Preparation And Properties Of Chiral Helical Substituted Polyacetylene-based Composite Particles

Chiral materials,as a unique type of functional materials,have attracted more and more attention because of their interesting optical activity.Chiral helical substituted polyacetylene backbones can form a one-handed helical structure leading to "chiral amplification effect",which makes the chiral helical substituted polyacetylene materials especially attractive.Therefore chiral helical substituted polyacetylene materials have been widely explored in chiral-related research areas for example chiral recognition,chiral drugs controlled release,and enantioselective crystallization.On the other hand,polymer particles have outstanding properties such as small volume and large surface area.However,chiral helical substituted polyacetylene materials exhibit some disadvantages of relatively high brittleness,low strength and poor processing properties due to the conjugated polymer main chains.The preparation of chiral composite particles by combining chiral helical substituted polyacetylene with other materials possessing excellent properties can hopefully overcome these disadvantages;moreover,the resulting composite particles are expected to exert their advantages as chiral materials.In this study,three new types of chiral composite particles were designed and prepared,and their morphology and properties were further explored.The study may be of large value for the research fields of chiral chemistry,materials science and life science.The main research contents are as follows:1.A chiral helical substituted polyacetylene with vinyl groups was synthesized as a macro-monomer.Chiral helical substituted polyacetylene/POSS composite particles were prepared via suspension copolymerization of macro-monomer and octavinyl polyhedral oligomeric silsesquioxane(OvPOSS),an organic/inorganic hybrid molecule.With the addition of OvPOSS,the composite particles formed porous surface structure and the thermal stability was remarkably improved.The characterization of circular dichroism(CD)and ultraviolet spectroscopy(UV)demonstrated that the substituted polyacetylene backbone of the composite particles formed a one-handed helical structure and exhibits desirable optical activity.2.Firstly,the functional cross-linked particles with epoxy groups on the surface were prepared by precipitation polymerization using glycidyl methacrylate(GMA)and divinylbenzene(DVB)and used as the "cores".The chiral helical substituted polyacetylene formed an optically active shell on the surface of "core" by seed-surface graft precipitation polymerization to obtain optically active core-shell composite particles.The results of SEM,elemental analysis and XPS demonstrated that the core-shell composite particles were successfully prepared.By characterizing of CD and UV,it could be illustrated that the core-shell composite particles have good optical activity,and the optical activity was derived from the chiral helical substituted polyacetylene shell.3.Syringaldehyde methacrylate(SMA)was synthesized from the renewable biomass syringaldehyde.The bio-based functional particles with plenty of aldehyde groups were prepared from SMA via precipitation polymerization using DVB as a cross-linking agent.According to the above study,bio-based optically active core-shell composite particles were obtained by seed-surface graft precipitation polymerization.Core-shell composite particles were characterized by SEM and elemental analysis,which was proved that the particles have a core/shell structure in which the inner layer was the bio-based vinyl polymer and the outer layer was the chiral helical substituted polyacetylene.In addition,the optimum monomer concentration for preparing the core-shell composite particles was found.The core-shell composite particles exhibited excellent optical activity characterized by CD and UV.