Optically Active Polymer Particles Based On Substituted Polyacetylenes:Preparation And Applications

One-handed helical polymers present remarkable optical activity based on the special secondary structures. More interestingly, polymers with helix structure have "chiral amplification effect". Thus one-handed helical polymers hold great potential applications in the fields of chiral enantiomer separation, asymmetric catalysis, etc.In our experiments, we utilized chiral and biocompatible cholic acid and substituted polyacetylenes to successfully prepare optically active polymer particles in micron size by combining coordination polymerization and precipitation polymerization in THF/n-heptane system. An interesting phenomenon was observed, i.e. micro-sized porous particles were obtained simply via varying reaction temperature, namely, no additional porogen agent was added. The particles present remarkable optical activity according to circular dichroism (CD) and polarimeter measurements. The chiral polymer particles were further applied in chiral separation of alanine and BOC-alanine. D-alanine and BOC-L-alanine were preferentially induced to crystalize out of the corresponding racemate. Optical active properties and crystal structure of the induced crystals were measured and further identified by CD, polarimeter and XRD techniques.Optically active polymer nanoparticles were prepared via emulsion polymerization. CD and UV-vis absorption spectra showed that the (co)polymer chains in the nanoparticles adopted helical structures of a predominant helicity, which enabled the copolymer nanoparticles to show optical activity. Compared to the corresponding nanoparticles of the homopolymers, the nanoparticles constructed by the copolymers exhibited blue shifts in CD and UV-vis spectra. The present study demonstrated that the copolymers prepared via emulsion polymerization approach followed the "sergeants and soldiers" rule.