Formation of Diverse Ordered Structures in ABC ... - ACS Publications

Article Cite This: Macromolecules XXXX, XXX, XXX−XXX

Formation of Diverse Ordered Structures in ABC Triblock Terpolymer Templated Macroporous Silicas Xin Cao,† Wenting Mao,† Yiyong Mai,† Lu Han,*,†,‡ and Shunai Che*,†,‡ †

School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China ‡ School of Chemical Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China S Supporting Information *

ABSTRACT: The macroporous silica synthesis system with the ABC triblock terpolymer poly(ethylene oxide)-block-polystyrene-block-poly(tert-butyl acrylate) (denoted as OSA) as template and tetraethyl orthosilicate as silica source under acidic conditions in a mixture solvent of tetrahydrofuran and H2O has been investigated, and two synthesis−field phase diagrams are plotted. Eight different structures varied from normal-phase (oil in water) cage-type (n-C), normal-phase 2D hexagonal (n-H), and lamellar (L) to unique inverse-phase (water in oil) hyperbolic-surface (i-HS) structures, including the shifted double-diamond (i-SDD), single-gyroid (i-SG), and shifted double-primitive (i-SDP), inverse-phase 2D hexagonal (i-H) and inverse-phase micellar (i-M) structures, have been formed by varying the degree of polymerization of the hydrophobic blocks in OSA. From the two-component phase diagram, it can be concluded that the macroporous structures formation is affected by the packing parameter p and the segregation product (χN) of the hydrophilic and hydrophobic blocks. With an increase in p, the structures n-C and n-H were found in the range of low χN, whereas the structures i-HS, i-H, and i-M were found in the range of higher χN, while L is in between. In the threecomponent phase diagram, different volume fraction ratios (VFR) of the hydrophobic/hydrophilic block (S/O, A/O) and those of hydrophobic/hydrophobic block (S/A) in this co-assembly system divided the resultant ordered structures in various regions. The n-C, n-H, and L structures were found in low VFRs of S/O and A/O; i-H and i-M structures were formed in high VFRs of S/O and A/O. The formations of the i-HS structures including i-SDD, i-SDP, and i-SG are depending on low VFRs regions of S/ O and S/A with similar packing parameter.

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INTRODUCTION

Up to now, the co-assembly method has been extensively studied in the “simplest” AB diblock or ABA triblock terpolymer systems to produce mesostructured materials, and the relative structure diagrams have been constructed and renewed for several times.16−20 Of note, diverse mesoporous inorganic materials have been synthesized by employing BCPs as template, in which the inorganic species interact with one block of the polymers through hydrogen bonding, van der Waals force, or electrostatic interactions to give rise to the microphase separation, such as poly(ethylene oxide)-blockpolyisoprene (PEO-b-PI),21 poly(ethylene oxide)-block-polystyrene (PEO-b-PS),22 polyisoprene-block-poly(dimethylaminoethyl methacrylate) (PI-b-PDMAEMA),23 etc., or ABA BCPs, such as poly(ethylene oxide)20-block-poly(propylene oxide)70-block-poly(ethylene oxide)20 (Pluronic P-123),24 poly(ethylene oxide)106-block-poly(propylene oxide)70-block-poly(ethylene oxide)106 (Pluronic F-127),25 etc. Meanwhile, the materials with different inorganic compositions such as

Ordered macroporous materials are predicted to be utilized as catalyst supporters, adsorbents, chromatography of proteins, filters, lightweight structural materials, thermal, acoustic, and electrical insulators,1−8 etc. Specially, as their pore diameters are comparable to optical wavelengths, the macroporous materials have drawn lots of attention for their unique and highly useful optical properties such as photonic bandgaps and optical stop bands.8 Enormous methods such as self-assembled molecular aggregates or supramolecular assemblies templating routes, hard templating routes, and lithography have been developed for producing macroporous materials.9−13 It is still worthwhile to notice that there remains a great challenge in synthesizing porous materials with designed porous structures in larger scales, especially with the triply periodic hyperbolicsurface structures. The co-assembly of block copolymers (BCPs) and inorganic species in solution has attracted great interests due to the gigantic volume of polymer molecules in contrast to that of small molecules, the ability to form a wide variety of complicated structures, and the enhanced physical and chemical properties owing to the addition of inorganic species.14,15 © XXXX American Chemical Society

Received: February 1, 2018 Revised: May 21, 2018

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DOI: 10.1021/acs.macromol.8b00242 Macromolecules XXXX, XXX, XXX−XXX

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Macromolecules silicate,21,26,27 transition metal oxide,24 and pure metal28 have been produced. By adding an additional block to AB diblock copolymer to form an ABC triblock terpolymer, the microphase separation behavior of the polymers can be significantly enriched due to the increased number of interaction parameters and the diversity of the block types.29 Using ABC triblock terpolymer rather than AB diblock as template has shown the great potential to produce inorganic material.30−32 Stucky et al.24 reported a generalized synthesis of large-pore mesoporous metal oxides with various compositions and mixed oxides by using P-123 as surfactant coassembled with diverse inorganic resources. Wiesner et al.21,33−36 pioneered in linking the inorganic chemistry to the BCPs with high molecular weight as structure-directing agents for several inorganic scaffolds. Snaith et al.37,38 prepared the synthesis of mesoporous TiO2 film using as photoanodes of dye-sensitized solar cells. Steiner et al. reported a series of inorganic materials in self-assembled polymeric templates for various applications.39−41 Lin et al.39−50 innovatively synthesized monodisperse nanocrystal with various compositions and architectures by using starlike copolymers with well-defined structures and narrow molecular weight distributions as nanoreactors. In solution, BCPs behave in an analogous fashion to smallmolecule lipids with a greater length scale. It is primarily the packing parameter, p = v/a0lc, that determines the structure formation, where v is the volume of the hydrophobic segment, a0 is the molecular area of the hydrophilic headgroup, and lc is the length of the hydrophobic segment.54 Typically, in normal structures, when p < 1/3, spheres are formed; when 1/3 < p < 1/2, cylindrical structures; when 1/2 < p < 2/3, bicontinuous hyperbolic structures; when 2/3 < p < 1, flexible lamellae or vesicles; and finally, when p = 1, planar lamellae are obtained. If p > 1, the corresponding inverse structures can be obtained. The packing parameter is generally affected and determined by the volume fractions of different blocks. These structures can be obtained by increasing the volume fraction of the hydrophobic moiety to attain the proper packing parameter. Especially, the unique hyperbolic-surface structures formed in the triblock system have a much wider structure composition window (86− 96 vol % of f hydrophobic)55,56 than the structures found in diblock system (94−98 vol % of f hydrophobic).57 On the other hand, the microphase separation of the BCPs leads to the typical length scale of 5−100 nm;58,59 the mesoporous inorganic materials with ultralarge pores and the macroporous materials templated by BCP co-assembly with inorganic species in solution have been rarely documented. It is worthy to note that the length scale of the structure is generally dependent on the size of the polymer chains; therefore, high molecular weight BCPs are desired for the synthesis of materials with large unit cells. However, the copolymer with high molecular weight would have exceptionally high polydispersity and exhibit very slow self-assembly kinetics.60 To the best of our knowledge, the microphase separation of PSb-PI with a molecular weight of ∼750 kg/mol into the so far largest 3D gyroid structure with a unit cell parameter of a = 258 nm required a two-week casting process.61 Recently, we developed a delicate method using AB or ABC BCPs as template in a mixture of a common solvent, tetrahydrofuran (THF), and a selective solvent, water. In this synthesis system, all blocks are soluble in THF. However, when a small amount of water is added, the microphase separation occurs. The hydrophobic blocks only present in the THF-rich

phase, whereas water is driven out of the hydrophobic segments and mainly presents in the hydrophilic core. As the template molecules only dispersed at the interface of THF and water, the whole structure can be swelled by a large amount of solvent. Therefore, the macroporous materials with a length scale of several hundred nanometers can be formed by BCPs. By using this method, macroporous inorganic materials with inverse shifted double-diamond (i-SDD) silica with unit cell parameter up to 340 nm (c-axis of i-SDD),12 single-gyroid (i-SG) silica,62 and shifted double-primitive (i-SDP) silica27 have been synthesized. To understand the structural control and their co-existing relationship in this self-assembly system, it is really profound to investigate the distribution of these unique structures systematically in the OSA polymer co-assembly with inorganic species in solution. Herein, 108 ABC triblock terpolymer poly(ethylene oxide)-block-polystyrene-block-poly(tert-butyl acrylate) (PEO117-b-PSn-b-PtBAm, denoted as OSA) with a hydrophilic−hydrophobic−hydrophobic sequence were designed and synthesized, which have different total degrees of polymerization (DPs) (N) and DPs of block A and S (NA, NS) as well as a fixed DP of PEO block (NO). We presented two synthesis−field phase diagrams, including the twocomponent diagram (χN versus the volume fraction of the hydrophobic blocks fA+S) and three-component diagram differed from different volume fraction ratios (VFRs) of block S/O, A/O, and S/A. Eight structures, including normal-phase cage-type (n-C), normal-phase 2D hexagonal (n-H), lamellar (L), unique inverse-phase hyperbolic-surface (i-HS, including iSG, i-SDD, and i-SDP), inverse-phase 2D hexagonal (i-H), and inverse-phase micellar (i-M) structures, have been obtained. The structural solutions were conducted using small-angle Xray scattering (SAXS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The relationship of the blocks in the OSA terpolymers for the synthesis of various structures was investigated.

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EXPERIMENTAL SECTION

Chemicals. Triethylamine, dimethylpyridine, (99%, Transoole Reagent Co., Ltd.), tetraethyl orthosilicate (TEOS, 98%, TCI), 2bromoisobutyryl bromide (98%, TCI), 1,1,4,7,7-pentamethyldiethylenetriamine (PMEDTA, 98%, TCI), copper bromide (CuBr, 97%, Sinopharm Chemical Reagent Co., Ltd.), diethyl ether anhydrous (99%, Sinopharm Chemical Reagent Co. Ltd.), hydrochloric acid (HCl, 36%, Sinopharm Chemical Reagent Co., Ltd.), methanol (99%, Sinopharm Chemical Reagent Co., Ltd.), petroleum ether (60-90, Sinopharm Chemical Reagent Co., Ltd.), tetrahydrofuran (THF, 99%, Sinopharm Chemical Reagent Co., Ltd.), and deionized water (MilliQ, 18.2 MΩ·cm) were used without further purification. tert-Butyl acrylate (t-BA) (97%, TCI), the polymerization inhibitor, was removed by an alkaline alumina column. Styrene (99%, Sinopharm Chemical Reagent Co., Ltd.), the polymerization inhibitor, was removed by 20% sodium hydroxide solutions, dried with anhydrous magnesium sulfate, and finally distilled under reduced pressure before use. Methyl poly(ethylene oxide) with a hydroxyl terminal group (PEO-OH 5000) at one end was purchased from Aldrich (Mn,GPC = 5.17 × 103 g/mol, PDI = 1.12, labeled as PEO117). Synthesis of the Macroinitiator PEO117-Br. PEO117-Br was introduced through the esterification of PEO117-OH with 2bromoisobutyryl bromide in THF. First, PEO117-OH (90.0 g, 17.4 mmol) was dissolved in dry THF (200 mL). To the solution were added 2.5 mL of triethylamine and 3.0 g of dimethylpyridine. After the solution was stirred for 30 min while being cooled in an ice−water bath, 2-bromoisobutyryl bromide (20.0 g, 87.1 mmol) was added to the solution over a period 1 h under N2 protection. Finally, the B


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Macromolecules solution was stirred at room temperature for 12 h and then filtrated to obtain a homogeneous solution. Subsequently, 500 mL of cold ether was added to the solution to obtain a white precipitate. The precipitate was filtered and washed several times with cold ether. After the precipitate was dried under vacuum, the macroinitiator PEO117-Br was obtained. 1H NMR (CDCl3), δ (ppm): 3.30 (s, 3H, −OCH3), 3.40− 3.70 (m, 4H, −CH2CH2−O− of PEO chain), 3.80 (m, H, H−O− of the end PEO chain) (see Figure S1 in the Supporting Information). Synthesis of PEO117-b-PSn-Br. PEO117-b-PSn-Br was prepared via the atom-transfer radical polymerization (ATRP) of styrene using PEO117-Br as the initiator under the CuBr/1,1,4,7,7-pentamethyldiethylenetriamine (PMEDTA) catalyst system (see Figure S2). A 250 mL Schlenk flask containing 10.0 g of PEO117-Br (1.88 mmol), 1.18 mL of PMDETA (5.64 mmol), and 50.0 g of styrene (0.29 mol) was purged thoroughly and then sealed with a rubber stopper. After the solution became clear while being stirred, 0.27 g of CuBr (1.88 mmol) was added to the solution. The flask containing the reactants was fully degassed with a minimum of four freeze−pump−thaw cycles and sealed under vacuum. The flask was subsequently placed in a 110 °C oil bath to allow the polymerization to proceed. Several hours later, the reaction mixture was cooled to room temperature. The polymerization was terminated by exposing the reaction mixture to air. The catalyst was removed by filtration through neutral alumina using methylene chloride as the eluent. The polymer was obtained by precipitation using cold methanol (500 mL) and was subsequently dried under vacuum. The Mn and PDI of PEO117-b-PSn-Br can be obtained from GPC (see Figure S3). The amount of polystyrene (PS) segment was calculated to be n. 1H NMR (CDCl3), δ (ppm): 3.30 (s, 3H, −OCH3), 3.40−3.70 (m, 4H, −CH2CH2−O− repeating unit of PEO main chain), 1.31 (s, 6H, −C(CH3)2−PS), 1.50−1.99 (m, 3H, −CH2CH(Ph)− repeating unit of PS main chain), 3.40−3.60 (m, 2H, −CH(Ph)CH2−Br end group of PS main chain), 6.30−7.30 (m, 5H, −C6H5 of PS main chain) (see Figure S1). Synthesis of PEO117-b-PSn-b-PtBAm. PEO117-b-PSn-b-PtBAm was synthesized by the ATRP of tert-butyl acrylate (t-BA) using PEO117-bPSn-Br as the initiator under the CuBr/PMEDTA catalyst system (see Figure S2). A 250 mL Schlenk flask containing 10.0 g of PEO117-b-PSnBr (0.89 mmol), 0.56 mL of PMDETA (2.67 mmol), 25 mL of N,Ndimethylformamide (DMF), and 50 mL of t-BA was purged thoroughly and then sealed with a rubber stopper. After the solution became clear while being stirred, 0.128 g of CuBr (0.89 mmol) was added to the solution. The flask was fully degassed with a minimum of four freeze−pump−thaw cycles and sealed under vacuum. The flask was subsequently placed in a 70 °C oil bath for approximately 6 h. The products were treated as described in the preparation of PEO117-b-PSnBr. The Mn and PDI of PEO117-b-PSn-b-PtBAm-Br can also be obtained from GPC (see Figure S3). 1H NMR(CDCl3), δ (ppm): 3.30 (s, 3H, −OCH3), 3.40−3.70 (m, 4H, −CH2CH2−O− repeating unit of PEO main chain), 1.27 (s, 6H, −C(CH3)2−PS), 1.50−2.21 (m,3H, −CH2CH(Ph)− repeating unit of PS main chain), 1.49−1.60 (m, 11H, −CH(COOC(CH3)3)CH2− repeating unit of PtBA main chain), 2.88−3.37 (m, 1H, −CH(COOC(CH3)3)CH2− repeating unit of PtBA main chain), 3.70−3.80 (m, 2H, −CH(COOC(CH3)3)CH2−Br end group of PtBA main chain), 6.30−7.30 (m, 5H, −C6H5 of PS main chain) (see Figure S1). Synthesis of Macroporous Silica. The macroporous silica was prepared via evaporation-induced self-assembly (EISA) method with (PEO117-b-PSn-b-PtBAm) triblock copolymer used as the template. 2 g of HCl (2 M) was added to 12.0 g of a THF solution containing 0.3 g of OSA. After the mixture was stirred for approximately 0.5 h, 0.6 g of TEOS was finally added to the solution, and the mixture was maintained under stirring for an additional 2 h. The solvent was then allowed to completely evaporate at ambient temperature. The silica/ template composite was washed with water three times and finally freeze-dried. The as-prepared samples were calcined at 550 °C in air for 10 h to remove the template. Characterizations. The nuclear magnetic resonance (NMR) spectra were measured on a Varian Mercury Plus 400 MHz NMR spectrometer using tetramethylsilane (TMS) as the internal reference. The polymers were dissolved in deuterated chloroform (CDCl3). The

molecular weights and molecular weight distributions of the polymers were determined on a HLC-8320GPC (TOSOH Corp.) gel permeation chromatography (GPC) apparatus, and the measurements were conducted using DMF as the eluent at a flow rate of 10−2000 μL/min. The SAXS experiments were recorded by synchrotron radiation XRD at beamline BL16B1, provided from Shanghai Synchrotron Radiation Facility (SSRF). The microscopic features of the samples were observed using SEM, which was performed on a JEOL JSM-7401F and JSM-7800F Prime; the samples were observed with landing energy of 1 kV with decelerating bias of 2 and 5 kV, respectively, without any metal coating. TEM observations were performed using a JEOL JEM-2100 microscope equipped with a LaB6 gun operated at 200 kV (Cs 1.0 mm, point resolution 2.3 Å). Images were recorded using a TENGRA CCD camera (resolution of 2304 × 2304 pixels with a 2:1 fiber-optical taper and an effective pixel size of 8 μm2). The nitrogen adsorption/desorption isotherms were measured at 77 K using QuadraSorb SI analyzer. The surface area was calculated by the Brunauer−Emmett−Teller (BET) method, and the pore size was obtained from the pore size distribution curve calculated by the Barett−Joyner−Halenda (BJH) method using the adsorption branch of the isotherms of different structures and the nonlocal density functional theory (NLDFT) method.

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RESULTS AND DISCUSSION The poly(ethylene oxide)-block-polystyrene-block-poly(tertbutyl acrylate) (PEO117-b-PSn-b-PtBAm, OSA) polymers were synthesized with total molar mass in the range of 13 760−61 716 g/mol, polydispersity indices of 1.10−1.46, and volume fractions of 5.6−21.5%, 8.7−41.9%, and 44.7−77.8% for the O, S, and A blocks, respectively. The amounst of the THF solvent (8−15 g) and HCl (2 M) (0.5−4 g) were controlled precisely in the synthesis system. In a typical synthesis, 2 g of HCl (2 M) accompanied 12.0 g of a THF solution containing 0.3 g of OSA polymer has been adopted. A variable quantity of inorganic species (TEOS) (0.2−1.0 g) was used with different OSA polymers as templates, and the molar ratio of TEOS to block O is fixed to 1:1. Of note, the amount of TEOS was kept below 0.6 g to avoid the formation of disordered structure due to the insufficient interaction between the overdosed TEOS and block O. The materials were prepared with the composition ratios mentioned above and plotted as points in the synthesis−field diagrams, which is rational for investigation of structure occurrence, dependence, and conversion. In our co-assembly system, we fulfilled two synthesis−field phase diagrams of OSA polymers with eight structures. These structures were derived from 108 polymers of different molecular which were weighted by adjusting DPs of block A +S and kept the hydrophilic segment O unchanged simultaneously. Based on the ordered structures formed by these triblocks, a two-component synthesis−field diagram was obtained by plotting the segregation product χN (χ denotes the degree of incompatibility between the hydrophilic block O and the hydrophobic blocks A+S; N is the total DP) against the volume fraction (fA+S) of the hydrophobic segments (A+S). On the other hand, a three-component synthesis−field diagram was plotted by using the volume fraction of each block as one of the coordinate axes. Notably, χN used in this copolymer system was calculated from the equation χN = ∑N × Vref(δ1 − δ2)2/ RT, where Vref represents the segment reference volume (Vref = 100 cm3/mol) and δi denotes the Hildebrand solubility parameter for polymer i (see Table S1). Two-Component Diagram. A series of silica materials have been synthesized using the OSA polymers with an increasing fA+S in a χN range of 64.4−197.6. The relevant volume fractions are summarized in the range of 0.82−1.00. C


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Macromolecules The solubility parameter of block A (δA = 18.5 (J/cm3)1/2) is close to that of block S (δS = 19.3 (J/cm3)1/2) but differing from block O (δO = 21.2 (J/cm3)1/2) (Table S2). On the other hand, the χASN value of block A and S is around the weak segregation limit (χASN = 10.6, see Table S3), and these two blocks tend to form one microphase.53 Therefore, the OSA terpolymer can be simplified as an AB-type diblock copolymer with a hydrophobic block (A+S) and a hydrophilic (O) segment. In this diagram (Figure 1), points with different colors

fraction of each block (O, S, and A) is shown in Figure 2 (the entire region of the diagram is shown in Figure S4),

Figure 2. Three-component synthesis−field diagram (sectional) with structures derived from various compositions (in volume fractions) of OSA polymers system. Four regions in different gray level derived from vertex of block O covered all the composition points which present distribution of structures: n-C (black); n-H (purple); L (pink); i-HS (including i-SDD (red), i-SG (dark green) and i-SDP (blue)); iH (orange) and i-M (reseda). Ten lines started from the vertex of block A and S separate the regions into individual structure regions.

Figure 1. Two-component synthesis-field diagram (total volume fraction fA+S versus the corresponding interaction parameter χN between block O and block A+S) of structures synthesized by OSA polymers. Composition points represent eight structures in different colors: n-C (black); n-H (purple); L (pink); i-HS (including i-SDD (red), i-SG (dark green) and i-SDP (blue)); i-H (orange) and i-M (reseda). (i-SG and i-SDP structures were marked by dashed circles in i-SDD domain.)

summarizing the different structures observed in the selfassembly system. Similar to Figure 1, eight structures, namely, n-C, n-H, L, i-SDD, i-SG, i-SDP, i-H, and i-M, were observed. To illustrate the formation of different structures, several lines originated from zero points (see Figure S4) divided the diagram into several regions, which respectively indicated different VFRs of S/O, S/A, and A/O. First of all, four regions were divided by five lines derived from vertex of block O, which indicated the fixed VFR of block S/O with increasing the f S value. As shown in Figure 2, the n-C structure is formed in region 2, L and n-H are formed in region 3 and the two inverse structures i-H and i-M are located in region 4. However, the iSDD structure dispersed across from region 1 to region 3, while the i-SG and i-SDP structures are mainly in regions 2 and 3, respectively. Second, the six dashed lines (lines 1−6) derived from the zero point of block A indicated the fixed VFR of block A/O with variation of fA. Structures i-M and i-H were formed in the region between lines 1 and 2 and the region between lines 2

represent the materials with different structures derived from the OSA polymers. With increasing fA+S, the structures transformed following the order from n-C, n-H, L, i-HS, and i-H to i-M. In the meantime, structural transition also happened with increasing χN at a fixed fA+S. The fA+S and χN values for each structure mapped in Figure 1 and corresponding packing parameters have been summarized in Table 1. Three-Component Diagram. A further study of the selfassembly system was carried out to understand the effect of the volume fractions of the hydrophobic block A, S and hydrophilic block O on the resultant ordered structures. The threecomponent synthesis−field diagram based on the volume

Table 1. Range of Volume Fraction fA+S and χN Value between Hydrophobic Blocks (Block A+S) and Hydrophilic Block O in OSA Polymers, Related Packing Parameters, Space/Plane Group, Unit Cell Parameters/Size, and Wall Thickness of Different Structures structure

fA+S (%)

χN

packing parameter

space/plane group

n-C n-H L i-SDD i-SDP i-SG i-H i-M

78.5−82.3 81.5−84.7 82.9−85.0 84.1−89.5 84.4−88.9 85.6−88.2 85.0−90.6 90.9−94.4

64.4−77.1 65.3−78.0 75.4−77.5 81.7−111.8 83.6−110.8 85.7−102.3 72.8−114.7 126.2−197.6

p < 1/3 1/3 < p < 1/2 2/3 < p ≤ 1 p>1

Fm3m ̅ , P63/mmc p6mm

∼30 ∼50

I41/amd cmcm I4132

a = b ≈ 120, c ≈ 170 a = b ≈ 153, c ≈ 108 ∼70 ∼50 200−800 (size)

D

unit cell parameter (nm)

wall thickness (nm) ∼5 ∼10 ∼20 ∼8 ∼8 ∼5 ∼10 ∼50


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Macromolecules

Table 2. VFR Parameters and Volume Fractions of Hydrophilic Block O and Hydrophobic Blocks S and A of the BCPs and Related Packing Parameters Shown in Figure 2 structure

f O (%)

f S (%)

fA (%)

VFR of S/O

VFR of A/O

VFR of S/A

packing parameter

n-C n-H L i-SDD i-SG i-SDP i-H i-M

17.7−21.5 15.3−18.5 14.7−17.1 11.0−15.7 12.5−14.5 11.1−15.4 9.4−15.0 5.6−9.1

14.7−22.0 22.7−36.5 21.3−26.2 7.6−25.3 17.2−22.9 10.0−16.3 24.1−41.9 18.9−26.5

59.4−67.6 46.7−59.1 59.5−61.7 62.2−77.8 63.5−69.0 70.7−75.7 44.7−65.4 65.6−75.5

0.8−1.2 1.2−2.2

2.8−4.2 2.4−4.2 3.5−4.2 4.2−7.1

0.2−0.4 0.4−0.8 0.3−0.4 0.1−0.4 0.3−0.4 0.1−0.2 0.4−0.9 0.3−0.4

p < 1/3 1/3 < p < 1/2 2/3 < p ≤ 1 p>1

0.5−2.2 1.2−2.2 0.8−1.2 2.2−4.4

2.8−7.1 7.1−14.3

Figure 3. SAXS pattern and SEM and TEM images of the n-C structure templated by PEO117-b-PS38-b-PtBA146. (a) SAXS pattern of the n-C structure. (b) SEM image of the n-C structure taken in low magnification near [110]cub direction. (c, d) TEM images and Fourier diffractograms (FDs, insets) of the n-C structure taken from [110]cub and [112]cub directions, respectively.

Characterization of Different Structures. Herein, the various structures were characterized by SAXS, SEM, and TEM measurements. Normal Cage-Type Structure (n-C). The n-C structure can be synthesized in a typical synthesis condition mentioned above by using 13 OSA polymers as template (see Tables S1 and S4, no. 1−13, and Figure S5). The SAXS pattern (Figure 3a) of the typical n-C structure templated by PEO117-b-PS38-bPtBA146 shows a few reflections in the range of q = 0.2−0.45 nm‑1, with q2 ratio of 3:4:8:11, which can be indexed to 111, 200, 022, and 113 reflections on the basis of the cubic closepacking structure (space group Fm3̅m) with the unit cell parameter of a ≈ 47 nm. Figure 3b presents the low-magnification SEM image of the calcined sample, revealing mesopores stacking closely in bulky particles with highly ordered structure near [110]cub direction.

and 4, separately. Structure i-HS existed in the region between lines 2 and 3, in which i-SG transformed to i-SDP and both structures co-existed in i-SDD region. Besides, lines 3 and 4 separated structure L in a confined region. Finally, most of n-C (between lines 4 and 5) and all of the n-H structure were produced in the domain between lines 4 and 6. Furthermore, four dashed lines (lines 7−10) derived from the zero point of block S indicated the VFR of block S/A and f O was fixed. All composition points of i-SDP and a part of iSDD structure were divided from i-HS by lines 7 and 8. The domain consisting of lines 8 and 9 is interesting for five structures transforming from n-C, L, i-SG, and i-SDD to i-M with decreasing f O. The n-H transformed to i-H with decreasing f O and VFR of S/A. Specific distributions of three types of VFR values, volume fractions of the polymers, and corresponding packing parameters are summarized in Table 2. E


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Figure 4. SAXS pattern and SEM and TEM images of the n-H structure templated by PEO117-b-PS77-b-PtBA117. (a) SAXS pattern of the n-H structure. (b) Top view SEM images of the n-H taken in low magnification. (c, d) TEM images and FDs (insets) of the n-H structure taken from side and top views, respectively.

TEM images (Figure 4c,d) that the calcined material follows the 2D p6mm symmetry. Lamellar Structure (L). Figure 5 presents the SEM and TEM images of the calcined sample templated by PEO117-bPS70-b-PtBA142 and other three OSA polymers (see Table S1, no. 27−30, and Figure S7). Figures 5a and 5b present the SEM images of L structure, and Figure 5c shows a TEM image of a thin section of the sample. The reflection peak cannot be observed in the SAXS pattern because the stacking of the lamellae existed crookedly and the long-range ordered structure was disturbed. Inverse Hyperbolic Surface (i-HS) Structures. Inverse Shifted Double-Diamond Structure (i-SDD). The i-SDD structure can be synthesized with 37 OSA polymers (see Tables S1 and S4, no. 43−79, and Figure S8). The SAXS pattern and SEM and TEM images of the typical calcined iSDD structure derived from PEO117-b-PS50-b-PtBA165 are shown in Figure 6. The typical SAXS pattern is shown in Figure 6a. The reflections can be indexed to 101, 112 (200), 103 (121), 123 (031), 024, 231, and 035 (143) reflections with the unit cell parameters of a ≈ 120 nm and c ≈ 170 nm based on the tetragonal lattice, in which the space group has been determined to be I41/amd (No. 141). Figures 6b and 6c show the SEM images taken from different directions of i-SDD structure and reveal two sets of silica frameworks. Each silica framework is hollow with a thin silica wall thickness of ∼8 nm, which contains tetrahedral arrangements at their nodes and can be identified as diamond structures. The TEM images of i-SDD structure recorded along [111]SDD, [010]SDD, and [101]SDD

It clearly shows the intergrowth of the cubic close-packed layer (ccp, ABC stacking sequence) and the hexagonal close-packed layer (hcp, ABAB stacking sequence). The ccp and hcp structures have different stacking sequences with the same layers depending on the origin of the layers. The TEM images (Figure 3c,d) recorded along the [110]cub, [112]cub directions show the white contrast corresponds to the mesoporous areas of low electron-scattering density. Hard spheres with uniform size can be arranged to form a ccp or an hcp. The intergrowth of ccp/hcp structure packed randomly sharing the [001]hex and the [111]cub axis. The FDs show both sharp spots and streaks due to the intergrowths of ccp and hcp structures. However, in this synthesis system, it is very difficult to synthesize pure ccp or hcp phase due to the incorporation of a large amount of solvent in the synthesis, and the reaction was carried out with the solvent evaporation process. The self-assembly of the template and the inorganic source is therefore not an equilibrium process and is both thermodynamically and kinetically controlled, which makes the synthesis difficult to be fine-tuned with very precise condition. Normal 2D Hexagonal Structure (n-H). OSA polymer PEO117-b-PS77-b-PtBA117 and other 12 polymers (Table S1, no. 14−26, and Figure S6) were used to synthesize n-H structure. Figure 4a shows the SAXS pattern of the typical sample. The broaden peak was attributed to the short-range ordering that only a few unit cells repeating, which can be observed in lowmagnification SEM image (Figure 4b). With the solvent evaporation and calcination, the arrangement of the structures can be also curved and distorted. It can also be observed in F


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Figure 5. SEM (a, b) and TEM (c, d) images of the L structure templated by PEO117-b-PS70-b-PtBA142.

opacity are consistent with the correspond TEM images. It has been derived that the formation of a new type of alternating gyroid structure is the key for the direct synthesis of i-SG, which two interwoven minority networks are occupied by the H2O-rich core with the PEO block and the THF-rich phase.62 Inverse Shifted Double-Primitive Structure (i-SDP). The intergrown structure of i-SDD and i-SDP can be synthesized by PEO117-b-PS64-b-PtBA204 and other 36 OSA polymers (see Tables S1 and S4, no. 43−79, and Figure S10) in a typical synthesis condition. As indicated by black tick marks, the SAXS pattern of the i-SDP structure (Figure 8a) exhibits a few reflections which can be indexed to 110, 200, 111, 021, 130 (310), 221, 113, 151 (511), and 242 reflections, suggesting highly ordered structures. The unit cell parameters are a = b ≈ 153 nm and c ≈ 108 nm. Besides, the i-SDD structure exists as the intergrown phase and the reflections of i-SDD are indexed by red tick marks with the unit cell parameters of a ≈ 221 nm; b = c ≈ 156 nm and the space group Ibam (No. 72). Figure 8b shows the SEM image of i-SDP and the sample consists of two sets of identical silica framework. Each silica framework contains 6-fold connectivity at their nodes and can be identified as primitive networks. The TEM images of the i-SDP structure recorded along [11̅0]SDP and [100]SDP directions are shown in Figures 8c and 8d with the corresponding FDs. Two networks shift along 0.75b and 0.25c of the original cubic lattice and the structure becomes orthorhombic with the space group Cmcm (No. 63). The structural and interconversion of the two structures have been reported in our very recent paper.27 The projections of the structural model from different directions are in accordance with the TEM images.

directions are shown in Figure 6d−f. The projections of structural model with 30% opacity agree well with the corresponding TEM images (insets of Figure 6d−f and Table S3). The two networks shift along 0.25c forming a tetragonal lattice with the space group of I41/amd, the structure of which has been studied in our previous report.12 Inverse Single-Gyroid Structure (i-SG). The i-SG structure can be synthesized by PEO117-b-PS57-b-PtBA191 and other six OSA polymers (see Tables S1 and S4, No. 31−37) in a typical synthesis condition as the minor phase distributed randomly in the bulk crystal and i-SDD structure exists as the main phase (see Figure S9). Figure 7a shows a few reflections corresponding to the i-SDD structure, the unit cell parameters of which is determined to be a ≈ 140 nm and c ≈ 198 nm. The i-SG structure with the unit cell parameter a ≈ 70 nm (determined by TEM) shows the 110 and 112 reflections overlapped with i-SDD. Figures 7b and 7c show the SEM images of i-SG structure which contains one set of gyroid networks with 3-fold connectivity at node sites. As highlighted by red arrow in [100] direction (Figures 7b and 7c), the righthanded enantiomer of i-SG structure contains left-handed screw axis centered in the void domain in the ⟨100⟩ direction. Meanwhile, the left-handed enantiomer of i-SG structure presents left-handed screw axis centered in the void domain in the ⟨111⟩ direction. Therefore, both right-handed and lefthanded enantiomers of i-SG structure can be observed as no chiral components were applied in the synthesis. The TEM images and corresponding FDs of the i-SG structure, which are taken from the [100], [110], and [111] directions, are shown in Figure 7d−f, and the structure follows the chiral space group I4132 (No. 214). The projections of structural model with 30% G


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Figure 6. SAXS pattern and SEM and TEM images of the i-SDD structure templated by PEO117-b-PS50-b-PtBA165. (a) SAXS pattern of i-SDD. (b, c) SEM images of i-SDD taken from different directions. (d−f) TEM images, corresponding FDs (insets), and structural model (insets) of i-SDD taken from [111]SDD, [010]SDD, and [101]SDD directions, respectively.

Inverse 2D Hexagonal Structure (i-H). The calcined i-H structures were templated by PEO117-b-PS105-b-PtBA167 and other 19 OSA polymers (see Table S1, no. 80−99, and Figure S11). The SAXS pattern in Figure 9a presents a board peak, suggesting a disordered structure. Figure 9b−d shows that the sample composed of tubes that are uniform in morphology: the whole tubes are open-ended and have smooth outer surfaces throughout their length. The inner silica tube surfaces are also smooth, and the circular cross section is of constant diameter along each individual tube. The length of the tubes ranged from several to tens of micrometers, while the average diameter was 30−50 nm and the wall thickness was around 5 nm. The TEM images also reveal the tube type structure with the diameter of ∼40 nm. Inverse Micellar Structure (i-M). Figure 10 shows the SEM and TEM images of calcined i-M structure templated by PEO117-b-PS105-b-PtBA308 and other eight OSA polymers (see Table S1, no. 100−108, and Figure S12). Figure 10a reveals the silica spheres with different size in a wide range of 200−800 nm. The silica spheres were hollow with a silica wall thickness of ∼50 nm measured by TEM (Figure 10b). The unit cell parameters of samples are summarized in Table S4 and Figure S13. The unit cell parameters of the samples with same structure distributed in a certain range depending on the polymer and the solvent. In the synthesis, the hydrophobic blocks A and S are present in THF-rich phases and the PEO is in the H2O-rich phase with the polymerization of silica species. The unit cell parameter of the materials is not only determined

by the polymerization degree of the polymer but also greatly affected by the solvent and the kinetic evaporation process. Therefore, it is still difficult to precise controlling the length scale of the structures at the current stage. Figure S14 shows N2 adsorption/desorption isotherms of four typical samples with nC, n-H, i-SDD, and i-H structures. Because of the hierarchical structures, complex isotherms have been observed, which contains many steps of the adsorption and desorption curves according to the hierarchical porous system. The large macroporous space and the stacking of the particles lead to the sharp increase in the high relative pressure region when the P/P0 close to 1. The BET surface area and pore volume data are shown in Table S6. However, it is very difficult to judge the precise porous structures by the isotherms due to the oversize of porous system and the complex hierarchical structures. Structural Conversion/Transition in OSA Polymers Templated Macroporous Silica. In the present system, as the solubility parameter of the PtBA block (δ = 18.5 [J/ cm3]1/2) is close to that of PS (δ = 19.3 [J/cm3]1/2) and χOA is much larger than χOS and χSA, the PtBA and PS blocks can be combined as one hydrophobic block. Given that the length of the hydrophilic PEO chains, the content of TEOS, and the nature of the solvent in the synthesis systems are identical, the variation of the length (volume fraction) of the hydrophobic blocks A and S plays a major role in the structural transition of the obtained materials (Scheme 1). In the THF−H2O solvent, the hydrophobic A and S blocks aggregate into the hydrophobic section of the assemblies, while the hydrophilic PEO chains H


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Figure 7. SAXS pattern and SEM and TEM images of the i-SG structure templated by PEO117-b-PS57-b-PtBA191. (a) SAXS pattern of the calcined material with i-SG (red tick marks) and i-SDD (black tick marks) structures. (b, c) SEM images of i-SG domains distributed in i-SDD silica taken from near [100] and [111] directions. The red arrow indicates the left-handed screw axis. (d−f) TEM images and corresponding FDs (insets) of iSG structure taken from the [100], [110], and [111] directions, respectively. The structural model is overlaid on the TEM images.

surrounded by a hydrophobic A+S+THF-rich core (oil). Through evaporation of THF and H2O, the macroporous space of structures were directed by hydrophobic segment and THF and the pores were generated by water-rich core accompanied by aggregation of silicate in hydrophilic segment. Subsequently, inverse structures, including i-SDD and i-SDP structures (lost the mutual support and could not maintain the original cubic symmetry) and randomly packed i-H and i-M structures, were produced by removing OSA polymers via calcination. The transition sequence is parallel to that observed for lipid self-assembly with an increase in p as well as that occurs in the self-assembly of diblock copolymers in bulk with the change of volume fraction of a block. In the structural transition with increasing fA+S, different structures coexist in some cases, leading to the overlaps of some phase regions. This phenomenon is often observed in BCP self-assembly,63 which can be attributed to the possibility of crossing thermodynamic stability boundaries,64 similar free energy65 for various morphologies, or the effect of polydispersity in the block lengths of the copolymers.66 The cross-linking of TEOS in the PEO phases of these structures and the subsequent removal of the copolymer templates result in the formation of the corresponding ordered silica materials. As the inverse-phase structures are formed with a water-in-oil configuration, dispersed i-H and i-M particles can be formed by the evaporation of solvent.

construct the coronae surround the hydrophobic section. When fA+S ranged from 78.5% to 84.7%, at which p is relatively small, the triblocks prefer to aggregate into spherical or cylindrical micelles with a hydrophobic A+S+THF-rich core (oil) and a PEO+H2O-rich corona (water) surround the core. This way affords the system the lowest interfacial area and increased configurational entropy relative to other morphologies and thus is energetically favorable. Meanwhile, the TEOS would be hydrolyzed and condensed in the PEO domain via hydrogen bonding. The evaporation of the solvent results in the close-packing of the spherical or cylindrical micelles with the PEO-TEOS domain connected. The cross-linking of silica species and the subsequent removal of the copolymer template give rise to the normal structures (nC and n-H). As the long-range orientationally ordering are formed by maximizing the interaction energy and minimizing the excluded volume, the cubic close packing and hexagonal close packing structures with the highest packing density are preferred by the n-C structure and the 2D hexagonal arrangement is formed by the n-H structure. The increase of the length of A+S blocks causes an increase in v/lc, and consequently the p value also increases, leading to the morphological transition from closely-packed spherical micelles to hexagonally packed cylindrical micelles and to lamellae (p = 1). With p > 1, the i-HS structures (i-SDD, i-SG, and i-SDP), inverse cylindrical micelles, and inverse spherical micelles can be formed, in which a PEO+H2O-rich corona (water) is I


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Figure 8. SAXS pattern and SEM and TEM images of the i-SDP structure templated by PEO117-b-PS64-b-PtBA204. (a) SAXS pattern of the calcined material with i-SDP (black tick marks) and i-SDD (red tick marks) structures. (b) SEM image of i-SDP structure. (c, d) TEM images and corresponding FDs (insets) and structural model (insets) of i-SDP structure taken from [11̅0]SDP and [100]SDP directions, respectively.

polymer could be the key factors to synthesize enormous interesting structures straightforwardly. Meanwhile, the 6-fold node of i-SDP structure can be pulled apart into two 4-fold nodes of i-SDD structure with the formation of a new channel between them. The relationship of the P, D, and G surfaces have been studied theoretically and experimentally in the previous publications. These three surfaces have the same genus 3 and can be interconverted by the Bonnet transformation.67,68 Sadoc and Charvolin69 proposed that these structures can be continuous deformed from G to D and further to P based on “pulling apart” or “merging” the nodes of the labyrinths. A continuous transformation containing all intermediate minimal surfaces between the P, D, and G surfaces exist as rPD, tD, tP, tG, and rG, which were reported by Fogden and Hyde70 and Schröder-Turk et al.71,72 In the copolymeric systems, simulations were calculated from the viewpoints of free energy changes. In the pure diblock copolymer melt system, the G is the only stable phase under the self-consistent field theory (SCFT).73,74 In AB diblock/A homopolymer blends system, the P and D are predicted to exist in a narrow region of the phase diagrams by tuning the composition or conformational asymmetry of the diblock copolymer chain and the length or architecture of the homopolymer. The P and D phases stabilized due to alleviating the packing frustration.75,76 Particle-based molecular simulations demonstrated that the P and the D phases as well as the G and D phases have free energies very close to each other in the

In the synthesis−field diagram of purely copolymeric system, the bicontinuous structures were observed in a very narrow range of the experimental parameters.63 However, in the present unique OSA polymer system, by combination of the solvent and inorganic source through EISA process, the microphase separation behavior has been greatly changed. Unique structures i-SDD, i-SDP, and i-SG were produced in our system derived from 108 OSA polymers, and the points of each structure were plotted in the two-component synthesis− field phase diagram mapped previously. In the two-component diagram, when the range of hydrophobic segment was in 84.1− 89.5% and relative χN ranging from 81.7 to 111.8, i-SDD structure was synthesized and the other i-HS structures intergrowth in the region of i-SDD, in which i-SG dispersed in a smaller range of fA+S and χN in contrast to i-SDP. In the three-component diagram, when the VFR of A/O in polymers is in the range of 4.2−7.1, all i-HS points were mapped out, and when the VFR of S/A were in the ranges 0.1−0.2 and 0.3−0.4, i-SDP and i-SG were produced, respectively, but both of the structures intergrown in the region of i-SDD. In this synthesis system, i-SG structure exists as the minor phase in i-SDD domains, and both structures are interconnected. Meanwhile, H2O-rich core with block O and hydrophobic block A and S dispersed in THF-rich structure form the two chemically interpenetrating gyroid networks. Because of the occupancy of space by the hydrophobic segment and solvent instead of A and C of ABC triblocks to form the alternating SG structure, the addition of solvent and the chemistry composition of OSA J


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Figure 9. SAXS pattern and SEM and TEM images of the inverse 2D hexagonal (i-H) structure templated by PEO117-b-PS105-b-PtBA167. (a) SAXS pattern of i-H structure. (b, c) SEM images of i-H taken in low magnification. (d, e) TEM images of i-H structure taken from side view.

Figure 10. SEM (a) and TEM (b) images of the inverse micelle (i-M) structure templated by PEO117-b-PS105-b-PtBA308.

and S/A changing trend diagram were prepared. Figure 11 shows three diagrams in regard to the structural changes with the variation of VFR values of S/O, A/O, and S/A versus the volume fraction of the hydrophobic blocks (fA+S). By increasing fA+S, the variation law of eight structures has been summarized. First, as shown in Figure 11a, five structures, namely, n-C, n-H, L, i-H, and i-M, have emerged by increasing of VFR value of S/ O, indicating the general variation trend of these structures. It is interesting to note that the i-SDD, i-SDP, and i-SG are not located on the curve, and the i-SDP and i-SG can be separated by changing f S, indicating that the formation of i-SDP and i-SG is predominantly affected by f S. Furthermore, in the similar fA+S region, with decreasing the VFR of S/O, the structures were

identified conditions. For one set of conditions (volume fraction of the added homopolymer = 0.325, relative degree of polymerization of the homopolymer = 0.667) all D, G, and P phases were found to have comparable free energies.77 In our system, these experimental results highly related to the previous theoretical transformations, i.e., tetragonal pathway and rPD family.67−69 However, as a huge number of parameters and the complicated conditions, there existed rare works to simulate the self-assembly of triblock copolymer in solution, let alone coassemble with inorganic species. Further investigations are under way. In order to understand the rule of O, S, and A blocks on the formation of various mesostructures, the VFRs of S/O, A/O, K


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Scheme 1. Schematic Representation of Formation of Eight Different Structures, Including n-C, n-H, L, i-HS, i-H, and i-Ma

The “polymer” list shows the template OSA polymers in the EISA system by adding of selective solvents THF and H2O and inorganic source TEOS. The “self-assembly” list shows different structures were synthesized by using OSA polymers with different volume fraction of hydrophobic block A and S from up to down increasing step by step. The “after evaporation” list indicates the formation of eight structures by evaporation of solvents and mechanism of four cross-sectional descriptions of different structures.

a

formed in the order of i-SDP to i-SDD and to i-SG. Second, as shown in Figure 11b, with increasing the VFR of A/O, structures transformed in a sequence from n-C, to n-H, to L, to i-H and i-M without involving the i-SDD, i-SDP, and i-SG structures. It is found that the i-H, i-SDD, i-SDP, and i-SG are almost in the same A/O region (can hardly be separated with each other), indicating that the effect of A volume fraction is much weaker than S for these structures. Third, as shown in Figure 11c, these structures were obtained along with the nonlinear relationship with the VFR ratio of S/A value. This nonlinear relationship can be explained by the fact that the microphase segregation of block S and A is not obvious and the different positions in Figure 2. However, it is noteworthy that with decreasing the VFR of S/A in the similar fA+S region, the iHS can be separated from other structures. At present, it is still unclear the exact impact of PtBA on the self-assembly of the terpolymer as there are too many parameters needing considerations and the synthesis system is very complicated.

We speculate that the difference between the density and volume of the PtBA and PS blocks may cause slight changes of the interfacial curvature in the bicontinuous structures, leading to the formation of i-SDD, i-SDP, and i-SG at different volume ratios of S/A. In summary, the formations of inverse-phase structures such as i-H, i-SDD, i-SDP, and i-SG were dependent on the S/O and S/A ratios. It can be considered that although the microphase segregation of block S and A is not obvious, the PS chain is more rigid than PtBA due to the existence of benzene groups in PS block. This results in a relatively higher glass transition temperature of PS block (PEO: −53 °C, PS: 100 °C, PtBA: 35 °C),78−81 which stabilizes the assemblies formed by the OSA terpolymers and inorganic species in our system.

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CONCLUSIONS We have investigated the synthesis system of macroporous silica obtained from the amphiphilic triblock terpolymer L


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Figure 11. Variation of VFRs of block S/O (a), O/A (b), and S/A (c) in different structures.

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PEO117-b-PSn-b-PtBAm as the template, a mixture of THF and water H2O as selective solvent, and TEOS as inorganic species through the EISA method. A systematic analysis of the relationship of different VFRs and interactions parameters between hydrophobic and hydrophilic blocks in 108 OSA polymers reveals the complicated structural behavior in the triblock terpolymers self-assembly in solution. Results were constituted of two synthesis−field diagrams including specific regions for various structures. This is particularly relevant for 3D photonic crystals applications where polymers control the desired structural formation and solvents may play an important role for enhancement the length scale of macroporous materials. This report may also lead to a deeper understanding of the structure behavior of ABC triblock copolymer self-assembled with inorganic species in solution, the formation, and structural transitions of hyperbolic-surface structures and provides a feasible and guiding approach to the fabrication of new porous materials.

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (L.H.). *E-mail: [email protected]; [email protected](S.C.). ORCID

Yiyong Mai: 0000-0002-6373-2597 Lu Han: 0000-0002-6119-4895 Shunai Che: 0000-0001-7831-1552 Author Contributions

X.C. and W.M. contributed equally. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (21471099, 21533002, 21571128, 51573091), the National Key R&D Program of China (2016YFC0205900), the National Excellent Doctoral Dissertation of PR China (201454), Shanghai Rising-Star Program (17QA1401700), Program of the Shanghai Committee of Science and Technology (17JC1403200), and Shanghai Natural Science Foundation (18ZR1442400).

ASSOCIATED CONTENT

S Supporting Information *

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The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.macromol.8b00242.

ABBREVIATIONS XRD, X-ray diffraction; SAXS, small-angle X-ray scattering; SEM, scanning electron microscopy; TEM, transmission electron microscopy; n-C, normal cage-type; n-H, normal 2D

Experiment details, supporting figures (PDF) M


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hexagonal; L, lamellae; i-HS, inverse hyperbolic-surface; i-SG, inverse single-gyroid; i-SDP, inverse shifted double-primitive; iSDD, inverse shifted double-diamond; i-H, inverse 2D hexagonal; i-M, inverse micelle; FD, Fourier diffractogram.

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