Copolymerizations of substituted acetylenes have been intensively studied in solution polymerization for constructing chirally helical polymers, while emulsion copolymerizations of the kind of monomers have been only scarcely reported. In the present study, chiral substituted acetylene monomer containing cholic acid group underwent emulsion copolymerizations with an achiral acetylenic monomer in the presence of rhodium catalyst, providing optically active helical copolymer nanoparticles. Synergistic effects were found in the resulting helical copolymers, enabling one certain copolymer to show the maximum CD signal intensity. Moreover, the helicity of the helical copolymers in nanoparticle state was opposite to that in solution state. This is the first demonstration that synergistic effects and helicity inversion simultaneously occurred in helical copolymers prepared by emulsion copolymerization process. To deepen the understanding of the unique phenomena, corresponding solution copolymerization and emulsification process were also investigated. Different from “Sergeant and Soldiers rule” approach, the present study provides a new strategy for preparing chirally helical polymer particles by making full use of achiral monomers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1679–1685

Functional materials derived from synthetic helical polymers are attracting increasing interest. Helically substituted polyacetylenes (HSPAs) are especially interesting as typical artificial helical polymers. In recent years, we designed and prepared a series of functional materials based on HSPAs and inorganic materials. The target is to establish some novel hybrid materials that combine the superior properties of both. The examined inorganic materials include silica, graphene, and magnetic Fe₃O₄ nanoparticles. Such new functional materials hold great promise and are expected to find practical applications, for instance, as chiral absorbents, chiral sensors, chiral selectors for inducing enantioselective crystallization, chiral catalysts towards asymmetric catalysis, and chiral carriers for enantioselective release. The Personal Account summarizes our major achievements in preparing optically active hybrid materials. We hope it will speed up progress in chiral-related research areas.

This article reports a novel category of helical substituted polyacetylenes bearing pendant thiourea groups and showing remarkable asymmetric catalysis ability. Thiourea-based monomer and another chiral monomer underwent copolymerization, affording copolymers with considerable optical activity. The copolymers were used as chiral organocatalyst to homogeneously catalyze the asymmetric Michael addition of diethyl malonate to trans-β-nitrostyrene. During catalysis, a synergetic effect occurred between the pendant thiourea moieties and the helical structures in the polymer backbones. The enantioselectivity of the reaction was governed by the thiourea moieties. Meanwhile, the concaves along the helices provided specific domains where the substrates and catalytic groups were packed together, leading to a remarkable enhancement of product yield and enantioselectivity. Product with high yield (85%) and satisfactory ee (up to 72%) can be obtained. The present helical polymers open up new opportunities for developing macromolecules as mimetic enzymes catalyzing asymmetric reactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1816–1823

This Communication reports two substituted polyacetylenes that can adopt helical structures of preferential screw sense in both emulsion (nanoparticle) and solution; however, the handedness of the macromolecular helices is just opposite in the two states. More interestingly, the helical screw sense of the polymers demonstrated a reversible transition between the two states. The unprecedented findings are of significant importance for acquiring new insights into helical polymers and for developing novel advanced chiral materials.

This communication reports the first integration of two significant concepts, “macromolecular helicity-derived chirality,” and “magneticity” in one single microsphere entity. The novel chiral magnetic composite microspheres consisted of magnetic Fe₃O₄ nanoparticles and optically active helical substituted polyacetylene. Therefore, they exhibited both remarkable optical activity and magneticity. The microspheres adsorbed (R)-(+)-1-phenylethylamine much more quickly than the other enantiomer, demonstrating the potential applications of the chiral magnetic composite microspheres in chiral recognition and chiral resolution.

This Communication reports optically active helical substituted polyacetylenes which solely catalyzed asymmetric Aldol reaction between cyclohexanone and p-nitrobenzaldehyde; more importantly the helical structures are found to play crucial roles in the asymmetric catalysis, with a remarkable yield and ee (both up to 80%). A synergic effect is observed between the helical structures in the polymer main chains and the pendent prolinamide moieties for successfully catalyzing the asymmetric reaction. The role of the helical polymer backbones is further verified by tuning the relative helical structure content.

A novel type of polymeric beads with high oil absorbency was prepared via suspension polymerization technique. For this purpose, β-cyclodextrin with vinyl groups (β-CD-MA) was first synthesized from β-cyclodextrin (β-CD) and glycidyl methacrylate, and identified by FT-IR and ¹H-NMR spectroscopy analyses. Suspension polymerizations were carried out with styrene and stearyl acrylate as co-monomers, β-CD-MA as cross-linking agent, poly(vinylalcohol) as stabilizer and azoisobutyronitrile as initiator, providing polymeric beads in a quantitative yield. The oil-absorbent beads had a porous structure and exhibited high oil absorbency: 55 times the dry weight in toluene, 52 times in xylene, 75 times in CHCl₃ and 102 times in CCl₄. The novel beads also showed high absorbency toward toluene from a toluene/water mixture, demonstrating the potential applications of such novel oil-absorbent beads for cleaning organic contaminations from water. Copyright © 2011 John Wiley & Sons, Ltd.

A series of optically active nanoparticles composed of helical substituted polyacetylene is prepared via emulsion polymerization. A specific organic solvent is required for solid substituted acetylene monomers to undergo emulsion polymerization. The effects of this organic solvent are investigated. Its amount is found to be decisive for obtaining stable polymer emulsions. The helical conformations of the substituted polyacetylenes in nanoparticle state are identified with the help of CD and UV-vis spectra. A blue shift occurs in CD and UV-vis spectra of some of the polyacetylene emulsions. The underlying driving force for the blue shift is discussed, and an emulsion polymerization mechanism is proposed.

This article reports on optically active core/shell nanoparticles constituted by chiral helical polymers and prepared by a novel approach: using self-assembled polymer micelles as reactive nanoreactors. Such core/shell nanoparticles were composed of optically active helical-substituted polyacetylene as the core and thermosensitive poly(N-isopropylacrylamide) as the shell. The synthetic procedure is divided into three major steps: (1) synthesis of amphiphilic diblock copolymer bearing polymerizable C[tbond]C bonds via atom transfer radical polymerization, followed by (2) self-assembly of the diblock copolymer to form polymer micelles; and (3) catalytic emulsion polymerization of substituted acetylene monomer conducted using the polymer micelles as reactive nanoreactors leading to the core/shell nanoparticles. The core/shell nanoparticles simultaneously exhibited remarkable optical activity and thermosensitivity. The facile, versatile synthesis methodology opens new approach toward preparing novel multifunctional core/shell nanoparticles.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

This article reports for the first time a novel category of hollow organic@inorganic hybrid two-layered nanoparticles (NPs), in which the inner layer is formed by optically active helical polyacetylene, and the outer layer by silica. Such NPs show remarkable optical activity and are successfully used for enantioselective crystallization. To prepare such NPs, n-butyl acrylate undergoes radical polymerization to first form poly(n-butyl acrylate) (PBA) cores two shells by catalytic polymerization of substituted acetylene and sol–gel approach of TEOS (tetraethyl orthosilicate), respectively. Removal of the PBA cores provides the expected hollow core/shell NPs. The intense dircular dichroism (CD) effects demonstrate that the hollow chiral NPs possess considerable optical activity, arising from the helical substituted polyacetylenes forming the inner layer. The hollow NPs are further used as chiral templates to induce enantioselective crystallization of racemic alanines, demonstrating the significant potential applications of the hollow chiral NPs in chiral technologies. Also of particular significance is the detailed process of the induced crystallization observed by TEM. The strategy for preparing the hollow hybrid chiral NPs should be highlighted since it combines free radical polymerization and catalytic polymerization with sol–gel process in a single system, by which numerous advanced materials will be accessible.

Cross-linked microspheres consisting of optically active helical substituted polyacetylenes are reported. For preparing the microspheres, substituted polyacetylene copolymers with pendent polymerizable CC bonds are first prepared and then used as macromonomers to copolymerize with acrylates via suspension polymerization, providing cross-linked microspheres. The helical polymer segments render the microspheres with optical activity, whereas the acrylate-based polymers afford the swelling property. CD and UV-vis spectra demonstrate the optical activity of the microspheres. The microspheres preferably adsorb (R)-(+)-1-phenylethylamine, (R)-(+)-N-benzyl-1-phenylethylamine, and Boc-D-alanine, whereas released Boc-L-alanine rather more rapidly than its enantiomer.

This work was committed to the polymerization of hydrophobic ketoethyl methacrylate monomer in aqueous medium in the presence of cyclodextrin, instead of polymerizing the monomer in toxic and volatile organic solvents. For this purpose, a new ketoethyl methacrylate monomer, p-methylphenacylmethacrylate (MPMA), was synthesized from the reaction of p-methylphenacylbromide with sodium methacrylate in the presence of triethylbenzylammonium chloride. The monomer was identified with FTIR, ¹H and ¹³C-NMR spectroscopies. Hydroxypropyl-β-cyclodextrin (HPCD) was used to form a water-soluble host/guest inclusion complex (MPMA/HPCD) with the hydrophobic monomer. The complex was identified with FTIR and NMR techniques and polymerized in aqueous medium using potassium persulfate as initiator. During polymerization the resulting hydrophobic methacrylate polymer precipitated out with a majority of HPCD left in solution and a minority of HPCD bonded on the resulting polymer. The thus-prepared polymer exhibited little difference from the counterparts obtained in organic solvent in number average molecular weight (M_n), polydispersity (M_w/M_n) and yield. The investigation provides a novel strategy for preparing hydrophobic ketoethyl methacrylate polymer in aqueous medium by using a monomer/HPCD inclusion complex. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

This article reports a class of nanoscale materials, that is, optically active nanoparticles consisting of helical-substituted polyacetylenes. Such nanoparticles were prepared via aqueous catalytic miniemulsion polymerization, by which nanoparticles with a wide range of size (diameter: 60–400 nm) can be easily prepared. The nanoparticles could be obtained in quantitative monomer conversions. Large specific rotations and intense circular dichroism effects demonstrated that the nanoparticles possessed large optical activities; moreover, the optical activities were found to increase with a decrease in particle size. From the obtained polymer nanoparticles and with poly(vinyl alcohol) (PVA) as supporting material, composite films were further prepared and also exhibited considerable optical activities. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1661–1668, 2010

A facile methodology was developed to prepare a novel type of core/shell nanoparticles (NPs) with optical activity and with chemical bonds between the cores and shells. The cores were prepared via catalytic emulsion copolymerization of substituted acetylene comonomers in which one monomer contains azo groups in side chains. For preparing the core/shell NPs, the azo groups in the seed particles (i.e., cores) subsequently act as initiators for vinyl monomer to undergo free radical polymerizations, yielding the shells. This situation resulted in chemical bonds between cores and shells. Both the seed emulsion and core/shell nanoparticle emulsion exhibited optical activity, derived from the polyacetylenes adopting helical conformation of predominant handedness. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Polymerization of hydroxypropyl-β-cyclodextrin (HP-β-CD) complex of methyl methacrylate (MMA) (MMA/HP-β-CD) was carried out under UV irradiation in aqueous solution with Irgacure 2959 (4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone) as a photoinitiator at room temperature. The effects of some principal factors, including UV irradiation intensity, initiator concentration, and the ratio of HP-β-CD to MMA, on the polymerization were investigated in detail. Compared to the corresponding thermal polymerization, photo-induced polymerization of the MMA/HP-β-CD complex could be accomplished at a higher speed; the polymerization conversion in photo-induced polymerization reached 94% within 30 min, while it was only 62% for the thermal polymerization of 16 hr at 70°C. The number-average molecular weight (M_n) and polymerization conversion decreased with the increase in UV intensity and initiator concentration. The resulting PMMA precipitated spontaneously from the solution during polymerization in the absence of any precipitator. About 95 wt% of the HP-β-CD remained in the solution after polymerization and the reusability of the residual HP-β-CD was experimentally demonstrated. Copyright © 2008 John Wiley & Sons, Ltd.

This article investigates the photostability of poly(N-propargylamide)s under different conditions, on the basis of which application research for this class of highly functional polymers can be performed. With helical polymer 1 [monomer: CCCH₂NHCOCH(C₂H₅)₂] taken as a representative, some affecting factors, including the ultraviolet (UV)-light intensity, presence of oxygen, far-UV and near-UV light, and temperature, were investigated. It was found that increasing the UV-light intensity accelerated the degradation of polymer 1. When oxygen was present, it also facilitated the degradation. Far-UV light rather than near-UV light played a predominant role in initiating the degradation of polymer main chains. Elevating the temperature of the polymer solution during UV irradiation made the degradation accelerate. Storing the polymer under weak UV light, in the absence of oxygen, and at a low temperature was favorable for keeping the polymer stable. These findings are important not only from a scientific point of view but especially for developing practical applications of this type of polymer on the basis of its photodegradability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

A novel one-step approach is reported to prepare thermosensitive hydrogels simply by using hydroxypropyl-β-cyclodextrin (HP-β-CD)/glycidyl methacrylate (GMA)/N-isopropylacrylamide (NIPAM) system. From GMA and HP-β-CD, HP-β-CD/GMA inclusion complex was prepared and identified with NMR, FTIR, and UV-vis spectroscopies. GMA in the form of HP-β-CD/GMA complex was copolymerized with NIPAM in water with K₂S₂O₈ as initiator, yielding hydrogels designated as poly(NIPAM-CD-GMA). The inclusion of CD in the hydrogels was confirmed by FTIR spectroscopy. The contents of CD and GMA placed considerable influence on the swelling ratio and temperature-sensitivity of the produced hydrogels. The hydrogels bearing CD moieties showed higher swelling ratio and temperature-sensitivity when compared with that without CD. The porous structure of the hydrogels containing CD was observed in the SEM images. Relevant mechanism of the ring-opening reaction of epoxide groups in GMA, the subsequent crosslinking reactions and the formation of hydrogels containing CD moieties were proposed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2193–2201, 2008

This article presents two novel artificial helical polymers, substituted polyacetylenes with urea groups in side chains. Poly(4) and poly(5) can be obtained in high yields (≥97%) and with moderate molecular weights (11,000–14,000). Poly(4) contains chiral centers in side chains, and poly(5) is an achiral polymer. Both of the two polymers adopted helical structures under certain conditions. More interestingly, poly(4) exhibited large specific optical rotations, resulting from the predominant one-handed screw sense. The helical conformation in poly(5) was stable against heat, while poly(4) underwent conformational transition from helix to random coil upon increasing temperature from 0 to 55 °C. Solvents had considerable influence on the stability of the helical conformation in poly(4). The screw sense adopted by the helices was also largely affected by the nature of the solvent. Poly(4-co-5)s formed helical conformation and showed large optical rotations, following the Sergeants and Soldiers rule. By comparing the present two polymers (with one NH groups) with the three polymers previously reported (with two NH groups in side chains), the nature of the hydrogen bonds formed between the neighboring urea groups played big roles in the formation of stable helical conformation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4112–4121, 2008