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This article reports the first optically active macroporous materials constructed by helical substituted polyacetylene and prepared by a high internal phase emulsion (HIPE) technique. The macroporous (∼3 μm) materials were fabricated simply through polymerization of the continuous phase in HIPEs. The porous structures of the resulting materials can be adjusted by varying the fraction of the dispersed phase. The obtained materials were characterized by regular pore morphology, high porosity, and low density. Circular dichroism and UV-vis absorption spectra demonstrated that the substituted polyacetylene forming the materials adopted chirally helical conformations, which endowed the materials with considerable optical activity. The optically active porous materials were used as chiral inducers and efficiently induced enantioselective crystallization of threonine and alanine racemates. l-Threonine and l-alanine were preferably induced to form crystals from the respective racemic solutions. The prepared materials open a new type of functional chiral materials with potential applications in asymmetric catalysis, chiral resolution, etc.

Hybrid materials are interesting because they combine the advantages of multiple components in one material entity. This article reports on a new type of chiral porous hybrid particle constructed by helical substituted polyacetylene and silica. To prepare the hybrid particles, chirally helical substituted acetylene copolymers containing pendent Si–O–Et groups were first synthesized and subsequently used as macromolecular silane couplers to perform a sol–gel reaction with TEOS. After aging, the designed hybrid particles were fabricated. Phase separation in the sol–gel reaction endowed the hybrid particles with abundant pores. In the resulting hybrid particles, inorganic silica constituted the rigid framework, whereas the organic helical substituted polyacetylene bonded with the framework and offered optical activity. SEM images confirmed the formation of spherical particles with regular morphology and porous structure. Circular dichroism and UV-vis absorption spectra demonstrated that the helical polymer chains had a preferential helicity and considerable optical activity in the hybrid particles. The hybrid materials demonstrated the capability of enantioselectively releasing cinchona alkaloid, which was used to model chiral drugs. The release process was found to be influenced by temperature: low temperature was more favorable for enantio-differentiating release.

The present work reports on the synthesis of chiral particles consisting of helical polylactide (PLA) and helical substituted polyacetylene, aiming to investigate the chiral synergetic effects of the two helical components in enantioselectivity. For this purpose, polylactide with polymerizable terminal alkynyl group was prepared and subsequently used as macromer to copolymerize with chiral alkynyl monomer to form the target particles. SEM images demonstrate that the particles possessed porous structures. Circular dichroism shows that the helical substituted polyacetylene had an influence on the helical screw sense of polylactide chains, thereby affecting the enantioselectivity of the chiral particles in releasing the model chiral drug naproxen. Compared with our earlier study on enantioselectivity of PLA, copolymerizing PLA with chiral alkynyl monomer improves PLA’s enantioselectively discriminating ability in naproxen release and even can reverse the particles’ preferential enantioselectivity in releasin...

Incorporating multi-functions into a single entity can provide various novel materials, well exemplified by interpenetrating polymer networks. In this contribution, we prepared the first chiral porous interpenetrating polymer networks (IPNs) by incorporating functional boronic acid-containing polymers to a pre-formed chiral porous framework which was constructed by chirally helical substituted polyacetylenes. The pore size in the resulting chiral IPNs can be tuned by adjusting the content of the boronic acid-containing polymer. Circular dichroism and UV-vis absorption spectra demonstrated that the helical polymer chains in both the pre-formed chiral porous framework and the final IPNs took preferential helicity, which rendered the IPNs with considerable optical activity. The as-prepared IPNs could adsorb glucose through esterification reaction occurring between the boronic acid groups contained in the networks and cis-diol in glucose. More importantly, the successful combination of boronic acid groups with the chiral framework enabled the IPNs to simultaneously exhibit enantioselectivity and pH sensitivity in the glucose adsorption process. The reversibility of the boronic acid-derived ester structure facilitated the IPNs to be easily recycled, thus endowing the novel IPNs with diverse promising applications.

The double helix is one of the most basic and exquisite architectures in nature, and thus has received much attention in multiple disciplines. However, the types of artificial polymeric double helices and their synthetic methods are severely limited. The present contribution develops a novel 3-step methodology for preparing double helices consisting of helical substituted polyacetylenes (DHSPs): (1) an optically inactive helical polymer is synthesized using an achiral monomer; (2) the as-obtained polymer is induced to form a one-handed helix by “locking” a chiral monomer in the helical grooves; (3) the “locked” chiral monomer undergoes helically twining polymerization along the pre-formed one-handed helical polymer chains, thereby constructing the DHSPs. Circular dichroism and UV-vis absorption spectra in combination with high resolution TEM images demonstrate the optical activity, double helical structure, and helix sense of the DHSPs. The convenient synthetic strategy is expected to provide various kinds of double helical polymers.

A judicious combination of chiral structure with other functionalities in one entity may provide novel materials. For this purpose, boronic acid functional group was integrated with optically active helical substituted polyacetylene microspheres. To prepare the designed functional microspheres, two substituted acetylene monomers, i.e. chiral monomer M1 and achiral monomer M2 which was prepared from a boronic acid derivative, were synthesized and copolymerized through suspension polymerization for constructing polymeric microspheres. SEM images demonstrated the successful formation of the microspheres. X-ray photoelectron spectroscopy was measured to determine boronic acid content on the surface of the as-prepared microspheres. Circular dichroism spectra showed that one-handed helices were formed in the copolymer chains constructing the microspheres, which enabled the microspheres to exhibit enantio-differentiating adsorption capacity towards 3,4-dihydroxy-l-phenylalanine (l-DOPA), whereas 3,4-dihydroxy-d-phenylalanine (d-DOPA) was preferentially released. Amazing synergistic effects occurred in the helical polymer chains and the pendant boronic acid moieties. Desorption capacity and recyclability of the microspheres were also clearly verified. The unprecedented optically active microspheres hold practical applications for developing materials used for chiral adsorption, enantiomeric drug controlled release, etc.

The importance of chiral compounds has been widely recognized. Enantioselectively controlled release of the desired enantiomer from a racemate while retarding the other isomer provides a novel route toward practical applications of biologically chiral molecules. Such processes may maximize the efficacy while minimizing the dosage and frequency of chiral compounds. So far, exciting achievements have been made in enantioselective release (ESR), which can be classified into two main groups according to the essential strategy: (1) chiral interactions occurring between chiral compounds and chiral matrices (“enantioselective interaction” strategy); and (2) recognizing sites inside molecular-imprinting polymers (MIPs; “key-to-lock” strategy). The chiral compounds of interest are not limited to chiral drugs, but also include other biologically important chiral compounds (e.g., amino acids). Based on our studies, this article reviews the state-of-the-art techniques and materials systems toward ESR. The emphasis is...

This article reports a novel type of polymeric microspheres derived from a renewable biomass, eugenol, via a facile and effective suspension polymerization approach. On the basis of eugenol and methacryloyl chloride, we first synthesized and then structurally identified the monomer eugenyl methacrylate (E-MA). By using E-MA as the sole monomer and simultaneously as the cross-linking agent, we successfully prepared cross-linked polymeric microspheres through suspension polymerization in aqueous media with 2,2-azoisobutyronitrile (AIBN) as the initiator and poly(vinyl alcohol) (PVA) as the stabilizer. The resulting microspheres were obtained in high yield with diameters ranging 500–800 μm and exhibited remarkably large oil absorbency in a relatively high speed. The microspheres can be reused for at least five times with little change in maximum absorption. The preparative strategy for the polymeric microspheres can be taken as a versatile platform for preparing more functional polymeric microspheres, which ...