Synthesis and Characterization of Poly(iminofuran-arylene

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Synthesis and Characterization of Poly(iminofuran-arylene) Containing Bromomethyl Groups Linked at the 5‑Position of a Furan Ring via the Multicomponent Polymerizations of Diisocyanides, Dialkylacetylene Dicarboxylates, and Bis(2-bromoacetyl)biphenyl Weiqiang Fu,† Jianbing Shi,*,† Bin Tong,† Zhengxu Cai,† Junge Zhi,‡ and Yuping Dong*,† Macromolecules Downloaded from pubs.acs.org by UNIV OF LOUISIANA AT LAFAYETTE on 04/23/19. For personal use only.

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Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, School of Materials Science and Engineering and ‡Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China S Supporting Information *

ABSTRACT: A catalyst-free multicomponent polymerization (MCP) was developed for the in situ construction of iminofuran-arylene-containing polymers (PIFAs) with high molecular weights (Mw up to 24 300) and high yields (up to 89.7%). The structure of the PIFAs was characterized by gel permeation chromatography, Fourier transform infrared, and NMR. The thermal and photophysical properties of the PIFAs were also investigated. The results indicated that the PIFAs have good solubilities and thin-film processibility. Moreover, most of the obtained PIFAs have high refractive indices of visible light (400−800 nm) because of the existence of bromide, nitrogen, and oxygen atoms in each repeating unit. Some of the PIFAs showed aggregation-enhanced emission behavior and could be good candidates for bioimaging or therapy of specific cells. Because of the bromomethyl groups on the 5-position of the furan in the side chain, the PIFAs are better macromolecular catalysts for living polymerizations that result in star-branched or brush polymers. Thus, this MCP provides a new kind of multifunctional material by modifying the different monomer structures and/or side chains.

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INTRODUCTION The development of new polymerization reactions is of academic interest and technological value. In recent years, multicomponent polymerization (MCP) has become a powerful strategy for synthesizing complex and useful polymeric structures by using three or more commercially available or easily prepared reactants. 1 To date, polyester,2 poly(enaminone),3 polymacrocycles,4 poly(arylene thiophenylene),5 poly(N-sulfonylamidines),6 poly(ester-amide),7 and πconjugated pyrrole-based polymers8 have been synthesized by MCPs due to the ease of monomer preparation, high efficiency, controllable polymer structure, mild reaction conditions, and high atom economy. The development of new MCPs is dependent on the development of the multicomponent coupling reactions (MCRs) of small molecules. There are a large number of extensively studied MCRs with well-defined sequence structures, such as Passerini,9 Ugi,10 Biginelli Mannich,11 Hantzsch reaction,12 and A3coupling reactions,13 which have been used in the exploration of polymer synthesis.14 More importantly, Meier’s group synthesized sequence-defined and information-coding macromolecules through multicomponent reactions; these macromolecules are suitable as data-storage materials.15 Isocyanides and alkynes are recognized as useful triple-bond monomer building blocks in polymer chemistry. In 2017, Tang © XXXX American Chemical Society

reported a new MCP approach that enabled the synthesis of functional poly(propargyl imine)s with Pd-catalyzed dibromoarenes, isonitriles, and diynes.16 In particular, the development of metal-free catalyzed triple-bond polymerization has received more attention due to its alignment with green chemistry.17 Additionally, polymers without metal-catalyst residues are easy to postfunctionalize due to the decreased toxicity of the potential applications. Our group has recently investigated the development of new polymerizations based on triple-bond monomers,18−21 in which cyclo/spiro units were formed in situ during the polymerization process. Moreover, we synthesized a series of high-molecular-weight poly(aminefuran-arylene)s by catalyst-free cyclopolymerization of diisocyanide, dialkylacetylene dicarboxylates (DAAD), and dialdehyde under mild experimental conditions.22 These modified polyfurans have shown good thermal stabilities and filmprocessing properties. Iminolactones (also named iminofurans) are also an important class of heterocyclic compounds due to their potential biological properties and use in biological fields, such as in aldosterone inhibitors,23 antibacterial agents,24 and precursors for the preparation of a wide spectrum Received: February 27, 2019 Revised: April 7, 2019

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DOI: 10.1021/acs.macromol.9b00408 Macromolecules XXXX, XXX, XXX−XXX

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Macromolecules Scheme 1. Proposed MCPs of Diisocyanides, DAADs, and Bis(2-bromoacetyl)biphenyl

of natural compounds.25 Additionally, iminolactones can be hydrolyzed with aqueous hydrochloric acid to produce butenolides.26 In general, a defined iminolactone structure was synthesized by the catalyst-free one-pot MCR of isocyanide, DAAD, and acetophenone.27,28 Among these components, acetophenone must have a strong electronwithdrawing group in the benzene ring or acetyl group. However, the synthesis of iminofuran-containing polymers has not yet been reported. Moreover, aryl halides are useful groups for constructing functionalized polymers that undergo coupling reactions with living polymerizations,29,30 especially for the synthesis of star-branched polymers or polymer brushes.31,32 With the above-mentioned investigations in mind, we found that isocyanide can quickly attack an activated DAAD to provide a highly reactive zwitterionic intermediate. The zwitterionic intermediate can add to carbonyl-containing compounds, leading to a dipolar species. It is worth noting that MCP can often occur when the carbonyl group in a diketone that contains an electron-withdrawing group, such as nitro, cyano, halogen, and thiocyanate, is highly activated.26−28,33 4,4′-Bis(2-bromoacetyl)biphenyl is a commercially available diketone and provides an aryl bromide when the polymerization is accomplished. Based on our experience with MCPs, we inferred that the reaction between the zwitterionic intermediates made from diisocyanides 1a−c, DAADs 2a−b, and 4,4′-bis(2-bromoacetyl)biphenyl resulted in 3,4-carboxylates poly(iminofuran-arylene)s (PIFAs), as shown in Scheme 1, which can also contain an aryl bromide group on the 5-position of the furan ring. The zwitterionic intermediate (I) adds to the carbonyl group of the aryl bromide diketone 3, which leads to the iminofuran-arylene structural unit (intermediate II).34 Intermediate II contains a dipolar group on one end and a 2-bromo-acetophenone group on other end. The reaction is then repeated from intermediate II under the same process. Eventually, 3,4-carboxylates iminofuran-arylene-based polymers are formed (PIFAs), which contain two bromomethyl groups in every repeat unit. To the best of our knowledge, reports on the use of aryl bromide diketone as a monomer in a catalyst-free cyclopolymerization to construct rich bromomethyl-modified polyfurans are rare. These compounds may be precursors to developing functionalized star-branched polymers or polymer

brushes. Moreover, the rich carboxylate groups in the side chain of the PIFAs can be easily modified or chemically linked to other groups to form multifunctional PIFAs, which could provide a new kind of advanced polymeric material.

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RESULTS AND DISCUSSION Polymerization. The diisocyanide monomers 1a−c were prepared according to our previous work.22 DAAD monomers 2a−b and diketone monomer 3 are commercially available chemicals and were used directly without purification. First, we used 1a, 2b, and 3 to investigate the polymerization conditions. According to the mechanism of polymerization, the optimal ratio of 1a to 2b is 1:2. Then, we attempted to determine the optimal ratio of 1a to 3, beginning with the same ratio of 1a to 2b. The data collected are shown in entries 1−3 of Table S1. The weight-average molecular weights (Mw) of the PIFAs increased with the increasing concentration of 3 from 0.04 to 0.08 M. When the ratio of 1a to 3a was 1:1, the yield of the PIFAs slightly decreased (Table S1, entry 3). This result is probably due to the enhanced viscosity of the polymerization system with the increasing concentration of 3, which results in an increased efficiency of the effective collisions between the monomers but a reduced diffusion rate of monomers, leading to a higher Mw and lower yield. When the concentration of 1a and 3 were increased, a gel was generated in moderate yield (Table S1, entry 4), which agreed with the above inference. However, if the concentration of both 1a and 3 was decreased, a smaller Mw and a lower yield were obtained, as shown in entry 5 of Table S1. Considering the Mw and yield, 0.08 M of 1a and 0.06 M of 3 were chosen for the next MCPs. Second, the effect of solvent on polymerization was investigated (Table 1). The MCP proceeded well in toluene to produce PIFAs with good Mw, yields, and solubilities (Table 1, entry 1). However, if the MCP was carried out in other solvents such as 1,2-dichloroethane (DCE) and 1,4-dioxane, lower Mw polymers were generated in moderate yields (Table 1, entries 2 and 3). The MCP did not occur in dimethyl sulfoxide (DMSO), as shown in entry 4 of Table 1. It is speculated that the lower-polarity solvents are beneficial to this MCP under optimized monomer ratios of 1a, 2b, and 3. B

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Macromolecules Table 1. Effect of Solvent on the MCPsa entry

solvent

yield (%)

Mwb

Đ

solubilityc

1 2 3 4

toluene DCE 1,4-dioxane DMSO

80.5 72.9 64.2

20 400 8000 6100

1.92 1.90 1.65

◯ ◯ ◯

indicated that these PIFAs could easily be postfunctionalized in deed, as shown in Figures S1−S4. For an example, the bromide group could be transformed into the azide group and then clicked with the alkynyl group (transformation degree is up to 98%), which can expand a large scope of multifunctional materials. Structural Characterization. To assist in the structural analysis of the PIFAs, a model compound MC was prepared by the reaction of 1a and 2b with 2-bromoacetophenone 4, as shown in Scheme 2. To confirm the polymers’ structure, all PIFAs were characterized by Fourier transform infrared (FTIR) and NMR spectroscopy. Taking P1a2b3 as an example, the FT-IR spectra of P1a2b3 as well as MC, 1a, 2b, and 3 are shown in Figure 1. The absorption peak of 1a associated with

d

Carried out under air at 100 °C for 6 h, [1a] = 0.08 M, 1a:2b = 1:2, [3] = 0.06 M. bDetermined by GPC in THF on the basis of a linear polystyrene as the calibration standard. Mw = weight-average molecular weight; Đ = Mw/Mn, where Mn = number-average molecular weight. c◯ = completely soluble in DCM, THF, and CHCl3. dNo polymerization. a

Next, we investigated the time course of the MCPs (Table S2). The MCPs were carried out for 6 h and produced PIFAs with good Mw and yields (Table S2, entry 2). There were no obvious increases in the Mw and yields, even when the polymerization time was prolonged to 9 h. However, the polydispersion index increased (Table S2, entry 3) under prolonged reaction time. Therefore, we chose 6 h as the preferable polymerization time. Then, the effect of temperature on the MCP was investigated (Table S3). The yields and Mw were increased when the polymerization temperature was increased from 60 to 100 °C (Table S3, entries 1−3). The increase in the Mw observed for this MCP indicated that the polymerization was temperature-dependent because both the reactivity and the diffusion rates were improved at higher temperature. Finally, we extended the monomer scope of this MCP, and different combinations of monomers were tested under the optimized polymerization conditions (Table 2). The MCPs

Figure 1. FT-IR spectra of (A) 1a, (B) 2b, (C) 3, (D) MC, and (E) P1a2b3.

Table 2. Polymerization Data of Different Monomer Combinationsa entry

PIFAs

monomers

yield (%)

Mw

Đ

solubility

1 2 3 4 5 6

P1a2a3 P1a2b3 P1b2a3 P1b2b3 P1c2a3 P1c2b3

1a+2a+3 1a+2b+3 1b+2a+3 1b+2b+3 1c+2a+3 1c+2b+3

83.2 80.5 76.4 74.8 89.7 87.2

12 000 20 400 21 800 24 300 17 600 12 100

2.50 1.92 2.53 2.17 2.63 1.98

◯ ◯ ◯ ◯ ◯ ◯

the NC stretching vibration was observed at 2135 cm−1 (Figure 1A), which disappeared in the spectra of MC and P1a2b3 (Figure 1D,E, respectively). The CO stretching vibration observed at 1723 cm−1 in 2b (Figure 1B) was divided into two peaks at 1680 and 1721 cm−1 in the spectra of MC and P1a2b3, respectively, after the formation of the iminolactone due to the different chemical environments of the two types of carbonyl groups in MC and P1a2b3.35 The absorption peak of MC associated with the CN stretching vibration was observed at 1654 cm−1. However, it was invisible in the spectrum of P1a2b3 due to the signal of CO covering the stretching vibration of CN in the polymer. A new peak at 1093 cm−1 in the spectra of MC and P1a2b3 was attributed to the C−O stretching vibration. The FT-IR spectra of the other PIFAs showed similar results (Figures S5−S9 in the Supporting Information). All the structural results indicated that the MCPs proceeded to the target materials in the optimized experimental conditions. More structural information about the PIFAs was obtained from NMR spectroscopy. The 1H and 13C NMR spectra of 1a, 2b, 4, MC, and P1a2b3 are shown in Figures 2 and 3, respectively. Monomer 3 is poorly soluble in CDCl3 at room

a Carried out in toluene under air at 100 °C for 6 h; [1] = 0.08 M, 1a:2b = 1:2, [3] = 0.06 M.

proceeded smoothly to provide PIFAs in satisfactory yields (up to 89.7%) and Mws (up to 24 300), whether the diisocyanides 1a−c were aliphatic or aromatic compounds. All obtained PIFAs had good solubilities in common organic solvents, such as dichloromethane (DCM), tetrahydrofuran (THF), CHCl3, etc. These results indicated that the MCP had good monomer universality of diisocyanides and could produce various multifunctional materials through the adjustment of the monomer spacer. Moreover, the postfunctionalization of P1a2b3 as an example was investigated, and the results Scheme 2. Synthetic Route to Model Compound MC

C

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temperature and would deteriorate under heating; thus, we selected compound 4 for the NMR reference because 4 has the same functional group as compound 3. The peak at δ 3.80 ppm, which was assigned to the resonance of Ha in 1a, shifted to 3.76 and 3.79 ppm in MC and P1a2b3, respectively, as shown in Figure 2. The resonances of Hb, Hc, and Hd in 2 and 4 split into two independent peaks due to the resonances of Hb1′ and Hb2′, Hb1″ and Hb2″, Hc1′ and Hc2′, Hc1″ and Hc2″, Hd1′ and Hd2′, Hd1″ and Hd2″ in MC and P1a2b3, respectively, which are due to their different chemical environments in the iminolactone units. The peak at δ 7.95 ppm that was assigned to the resonance of He in 4 disappeared at MC and P1a2b3, which indicated that the ketone group was completely consumed during the polymerization. In addition, further structural clarity of P1a2b3 was confirmed by the 13C NMR spectra of 1a, 2b, 4, MC, and P1a2b3, as shown in Figure 3. The resonance of Ca in 1a at δ 156.91 ppm, Cb in 2b at δ 77.36 ppm, and Cd in 4 at δ 191.29 ppm completely disappeared in the spectra of MC and P1a2b3. The peak at δ 151.81 ppm assigned to the resonance of Cc in 2b was split into two peaks centered at δ 160.74 and 161.73 ppm and at 160.75 and 161.72 ppm in MC and P1a2b3, respectively. The peak at δ 31.12 ppm, which was assigned to the resonance of Ce in 4, changed to 36.90 and 36.79 ppm in MC and P1a2b3, respectively. Moreover, the two new peaks that appeared at δ 90.01 and 154.80 ppm were assigned to the resonances of Cf and Cg in MC, and the peaks at 89.89 and 154.72 ppm were assigned to the resonances of Cf′ and Cg′ in P1a2b3. These results suggested that iminofuran rings were formed after the reaction. The 1H NMR and 13C NMR spectra of the other PIFAs obtained showed similar results (Figures S10−S19 in the Supporting Information). Considering the above FT-IR and NMR results, the MCPs proceed quickly for the preparation of PIFAs. Thermal Stability. The thermal stabilities of PIFAs were evaluated by thermogravimetric analysis. The onset of the degradation temperature (Td, 5% loss of their weight under N2) ranged from 162 to 195 °C due to the existence of the bromomethyl groups in the PIFAs (Figure 4). The bromine fraction of the PIFAs ranged from 15 to 19% according to one structural unit calculation, which corresponded well with the mass loss of the PIFAs at about 200 °C. The abrupt weight loss

Figure 2. 1H NMR spectra of (A) 1a, (B) 2b, (C) 4, (D) MC, and (E) P1a2b3 in CDCl3. The solvent peaks are marked with asterisks.

Figure 3. 13C NMR spectra of (A) 1a, (B) 2b, (C) 4, (D) MC, and (E) P1a2b3 in CDCl3. The solvent peaks are marked with asterisks.

Figure 4. Thermograms of (A) P1a2a3, P1b2a3, and P1c2a3 and (B) P1a2b3, P1b2b3, and P1c2b3 measured under N2 at a heating rate of 10 °C/min. D

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Macromolecules of P1a2b3, P1b2b3, and P1c2b3 at 188, 153, and 179 °C probably resulted from the relative more free volume among these molecular stacking because of ethyl groups. Both P1c2a3 and P1c2b3 showed higher carbon residues mainly due to the aromatic structure of 1c, which forms a more stable backbone in PIFAs.21 Light Refractivity. Polymeric materials containing heteroatoms usually show a high refractive index (RI).36 The obtained PIFAs contained bromine, nitrogen, and oxygen elements in every repeat unit. Therefore, these PIFAs should have a higher RI. Moreover, PIFAs can easily form polymer films due to their good solubility in common organic solvents. Therefore, the RI values of both P1a2b3 and P1c2a3 in the spectral region of 400−900 nm were measured (Figure 5). The

PIFAs could potentially provide a kind of high RI material through MCPs. Photophysical Properties. As shown in Scheme 1, the backbone of the PIFAs has a conjugated repeat unit through the in situ formation of the iminofuran parts. Therefore, the UV absorption and photoluminescence (PL) spectra of MC, P1a2b3, P1b2b3, and P1c2b3 in THF were recorded and normalized for easy comparison, as shown in Figure 6. There was one main peak centered around 270 nm, which attributed to the π−π* transition of biphenyl group. Among these polymers, P1c2b3 had a weak UV absorption in the longer wavelength due to the increased conjugation caused by more benzene rings in the main chain, as shown in the inserted part of Figure 6A. There was no emission in dilute THF solution (10 μM) of all these PIFAs. However, weak emission can be observed with increasing concentration up to 1 mM, and their normalized PL spectra of MC, P1a2b3, P1b2b3, and P1c2b3 in THF are shown in Figure 6B. MC exhibited an emission peak centered at 367 nm, whereas those of P1a2b3, P1b2b3, and P1c2b3 red-shifted to 543, 518, and 528 nm, respectively, due to their biphenyl structural units and higher rigidity and coplanarity at high concentration conditions. Interestingly, during optimized experimental conditions, we found that the PL intensity and the maximum emission wavelength can be changed with different excitation wavelengths, as shown in Figure 7A,B, ranging from 452 to 552 nm excited at 400 nm and from 504 to 566 nm excited at 400 nm, respectively. This PL behavior may belong to typical clustering-triggered emission (CTE), which is reported by Yuan et al. in some nonconventional chromophores systems.37−39 Due to a large amount of ester groups of P1a2b3, they must be clustered together when the concentration was increased, which resulted in cluster luminescence that was similar with previous polyheterocycles decorated with multisubstituted carboxylate ester.35 It is also worth noting that the PL intensity would be decreased if the concentration of P1a2b3 was too large. This may result from the π−π stacking interaction of biphenyl at very high concentration, which was an opposite effect for the PL property of PIFAs. Further, the UV absorption spectra of P1a2b3 in THF under different concentrations were investigated and is shown in Figure 7C. With increasing concentration, the absorption peak of P1a2b3 in the longer

Figure 5. Refractive indices of thin solid films of P1a2b3 and P1c2a3.

PIFAs possessed a higher refractive index (P1a2b3: n = 1.582 at 632.8 nm; P1c2a3: n = 1.623 at 632.8 nm) than commercially important optical plastics, such as polycarbonate (n = 1.581 at 632.8 nm). P1c2a3 showed a higher RI than P1a2b3, probably due to the higher conjugation. The other refractive indices of the obtained PIFAs were also high (Figures S20 in the Supporting Information). Therefore, the

Figure 6. (A) Normalized UV absorption spectra of MC, P1a2b3, P1b2b3, and P1c2b3 in THF (10 μM). (B) Normalized PL spectra of MC, P1a2b3, P1b2b3, and P1c2b3 in THF (1.0 mM). Excitation wavelength: 280 nm for MC and 420 nm for P1a2b3, P1b2b3, and P1c2b3. E

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Figure 7. PL spectra of P1a2b3 in THF under different concentrations with different excitation wavelengths at (A) 400 nm and (B) 440 nm. (C) UV−vis absorption spectra of P1a2b3 in THF under different concentrations.

wavelength band was significantly enhanced, which was caused by the formation of clusters and agreed with other CTE systems. Luminogens with CTE property usually show aggregationinduced emission (AIE) or aggregation-enhanced emission (AEE) features. So, the AIE behaviors of P1a2b3 in the mixture of THF and H2O were investigated, and their spectra are shown in Figure 8. In general, polymers tend to cause fluorescence quenching (ACQ) in the aggregated state.40 However, P1a2b3 did not undergo ACQ in the aggregated state. Conversely, the polymer fluorescence was enhanced when the water fraction was over 60% (inset curve of Figure 8). Therefore, P1a2b3 showed a typical AEE-active behavior.41,42 As also shown in Figure S21, P1b2b3 also showed AEE characteristics. Because of weak emission of MC and P1c2b3 in the mixture of THF and H2O, no AEE behavior was observed when water fraction was increased even up to 90%. All these results indicated that the photophysical property of PIFAs could be easily adjusted by changing the chemical spacer structures of monomer 1. In addition, the PL spectra and the quantum yields of P1a2b3 and P1b2b3 in solid were also investigated and are shown in Figure S22. The full width at half-peak of P1a2b3 and P1b2b3 in solid was 108 and 109 nm, respectively, which became smaller than that of those in THF solution (135 nm for P1a2b3 and 116 nm for P1b2b3). The absolute quantum yield of P1a2b3 and P1b2b3 in solid

Figure 8. PL spectra of P1a2b3 in different water fractions of THF/ H2O mixtures (1.0 mM) at excitation wavelength of 420 nm. Inset: Variation of maximum PL intensity of P1a2b3 with the water fraction in THF/H2O.

was 6.57 and 4.52%, respectively, which was not very high even though they were AEEgens. This is probably due to the existence of bromide atom and/or weak fluorescent biphenyl units. F

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Functional Poly(arylene thiophenylene) with Aggregation-Enhanced Emission Characteristics. Macromolecules 2014, 47, 4920−4929. (6) Lee, I. H.; Kim, H.; Choi, T. L. Cu-Catalyzed Multicomponent Polymerization to Synthesize a Library of Poly(N-sulfonylamidines). J. Am. Chem. Soc. 2013, 135, 3760−3763. (7) Zhang, J.; Wu, Y.-H.; Wang, J.-C.; Du, F.-S.; Li, Z.-C. Functional Poly(ester-amide)s with Tertiary Ester Linkages via the Passerini Multicomponent Polymerization of a Dicarboxylic Acid and a Diisocyanide with Different Electron-Deficient Ketones. Macromolecules 2018, 51, 5842−5851. (8) Kayser, L. V.; Vollmer, M.; Welnhofer, M.; Krikcziokat, H.; Meerholz, K.; Arndtsen, B. A. Metal-Free, Multicomponent Synthesis of Pyrrole-Based π-Conjugated Polymers From Imines, Acid Chlorides and Alkynes. J. Am. Chem. Soc. 2016, 138, 10516−10521. (9) Llevot, A.; Boukis, A. C.; Oelmann, S.; Wetzel, K.; Meier, M. A. R. An Update on Isocyanide-Based Multicomponent Reactions in Polymer Science. Top. Curr. Chem. 2017, 375, 66. (10) Yang, B.; Zhao, Y.; Wei, Y.; Fu, C.; Tao, L. The Ugi Reaction in Polymer Chemistry: Syntheses, Applications and Perspectives. Polym. Chem. 2015, 6, 8233−8239. (11) Boukis, A. C.; Llevot, A.; Meier, M. A. High Glass Transition Temperature Renewable Polymers via Biginelli Multicomponent Polymerization. Macromol. Rapid Commun. 2016, 37, 643−649. (12) Zhang, Q.; Zhang, Y.; Zhao, Y.; Yang, B.; Fu, C.; Wei, Y.; Tao, L. Multicomponent Polymerization System Combining Hantzsch Reaction and Reversible Addition-Fragmentation Chain Transfer to Efficiently Synthesize Well-Defined Poly(1,4-dihydropyridine)s. ACS Macro Lett. 2015, 4, 128−132. (13) Chan, C. Y. K.; Tseng, N.-W.; Lam, J. W. Y.; Liu, J.; Kwok, R. T. K.; Tang, B. Z. Construction of Functional Macromolecules with Well-Defined Structures by Indium-Catalyzed Three-Component Polycoupling of Alkynes, Aldehydes, and Amines. Macromolecules 2013, 46, 3246−3256. (14) Jiang, X.; Feng, G.; Lu, G.; Huang, X. Application of Named Reactions in Polymer Synthesis. Sci. China: Chem. 2015, 58, 1695− 1709. (15) Boukis, A. C.; Meier, M. A. R. Data Storage in SequenceDefined Macromolecules via Multicomponent Reactions. Eur. Polym. J. 2018, 104, 32−38. (16) Huang, H.; Qiu, Z.; Han, T.; Kwok, R. T. K.; Lam, J. W. Y.; Tang, B. Z. Synthesis of Functional Poly(propargyl imine)s by Multicomponent Polymerizations of Bromoarenes, Isonitriles, and Alkynes. ACS Macro Lett. 2017, 6, 1352−1356. (17) Liu, Y.; Qin, A.; Tang, B. Z. Polymerizations based on triplebond building blocks. Prog. Polym. Sci. 2018, 78, 92−138. (18) Tian, Y.; Li, X.; Shi, J.; Tong, B.; Dong, Y. Monomer-Induced Switching of Stereoselectivity and Limitation of Chain Growth in the Polymerization of Amine-Containing Para-Substituted Phenylacetylenes by [Rh(norbornadiene)Cl]2. Polym. Chem. 2017, 8, 5761−5768. (19) Fu, W.; Dong, L.; Shi, J.; Tong, B.; Cai, Z.; Zhi, J.; Dong, Y. Synthesis of Polyquinolines via One-Pot Polymerization of Alkyne, Aldehyde, and Aniline under Metal-Free Catalysis and Their Properties. Macromolecules 2018, 51, 3254−3263. (20) Fu, W.; Dong, L.; Shi, J.; Tong, B.; Cai, Z.; Zhi, J.; Dong, Y. Multicomponent Spiropolymerization of dDiisocyanides, Alkynes and Carbon Dioxide for Constructing 1,6-Dioxospiro[4,4]nonane-3,8diene as Structural Units under One-Pot Catalyst-Free Conditions. Polym. Chem. 2018, 9, 5543−5550. (21) Fu, W.; Dong, L.; Shi, J.; Tong, B.; Cai, Z.; Zhi, J.; Dong, Y. Synthesis and Characterization of Poly(ethene−ketone−arylene− ketone)s Containing Pendant Methylthio Groups via Metal-Free Catalyzed Copolymerization of Aryldiynes with DMSO. Polym. Chem. 2018, 9, 4404−4412. (22) Fu, W.; Kong, L.; Shi, J.; Tong, B.; Cai, Z.; Zhi, J.; Dong, Y. Synthesis of Poly(amine−furan−arylene)s through a One-Pot Catalyst-Free in Situ Cyclopolymerization of Diisocyanide, Dialkylacetylene Dicarboxylates, and Dialdehyde. Macromolecules 2019, 52, 729−737.

CONCLUSIONS In summary, a catalyst-free one-pot MCP was developed for obtaining multifunctional PIFAs by adjusting the diisocyanides and/or the DAAD. This MCP can yield high-molecular-weight polymers with bromomethyl groups on their repeat units, and the synthesized polymers are potential candidates for macromolecular catalysts of living polymerization. The PIFAs showed good film-processing properties and high refractive indices in the visible region due to their rich heteroatom contents. Some of the PIFAs exhibited AEE characteristics and could be applied in many fields, such as bioimaging and therapy. Therefore, further postfunctionalization of the PIFAs and their related applications are ongoing in our laboratory and our collaborator’s laboratory. Overall, this MCP provides a good tool for extending multifunctional materials by catalystfree reactions.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.macromol.9b00408.

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Experimental procedures and structural characterization data; FT-IR, 1H NMR, and 13C NMR of representative polymer products (PDF)

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (J.S.). *E-mail: [email protected] (Y.D.). ORCID

Jianbing Shi: 0000-0002-4847-1472 Zhengxu Cai: 0000-0003-0239-9601 Yuping Dong: 0000-0001-7437-0678 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was financially supported by the National Natural Science Foundation of China (Grants 21490574, 21875019, 51673024, and 51803009), Graduate Technological Innovation Project of Beijing Institute of Technology (2018CX10005), and Beijing Institute of Technology Research Fund Program for Young Scholars.

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DOI: 10.1021/acs.macromol.9b00408 Macromolecules XXXX, XXX, XXX−XXX