patterns at the temperature within the range of mesomorphic formation, compared Chol-SiH(M) with Cholvinyl(IM), were shown in Figure S9. Chol-SiH(M) presented a sharp peak at small angles, suggesting existence of a layer-like correlation,64 while there was no sharp peak at small angle regions; meanwhile, a broad peak was observed at wide angle regions instead for Chol-vinyl(IM), which indicated a cholesteric phase combining with POM.61 In addition, we simulated the molecular model of Chol-SiH(M) via ChemBio3D; the theoretical coplanar molecular length (L) after energy minimization was 15.8 Å (seen in Figure S8). According to aforementioned, a single peak was observed in small angle regions (2θ = 2.75°) at corresponding d-spacing values of d = 32 Å, which was as two times long as the molecular length (L), namely d ≈ 2L, that suggested a double-molecular layer-like arrangement64 and a smectic A phase. Hence, the −SiMe2OMe2Si− unit introduced disrupted the molecular order to generate a new arrangement order. X-ray Analyses of SCLCPs: Construction of Topological Macromolecular Side Chains Packing Model of SCLCPs in lv-/hv-Architectures. As we all know, when LC monomers were grafted onto different backbones, molecular arrangement will be disrupted due to the structures of various backbones. According to aforementioned, Bragg d-spacing could indicate a layer-like correlation, and the relative Bragg intensity at small angles could approximately reveal macromolecular side chain packing resulting from molecular layer “interlocking-structure”. Hence, in order to research the relationship between topology and supramolecule microstructures, obtained SCLCPs were treated by annealing and then sufficient quantity of samples were tested to reduce the influence of background content. At this moment, Bragg intensity at small angles was only relevant to molecular layer order. In this work, WAXD of SCLCPs were tested on cooling within range of mesophasic temperature, relative intensity of lvSCLCPs kept consistent under 80 °C, similarly that of hvSCLCPs under 100 °C, so that 80 and 100 °C were chosen as desired testing and comparison condition, WAXD patterns of SCLCPs are shown in Figure 6. And the WAXD patterns of lvSCLCPs obtained on the reaction T 60 °C were shown in Figure S13. WAXD data analyses including d-spacing and the Bragg intensity of lv-SCLCPs and hv-SCLCPs were respectively summarized in Tables S1 and S2. First, all the obtained J


Article

Macromolecules Table 3. Representative Phase Behavior and Micro-Structures Data Comparison of lv-/hv-SCLCPs thermal behavior SCLCPs a

lv-L-PB-4k-LCP hv-L-PB-4k-LCPb lv-L-PB-7k-LCP hv-L-PB-7k-LCP lv-L-PB-10k-LCP hv-L-PB-10k-LCP lv-S-PB-4k-LCP hv-S-PB-4k-LCP lv-S-PB-7k-LCP hv-S-PB-7k-LCP lv-S-PB-10k-LCP hv-S-PB-10k-LCP

molecular microstructures

Tg (°C)c

ΔT (°C)d

d-spacing (Å)e

int. (au)f

q (nm−1)h

d′-spacing (Å)i

mesophaseg

25 41 32 40 32 40 13 38 21 40 20 41

111 164 118 169 118 172 85 172 99 180 101 185

37.9 36.8 37.7 35.2 37.7 34.5 41.6 34.1 40.1 32.7 38.2 32.7

193 165 945 205 990 215 55 227 159 1017 203 1259

− 1.51 1.46 −j − − 1.33 1.58 1.40 − − −

− 41.6 43.0 − − − 47.2 39.7 44.9 − − −

SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.) SmA(lamel.)

a lv-L-PB-4k-LCP represented linear-comb SCLCPs with low vinyl 4 kg/mol Mn backbones. bhv-L-PB-4k-LCP represented linear-comb SCLCPs with high vinyl 4 kg/mol Mn backbones. cGlass transition temperature on the second cycle heating. dΔT = Ti − Tg. eBragg domain spacing values, corresponding to the maximum of sharp diffraction peak at small angles, calculated according to the Bragg equation, 2d sin θ = nλ, n = 1, representing the first diffraction received from SAXS. fRelative Bragg intensity values (maximum value − minimum value), corresponding to sharp diffraction peak intensity at small angles. gMesophases and lamellar order structure were determined by polarized microscope observation and temperature-dependence powder WAXD. hq values, received from SAXS, calculated by empirical equation d′ = 2π/q. id′-spacing representing the correlation period, corresponding to the molecular layer distance, calculated by the empirical equation d′ = 2π/q. jKey: (−) no characterization. Conditions: obtained WAXD and SAXS data of lv-SCLCPs at 80 °C on cooling, obtained WAXD and SAXS data of hv-SCLCPs at 100 °C on cooling.

Figure 8. Several representative SAXS traces (a) at 80 °C of lv-SCLCPs and SAXS traces (b) at 100 °C of hv-SCLCPs.

stronger than those of Lc-SCLCPs. For hv-Lc-SCLCPs, the Bragg intensity varied slightly along with different Mn, while for hv-Sc-SCLCPs, the Bragg intensity increased dramatically along with increased star arm length. When elevating reaction T to 60 °C, only the Bragg intensity of hv-Lc-SCLCPs increased slightly, and the d-spacing values decreased slightly. In addition, with regard to SCLCPs, whether Lc-SCLCPs or Sc-SCLCPs, compared lv-SCLCPs and hv-SCLCPs with welldefined side attachment density (seen in Table 3 or Tables S1 and S2), the d-spacing values of hv-SCLCPs were slightly smaller than that of lv analogues. The results demonstrated that when the EA(total) was significantly raised, d-spacing values of SCLCPs become smaller, because the flexibility of backbones surrounded by side chains was constrained compactly by side chains. Unexpectedly, the Bragg intensity of hv-Sc-SCLCPs was significantly stronger than that of lv-Lc-SCLCPs, and the Bragg intensity of lv-Lc-SCLCPs was significantly stronger than that of hv-Lc-SCLCPs. It was demonstrated when the EA(total) was raised, hv-Lc-SCLCPs generated a weaker “interlocking effect” and led to lower layer and side chains order than lv-Lc-

SCLCPs; similarly, hv-Sc-SCLCPs generated the strongest “interlocking structure” and exhibited the strongest layer order and side chains order. However, macroscopically oriented samples may be not very accurate in small angle regions due to the limitation of the WAXD instrument. In order to confirm our view, the mesophase structures were characterized more precisely by SAXS instrument. Several representative SAXS traces of lvSCLCPs and were hv-SCLCPs are shown in Figure 8. Corresponding 2D SAXS spectra were shown in Figures S14−S17. The results were summarized in Table 3 (Table S3). The data confirmed our view that molecular microstructures were controlled by various topologies, moreover, for lvSCLCPs and hv-SCLCPs, a completely contrary conclusion about molecular microstructures resulting from topological structures was drawn. Accounting for this phenomenon from WAXD and SAXS results, combining with different EA(total) from 1H NMR, we speculated that the molecular layer and side chains order was related to Bragg intensity, and mainly controlled by interaction K


Article

Macromolecules

different molecules were difficult to interpenetrate due to steric hindrance. So the interpenetration force from different molecules was relatively weak, and hv-Lc-SCLCPs were like a comb-shape without any interpenetration force, generating weak Bragg intensity and “interlocking structure”, hence leading to a low layer order. The Bragg intensity of hv-Lc-SCLCPs slightly increased along with increased Mn due to increased interaction force of adjacent side chains, while the side chains “interlocking effect” of adjacent layers was not distinctly elevated. In combination with the calculation from 1H NMR, when elevating reaction T to 60 °C, EA(total) was raised, which was intended to increase interaction force of adjacent side chains. Therefore, the Bragg intensity slightly increased and dspacing values slightly decreased. For hv-Sc-SCLCPs, like a sphere, side chains from different branched arms close to the center of the sphere interpenetrated. Meanwhile the rest of the side chains close to the surface of the sphere dispersed out from the sphere, which was supported by the aforementioned evidence from 1H NMR. So for hv-Sc-SCLCPs, not only side chains from different branched arms inside the sphere interpenetrated, namely generating internal order, but also side chains out of the sphere from different molecules had the opportunity to interpenetrate, so generating the strongest Bragg intensity and “interlocking effect”. Hence, this led to higher side chain order and layer order, while at the same time smaller dspacing was observed. The superficial area of sphere increased along with increasing Mn. The stronger interpenetration force generated stronger Bragg intensity, hence giving higher side chains and layer order with smaller d-spacing. Even when the backbones Mn = 18 kg/mol, d-spacing values were two times as long as the molecular length (L), which suggested a doublemolecular layer-like arrangement, similar to LC monomer Chol-SiH(M). The Bragg intensity and “interlocking effect” were stronger than for Chol-SiH(M) due to macromolecular chains interdigitation. For SCLCPs (Table 3), according to the phenomenon and discussion aforementioned, d-spacings of hv-Lc-SCLCPs were smaller than those of lv-Lc-SCLCPs, while the Bragg intensity of lv-Lc-SCLCPs was stronger. d-Spacings of lv-Lc-SCLCPs (or hv-Sc-SCLCPs) were smaller than that of lv-Sc-SCLCPs (or hvLc-SCLCPs); meanwhile, the Bragg intensity of lv-Lc-SCLCPs (or hv-Sc-SCLCPs) was stronger than that of lv-Sc-SCLCPs (or hv-Lc-SCLCPs), which confirmed that d-spacing was controlled by cooperative interplay including interaction force of adjacent side chains from same molecules and interpenetration force from various molecules or different branched arms. However, the Bragg intensity, namely layer order or side chains “interlocking effect”, was mainly controlled by the interpenetration force from various molecules or branched arms. In most cases, properties were influenced by structures, so that we believe that the macromolecular side chains pacing resulting from cooperative interplay including interaction force of adjacent side chains and interpenetration force from different molecules or branched arms will influence thermal properties. Further research will be discussed in the thermal properties analysis. Properties Characterization. Mesomorphic Properties. Chol-vinyl(IM) in this work is a kind of very excellent LC reported in the literature.60 It has a wide ΔT and presents a cholesteric phase, with the typical oily streak, and focal conic textures were verified by POM on heating and cooling cycles (Figure S18). Chol-SiH(M) was derived from the hydrosilylation of Chol-vinyl(IM). The helix structure of the

force from side chains, especially deep interpenetration force from various macromolecules or branched arms, while the dspacing values were controlled by cooperative interaction force from adjacent side chains and interpenetration force from side chains of various macromolecules or branched arms, so according to side chains “interlocking structure” of adjacent layers via sharp Bragg diffraction peak intensity at small angles, in combination of the speculation of individual macromolecular side chains via 1H NMR calculation, we constructed topological macromolecular side chain packing models of lv-SCLCPs and hv-SCLCPs dependent on Mn (Figure 9).

Figure 9. Topological macromolecular side chain packing models and corresponding interaction force of adjacent or different side chains of lv-SCLCPs and hv-SCLCPs.

For lv-SCLCPs (Table S1), 1,4-olefins constrained by backbones were difficult to react, so EA(total) of lv-SCLCPs (Table 2) was relatively low. The backbones were surrounded by loosely side chains, lv-Lc-SCLCPs were like a comb shape, and the loose side chains from different macromolecular could interpenetrate each other, so increased interpenetration force led to a high molecular order, and interpenetration force increased dependent on Mn. When the Mn of backbones was large enough, the flexibility of PB backbones played an decisive role. The order of loose side chains was disturbed, thereby the side chain’s “interlocking structure” was disturbed in adjacent layers, and Bragg intensity significantly decreased. While lv-ScSCLCPs were sphere-like, in order to overcome steric hindrance, the loose side chains dispersed in different branched arms; meanwhile, the side chains were constrained by branched arms of main chains, so side chains from different branched arms of the same molecules had few probabilities to meet with each other, let along that from different molecules, so the interaction force of side chains was weak, which led to a lower molecular order. For hv-SCLCPs (Table S2), suspended vinyl groups were flexible to react, so EA(total) was distinctly higher than lvSCLCPs (Table 2), but it was impossible to obtain complete addition evaluated from 1H NMR. For hv-Lc-SCLCPs, backbones were surrounded compactly by side chains, so the interaction force of adjacent side chains from individual molecules was relatively strong, but the side chains from L


Article

Macromolecules

S22 (a). In the same way, Chol-SiH(M) was thermotropic LC. The DSC curve showed a Tm at 57 °C (corresponding enthalpy changes ΔHm = 19.01 J/g), and a smectic−isotropic phase transition (Tsi) at 146 °C (ΔHsi = 19.01 J/g) on second heating (ΔT = 89 °C), and displayed an Tis at 142 °C and a Tc at 19 °C on cooling, as shown in Figure S22 (b). Compared with Cholvinyl(IM), Chol-SiH(M) had a lower melting temperature and a shorter ΔT due to the flexible −SiMe2OSiMe2− introduced. Tg and Ti of SCLCPs are important parameters which have a large influence on the properties of polymers. In general, polymer backbone, length of flexible spacer and mesogenic core, terminal group, and the interaction force between side chains and rigid moieties could affect thermal properties.65 Introduction of rigid mesogenic groups into polymer backbone usually leads to an intermediate state of aggregation between crystalline and amorphous structures. With regard to LC polymers, a low Tg is necessary for application. And the flexibility of polymer backbone is an important factor in determining Tg, in addition, taken into consideration that the aforementioned −Si−O−Si− units introduced were favorable to generate low Tg. And the introduction of −SiMe2OSiMe2− will enhance the free volume of side chains and effectively disrupt chain packing and enhance segmental motion and tend to decrease Tg. PB is a highly flexible backbone; lv-PB prepared via anionic polymerization has a low Tg approaching −90 °C in its nonfunctionalized formation. It was chosen to enable a low Tg even after functionalized formation. DSC curves dependent on Mn of lv-SCLCPs on the second heating cycle are shown in Figure 12(1). (corresponding cooling DSC curves are seen in Figure S23). The corresponding phase transition temperatures were summarized in Table S4. According to results, a ΔT comparison of lv-Lc-SCLCPs and Sc counterparts was displayed in Figure 13a. When SCLCPs were heated, DSC curves all showed two endothermic peaks corresponding to Tg and Ti, respectively. For lv-Lc-SCLCPs with different Mn values, both Tg and Ti first elevated then lowered along with the increasing Mn of backbones, so that ΔT changed indistinctly except for the polymer with Mn = 18 kg/mol backbone, which decreased distinctly. For lv-Sc-SCLCPs with different Mn of backbones, Tg, Ti, and ΔT take on the tendency of gradually increasing, except for the Mn = 18 kg/mol backbone decreasing slightly. To explain this phenomenon, the macromolecular side chains packing model (Figure 9.) from X-ray and 1H NMR was utilized. Both Tg and Ti were influenced by many related factors as aforementioned, in this work. Many factors were approximately consistent except for polymer backbones and the interaction force of side chains. The decoupling of mesogens and PB backbones, thus acting independently, backbone was surrounded by loose side chains for lv-SCLCPs. Considering two factors included aforementioned, for lv-LcSCLCPs, loose side chains were interpenetrative each other, side chains interpenetration force from different molecules may withhold the free movement of backbones, interpenetration force played a decisive role intending to increase Tg and Ti along with increasing Mn, when the flexibility of backbone played a decisive role, intending to deduce the Tg. For lv-ScSCLCPs, like a sphere-shape, when star arm length was short, loose side chains dispersed on different arms from same molecules, along with increasing arm length, side chains from various macromolecules penetrated into inner sphere tending to elevate Tg and Ti. In particular, lv-Sc-SCLCPs presented room temperature Tg which was desired for application, for

cholesteric phase was restrained, while distinct lamellar structure was observed instead, due to the flexible −Si−O− Si− introduced, which led to a smectic A. POM results showed that Chol-SiH(M) exhibited a typical fan-shaped texture of SmA when heated and cooled. And the optical images of CholSiH(M) were displayed in Figure 10. And all the colors observed were not due to selective reflection.

Figure 10. POM-50 μm images of liquid crystalline monomer CholSiH(M) at different temperatures on heating and cooling (a) fanshaped texture, 107 °C on heating, (b) 120 °C on heating, (c) 114 °C on cooling, and (d) focal conic texture, 92 °C on cooling.

With regard to SCLCPs, several typical optical images were displayed and all the SCLCPs exhibited LC phases. As can be seen in Figures S19 and S20, lv-SCLCPs exhibited similar textures, when the temperature was low. The textures were not obvious, while when adding pressure on the polarized film, it moved. Until drawing near to the isotropic state, the texture more or less appeared, and fan-shaped textures were formed gradually. With regard to hv-SCLCPs, the pretty fan-shaped textures were distinct, and similar textures were displayed in Figure 11 (Figure S21). In combinatiosn of POM and XRD, SCLCPs with analogous lv-/hv-architectures exhibited SmA, while the LC phase remained unchanged along with various topologies. However, when temperature was increased to isotropic, kept a few moments and then free cooled down, an interesting phenomenon was observed via POM (500 and 200 μm), the texture aggregation arrangement was different distinctly between hv-Lc-SCLCPs and hv-Sc-SCLCPs in Figure 11. (500 and 200 μm), with a similar texture in 50 μm images. It was demonstrated that Lc-/Sc-SCLCPs exhibited SmA via high power field POM (50 μm), while the aggregation state of macromolecular chains observed by 500 and 200 μm POM on free cooling without any external force was arranged and controlled by interaction forces from macromolecular side chains. Accordingly, the macromolecular side chains packing model was employed (Figure 9). For hv-Lc-SCLCPs, the aggregation state of macromolecular chains aggregated or grew up as similar columnar-like, while for hv-Sc-SCLCPs, the aggregation state grew up as a sphere shape. The phenomenon verified speculation of a sphere-shape for Sc-SCLCPs. Thermal Properties. The DSC curve of Chol-vinyl(IM) showed a Tm at 117 °C and a cholestetic−isotropic phase transition (Tci) at 246 °C on heating, and displayed an Tic at 245 °C and Tc at 138 °C on cooling (ΔT = 129 °C), corresponding with the previous report,60 as shown in Figure M


Article

Macromolecules

Figure 11. POM (a, b) 500 μm, (c, d) 200 μm, and (e−h)50 μm; typical fan-shaped texture images of hv-SCLCPs (1), POM of hv-Lc-SCLCPs (2), POM of hv-Sc-SCLCPs (3), and (d′) 200 μm, representative POM images comparison of hv-Lc-SCLCPs and hv-Sc-SCLCPs.

example, lv-Sc-SCLCPs have good film-formation for further research. Comparing lv-Sc-SCLCPs and Lc counterparts (Figure 13a), generally Sc topology led to shorter ΔT but lower Tg, demonstrating that the interpenetration force of lvLc-SCLCPs stabilized LC phase intended to increase ΔT, but meanwhile decreased the Tg. hv-PB was used to obtain SCLCPs with high EA(total), more −SiMe2OSiMe2− units were introduced to polymers, similar to many methylsiloxane-block-butadiene units connecting, which would be favorable to generate a wide ΔT and desired to decrease Tg due to increased side chains interaction force and increased free volume of side chains, respectively. Comparing lv-SCLCPs and hv-SCLCPs analogues (shown in Table 3), hvSCLCPs presented higher Tg and wider ΔT, indicating that side chains interaction force resulting from high EA(total) withholds the free volume of side chains resulting from many −SiMe2OSiMe2− units. Increased interaction force of adjacent side chains could also stabilize the LC phase, so a higher interpenetration force did not completely lead to a wider ΔT, such as lv-Lc-SCLCPs and hv-Lc-SCLCPs, while a smaller dspacing led to a wider ΔT. For hv-SCLCPs, DSC curves on the second heating cycle are shown in Figure 12(2) (corresponding cooling DSC curves are seen in Figure S23). The corresponding phase transition temperatures were summarized in Table S5. The ΔT

comparison of hv-Lc-SCLCPs and hv-Sc-SCLCPs was displayed in Figure 13b. Tg values were almost the same without being controlled by topology, because the highly EA(total) made side chains withhold free movement of backbones surrounded compactly by side chains, which tended to affect Tg indistinctly. However, surprisingly, hv-Sc-SCLCPs presented a wider ΔT than hv-Lc-SCLCPs with the same composition (Figure 13b), which was just contrary to the lv-SCLCPs systems and provided a new view for us, similar to research that dendritic or topological systems led to a shorter ΔT compared with Lc analogues.38,39 For hv-Lc-SCLCPs, the phenomenon that compacted side chains were interpenetrative between macromolecules just like lv-Lc-SCLCPs was constrained by the small domain spacing of side chains, so that LC phase was stabilized by interaction force of adjacent side chains from individual macromolecule. However, for hv-Sc-SCLCPs, according to the molecular side chains packing model from X-ray (Figure 9), side chains on the surface of the sphere crossed over inside various macromolecules. In addition, side chains close to the center of the sphere from different branched arms interpenetrated. So the LC phase of hv-Sc-SCLCPs was stabilized by cooperative macromolecular side chains penetration force from various macromolecules and different branched arms of the same molecules, which was inclined to increase ΔT. N


Article

Macromolecules

Figure 12. DSC curves on the second heating cycle (10 °C/min) of different molecular weight SCLCPs with various topologies: (1) (a) lv-LcSCLCPs, (b) lv-Lc-SCLCPs; (2) (a) hv-Lc-SCLCPs, (b) hv-Sc-SCLCPs.

Figure 13. ΔT values comparison for Tables S5 and S6 in a column chart of SCLCPs with analogous composition: (a) lv-Lc-SCLCPs and lv-ScSCLCPs; (b) hv-Lc-SCLCPs and hv-Sc-SCLCPs.

It has been found that EA of hv-SCLCPs increased under the reaction T at 60 °C, which was verified aforementioned. In fact, ΔT also increased (Table S5), likewise confirming that LC phase could be stabilized by interaction force of adjacent side chains from the same macromolecule. However, compared hvLc-SCLCPs obtained under the reaction T at 60 °C with hv-ScSCLCPs, ΔT values of the former were also shorter than that of latter, demonstrating that interpenetration force of side chains from different macromolecules played a decisive role on ΔT.

Thermal properties analysis confirmed the speculation of macromolecular side chains packing model, and the model was used better to illustrate the effects of various topologies on phase transitions and the difference in molecular microstructures and phase transitions of analogous architectures. The monophase could be stabilized by not only the interaction force of adjacent side chains from same macromolecule but also mainly the interpenetration force of side chains from various branched arms or macromolecules. A higher layer order (stronger Bragg intensity) or interpenetration force did not O


Article

Macromolecules completely lead to a wider ΔT, however; in general, a smaller dspacing value led to a wider ΔT. The thermal stabilities of obtained SCLCPs were analyzed with TGA under a nitrogen atmosphere; the results were summarized in Tables S4 and S5. TGA thermograms of SCLCPs were displayed in Figure S23. The polymers showed a high thermal stability with decomposition temperatures (Td) at 5% weight loss occurred higher than 300 °C without being controlled by topologies backbones.

interaction force of adjacent side chains and interpenetration force, and a higher layer order (stronger Bragg intensity) did not completely led to a wider ΔT. Recorded by POM, combining with X-ray, SCLCPs exhibited the same smectic A phase around room temperature, although the phase type remained unchanged and the always lamellar layer order structure was controlled by topology. On the fundamental side, the differences of macromolecular aggregation arrangement in LC state dependent on free cooling between hv-Lc-SCLCPs and hv-Sc-SCLCPs were observed in POM (500 and 200 μm) for the first time, which revealed sphere speculation of the Sc macromolecule. All obtained SCLCPs exhibited a wide ΔT (mostly higher than 100 °C) and showed a high thermal stability in consideration of the decomposition temperatures at 5% weight loss occurring greater than 300 °C without being controlled by topological backbones due to mesomorphic moieties.

■

CONCLUSIONS We detailed the synthesis and characterization of effectivedefined lv-Lc/Sc-SCLCPs and hv-Lc/Sc-SCLCPs with various molecular weights. Siloxane-conraining mesomorphic moiety was incorporated to high 1,2 or high 1,4 analogues. On the basis of characterization analysis from 1H NMR, the EA of PBs attached by mesomorphic moieties was evaluated. Evidence demonstrated that suspended vinyl from PBs was favored to react, and by comparison, 1,2-olefines had a higher kinetic constant than 1,4-olefines, hence 1,2-olefines had a higher EA when elevating the reaction temperature. Topological constraint arising from a branched system profoundly affected the EA, so incomplete addition was always obtained. In two analogous hv-/lv-architectures, both with Lc and Sc topology, a macromolecular side chains packing model was constructed to study the unique difference in LC microstructures and properties. In addition, it provided a unique opportunity to study the relationship of structure−property on the basis of well-defined side attachment densities. In combination of X-ray analysis and 1H NMR calculation, we speculated the model of two analogous architectures. Sc-SCLCPs were like a sphereshape, while Lc-SCLCPs were like a columnar-shape. The phase transitions analysis confirmed the model. The effects of various topologies on molecular microstructures and phase behavior were systematically investigated. Topological constraint arising from branched structures affected phase behavior and microstructures, and this topological effect was more prominent for smaller molecular weight SCLCPs. For lvSCLCPs, the backbones were surrounded loosely by side chains. lv-Lc-SCLCPS with interpenetrative side chains exhibited a higher layer order (stronger Bragg intensity), smaller d-spacing, and wider ΔT than Sc-counterparts, which contained side chains constrained inner sphere and dispersing on different branched arms. Topological effects arising from Sc structures profoundly affected macrostructures and phase transitions, effectively accounting for lv-SCLCPs, while a contrary trend was depicted for hv-SCLCPs, as compared with hv-Lc-SCLCPs. hv-Sc-SCLCPs exhibited a higher layer order (the strongest Bragg intensity), smaller d-spacing value, and wider ΔT, which provided us a new analytic model that is of interest to be explored. Backbones of hv-Lc-SCLCPs were surrounded compactly by side chains, mainly generated interaction force of adjacent side chains, while hv-Sc-SCLCPs not only generated interpenetration force from various branched arms closed to the center of the sphere but also generated interpenetration force of side chains out of the sphere from various macromolecules. Additionally, as compared with hv-Lc-SCLCPs, lv-Lc-SCLCPs exhibited a higher Bragg intensity and a shorter ΔT. The results revealed that the molecular microstructures and phase behavior were controlled by various topologies, the Bragg intensity was determined by the interpenetration force, while the d-spacing values and phase behavior were determined by cooperative interplay between

■

ASSOCIATED CONTENT

* Supporting Information S

Related characterization results that were referred to in the text, including 1H NMR, WAXD, 2D SAXS, POM, GPC, DSC, and TGA plots, a picture of the molecualr model of Chol-SiH(M), some powder WAXD data summarized in tablular form, related calculation equations from 1H NMR, thermal properties data, and partial FT-IR absorption peak assignment. This material is available free of charge via the Internet at http://pubs.acs.org.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected] (Y.L.). Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was financially supported by by National Science Fundation of China (No. 21034001 and No. 21304013), and National Program on Key Basic Research Project (973 Program No. 2015CB654701).

■

REFERENCES

(1) Ikeda, T.; Tsutsumi, O. Science 1995, 268, 1873−1875. (2) Yu, Y. L.; Nakano, M.; Ikeda, T. Nature 2003, 425, 145. (3) Yamada, M.; Kondo, M.; Mamiya, J.; Yu, Y. L.; Kinoshita, M.; Barrett, C. J.; Ikeda, T. Angew. Chem., Int. Ed. 2008, 47, 4986−4988. (4) Buguin, A.; Li, M. H.; Silberzan, P.; Ladoux, B.; Keller, P. J. Am. Chem. Soc. 2006, 128, 1088−1089. (5) Xia, Y.; Verduzco, R.; Grubbs, R. H.; Kornfield, J. A. J. Am. Chem. Soc. 2008, 130, 1735−1740. (6) Ohm, C.; Kapernaum, N.; Nonnenmacher, D.; Giesselmann, F.; Serra, C.; Zentel, R. J. Am. Chem. Soc. 2011, 133, 5305−5311. (7) Jiang, Z.; Xu, M.; Li, F. Y.; Yu, Y. L. J. Am. Chem. Soc. 2013, 135, 16446−16453. (8) Marshall, J. E.; Gallagher, S.; Terentjev, E. M.; Smoukov, S. K. J. Am. Chem. Soc. 2014, 136, 474−479. (9) Xie, H. L.; Liu, Y. X.; Zhong, G. Q.; Zhang, H. L.; Chen, E. Q.; Zhou, Q. F. Macromolecules 2009, 42, 8774−8780. (10) Liu, L. M.; Liu, K. P.; Dong, Y. P.; Chen, E. Q.; Tang, B. Z. Macromolecules 2010, 43, 6014−6023. (11) Wang, L. Y.; Tsai, H. Y.; Lin, H. C. Macromolecules 2010, 43, 1277−1288. (12) Galli, G.; Baldini, A.; Chiellini, E.; Gallot, B. Mol. Cryst. Liq. Cryst. 2005, 441, 227−235. P


Article

Macromolecules (13) del Barrio, J.; Blasco, E.; Toprakcioglu, C.; Koutsioubas, A.; Scherman, O. A.; Oriol, L.; Somolinos, C. S. Macromolecules 2014, 47, 897−906. (14) Prehm, M.; Diele, S.; Das, M. K.; Tschierske, C. J. Am. Chem. Soc. 2003, 125, 614−615. (15) Liu, F.; Chen, B.; Baumeister, U.; Zeng, X. B.; Ungar, G.; Tschierske, C. J. Am. Chem. Soc. 2007, 129, 9578−9579. (16) Barberá, J.; Donnio, B.; Gehringer, L.; Guillon, D.; Marcos, M.; Omenat, A.; Serrano, J. L. J. Mater. Chem. 2005, 15, 4093−4105. (17) Canilho, N.; Kasemi, E.; Schluter, A. D.; Ruokolainen, J.; Mezzenga, R. Macromolecules 2007, 40, 7609−7616. (18) Zhang, L. Y.; Chen, S.; Zhao, H.; Shen, Z. H.; Chen, X. F.; Fan, X. H.; Zhou, Q. F. Macromolecules 2010, 43, 6024−6032. (19) Petr, M.; Hammond, P. T. Macromolecules 2011, 44, 8880− 8885. (20) Asaoka, S.; Uekusa, T.; Tokimori, H.; Komura, M.; Iyoda, T.; Yamada, T.; Yoshida, H. Macromolecules 2011, 44, 7645−7658. (21) Komiyama, H.; Sakai, R.; Hadano, S.; Asaoka, S.; Kamata, K.; Iyoda, T.; Komura, M.; Yamada, T.; Yoshida, H. Macromolecules 2014, 47, 1777−1782. (22) Kubo, S.; Kobayashi, S.; Hadano, S.; Komura, M.; Iyoda, T.; Nakagawa, M. Jpn. J. Appl. Phys. 2014, 53, 06JC04. (23) Politakos, N.; Weinman, C. J.; Paik, M. Y.; Sundaram, H. S.; Ober, C. K.; Avgeropoulos, A. J. Polym. Sci., Polym. Chem. 2011, 49, 4292−4305. (24) Mysliwiec, J.; Czajkowski, M.; Miniewicz, A.; Bartkiewicz, S.; Kochalska, A.; Polakova, L.; Sedlakova, Z.; Nespurek, S. Opt. Mater. 2011, 33, 1398−1404. (25) Zhao, Y.; Bai, S. Y.; Asatryan, K.; Galstian, T. Adv. Funct. Mater. 2003, 13, 781−788. (26) Wang, B.; Ma, H. W.; Wang, Y. S.; Li, Y. Chem. Lett. 2013, 42, 915−917. (27) Wen, G. H.; Zhang, B.; Xie, H. L.; Liu, X.; Zhong, G. Q.; Zhang, H. L.; Chen, E. Q. Macromolecules 2013, 46, 5249−5259. (28) Zheng, J. F.; Liu, X.; Chen, X. F.; Ren, X. K.; Yang, S.; Chen, E. Q. ACS Macro Lett. 2012, 1, 641−645. (29) Zhuang, B. L.; Wang, Z. G. Macromolecules 2012, 45, 6220− 6229. (30) Yang, H.; Liu, M. X.; Yao, Y. W.; Tao, P. Y.; Lin, B. P.; Keller, P.; Zhang, X. Q.; Sun, Y.; Guo, L. X. Macromolecules 2013, 46, 3406− 3416. (31) Soininen, A. J.; Tanionou, I.; ten Brummelhuis, N.; Schlaad, H.; Hadjichristidis, N.; Ikkala, O.; Raula, J.; aele Mezzenga, R.; Ruokolainen, J. Macromolecules 2012, 45, 7091−7097. (32) Osuji, C. O.; Chen, J. T.; Mao, G.; Ober, C. K.; Thomas, E. L. Polymer 2000, 41, 8897−8907. (33) Osuji, C.; Ferreira, P. J.; Mao, G.; Ober, C. K.; Vander Sande, J. B.; Thomas, E. L. Macromolecules 2004, 37, 9903−9908. (34) Xiang, M. L.; Li, X. F.; Ober, C. K.; Char, K.; Genzer, J.; Sivaniah, E.; Kramer, E. J.; Fischer, D. A. Macromolecules 2000, 33, 6106−6119. (35) Wang, J. G.; Mao, G. P.; Ober, C. K.; Kramer, E. J. Macromolecules 1997, 30, 1906−1914. (36) Kasko, A. M.; Heintz, A. M.; Pugh, C. Macromolecules 1998, 31, 256−271. (37) Liu, L. M.; Zhang, B. Y.; He, X. Z.; Cheng, C. S. Liq. Cryst. 2004, 31, 781−786. (38) Han, D. H.; Tong, X.; Zhao, Y.; Galstian, T.; Zhao, Y. Macromolecules 2010, 43, 3664−3671. (39) Ganicz, T.; Pakula, T.; Fortuniak, W.; Florjańczyk, E. B. Polymer 2005, 46, 11380−11388. (40) Zubarev, E. R.; Talroze, R. V.; Yuranova, T. I.; Plate, N. A.; Finkelmann, H. Macromolecules 1998, 31, 3566−3570. (41) Xu, Z. T.; Kiang, Y. H.; Lee, S.; Lobkovsky, E. B.; Emmott, N. J. Am. Chem. Soc. 2000, 122, 8376−8391. (42) Saez, I. M.; Goodby, J. W. J. Mater. Chem. 2003, 13, 2727−2739. (43) Barberá, J.; Donnio, B.; Gehringer, L.; Guillon, D.; Marcos, M.; Omenatand, A.; Serrano, J. L. J. Mater. Chem. 2005, 15, 4093−4105.

(44) Ge, J. J.; Hong, S. C.; Tang, B. Y.; Li, C. Y.; Zhang, D.; Bai, F.; Mansdorf, B.; Harris, F. W.; Yang, D.; Shen, Y. R.; Cheng, S. Z. D. Adv. Funct. Mater. 2003, 13, 718−725. (45) Pastor, L.; Barberá, J.; McKenna, M.; Marcos, M.; Rapún, R. M.; Serrano, J. L.; Luckhurst, G. R.; Mainal, A. Macromolecules 2004, 37, 9386−9394. (46) Xing, X. J.; Shin, H.; Bowick, M. J.; Yao, Z. W.; Jia, L.; Li, M. H. Proc. Natl. Acad. Sci. U.S.A. 2012, 109, 5202−5206. (47) Boyer, S. A. E.; Iwamoto, C.; Yoshida, H. J. Therm. Anal. Calorim. 2013, 113, 1565−1576. (48) Chang, X.; Dong, C. M. Biomacromolecules 2013, 14, 3329− 3337. (49) Tomatsu, I.; Fitié, C. F. C.; Byelov, D.; de Jeu, W. H.; Magusin, P. C. M. M.; Wübbenhorst, M.; Sijbesma, R. P. J. Phys. Chem. B 2009, 113, 14158−14164. (50) Sato, M.; Kobayashi, Y.; Shimizu, T.; Yamaguchi, I. Polym. Chem. 2010, 1, 891−898. (51) Rao, V. S.; Samui, A. B. J. Polym. Sci., Polym. Chem. 2011, 49, 1319−1330. (52) Rapún, R. M.; Marcos, M.; Omenat, A.; Barberá, J.; Romero, P.; Serrano, J. L. J. Am. Chem. Soc. 2005, 127, 7397−7403. (53) Zhang, X. R.; Richter, L. J.; DeLongchamp, D. M.; Kline, R.; Hammond, M. R.; McCulloch, I.; Heeney, M.; Ashraf, R. S.; Smith, J. N.; Anthopoulos, T. D.; Schroeder, B.; Geerts, Y. H.; Fischer, D. A.; Toney, M. F. J. Am. Chem. Soc. 2011, 133, 15073−15084. (54) Zhang, H. X.; Li, Y.; Zhang, C. Q.; Li, Z. S.; Li, X.; Wang, Y. R. Macromolecules 2009, 42, 5073−5079. (55) Zhang, Y.; Shen, K. H.; Guo, F.; Wang, Y. F.; Wang, Y. S.; Wang, Y. R.; Li, Y. RSC Adv. 2013, 3, 20345−20352. (56) Zhang, Y.; Guo, F.; Shen, K. H.; Ren, Y. Y.; Li, Y. Polymer 2014, 55, 1202−1208. (57) Yang, H.; Jia, L.; Zhu, C. H.; Cicco, A. D.; Levy, D.; Albouy, P. A.; Li, M. H.; Keller, P. Macromolecules 2010, 43, 10442−10451. (58) Kašpar, M.; Bubnov, A.; Sedláková, Z.; Stojanović, M.; Havlíček, J.; Obadović, D. Z.; Ilavský, M. Eur. Polym. J. 2008, 44, 233−243. (59) Jigounov, A.; Sedláková, Z.; Kripotou, R.; Pissis, P.; Nedbal, J.; Baldrian, J.; Ilavský, M. Polymer 2007, 48, 5721−5733. (60) Wang, B.; Ma, H. W.; Shen, K. H.; Ding, J.; Li, Y. Chin. Chem. Lett. 2012, 23, 1419−1422. (61) Meng, F. B.; Zhang, B. Y.; Liu, L. M.; Zang, B. L. Polymer 2003, 44, 3935−3943. (62) Yang, H.; Jia, L.; Zhu, C. H.; Cicco, A. D.; Levy, D.; Albouy, P. A.; Li, M. H.; Keller, P. Macromolecules 2010, 43, 10442−10451. (63) Verploegen, E.; Zhang, T.; Murloand, N.; Hammond, P. T. Soft Matter 2008, 4, 1279−1287. (64) Wang, L. Y.; Tsai, H. Y.; Lin, H. C. Macromolecules 2010, 43, 1277−1288. (65) Wang, J. W.; Zhang, B. Y. Colloid Polym. Sci. 2013, 291, 2917− 2925. (66) Li, Y. W.; Zhang, W. B.; Janoski, J. E.; Li, X. P.; Dong, X. H.; Wesdemiotis, C.; Quirk, R. P.; Cheng, S. Z. D. Macromolecules 2011, 44, 3328−3337. (67) Liu, B. X.; Quirk, R. P.; Wesdemiotis, C.; Yol, A. M.; Foster, M. D. Macromolecules 2012, 45, 9233−9242. (68) Zhuang, B. L.; Wang, Z. G. Macromolecules 2012, 45, 6220− 6229. (69) Lotti, L.; Coiai, S.; Ciardelli, F.; Galimberti, M.; Passagalia, E. Macromol. Chem. Phys. 2009, 210, 1471−1483.

Q


Construction of Topological Macromolecular Side Chains Packing

Recommend Documents