Preparation And Properties Of Optically Active Polymeric Microspheres By Suspension Polymerization

Polymer microspheres have gained significant attention during recent decades,due to their large specific surface area,small-size effect,high diffusivity,high flowability,and morphological diversity.On the other hand,substituted polyacetylenes,as a kind of polymer with special helical main chains,possess excellent optical activity.Meanwhile,.a combination of helical conjugated main chains and functional side groups shall provide a number of advanced funntional materials.The special structure and properties make substituted polyacetylenes widely applied in helical memory,asymmetric catalysis,chiral recognition,chiral release,and enantioselective crystallization.In the above context,the preparation of helical polymer microspheres intergrating the two concepts "polymer microspheres" and "helical structure" will provide significant insights into polymer materials,especially chiral helical polymer materials.In this work,optically active polymer microspheres based on helical substituted polyacetylenes were prepared through suspension polymerization.The effects of co-solvents on microsphere morphology were investigated in detail.The resulting microspheres were used for chiral adsorption.The main research contents are as follows:1.First,chirally substituted acetylene was copolymerized with alkynyl monomer bearing functional vinyl group to obtain helical macromer.Then,the macromer underwent copolymerization with octadecyl acrylate and butyl acrylate through suspension polymerization with ?-cyclodextrin derivative as crosslinker and PVA as stabilizer to prepare optically active microspheres.The microspheres were characterized with FT-IR,NMR,SEM,CD and UV-vis absorption measurements.The microspheres exhibited large oil-absorbency,reaching up to 68.7 g·g-1 towards CHC13.Using D/L-menthol as model,the microspheres showed remarkable chiral recognition/release ability.2.The effects of co-solvents on preparing substituted polyacetylene microspheres via suspension polymerization were investigated by using THF,DMF,DMSO,DCM,CHC13,and CYC as co-solvents.The results indicated that using oil-soluble co-solvents(DCM,CHC13,and CYC)could promote the formation of micron-sized microspheres and the microsphere size decreased with the increase of co-solvent polarity.Additionally,the water-soluble co-solvents(THF,DMF,and DMSO)could promote the formation of microspheres derived from liquid monomers.The effect of water-soluble co-solvents on microsphere size were the same as abserved in oil-soluble co-solvents.