Synthesis And Characterization Of Novel Block Polymers Based On Semi-rigid Thermoresponsive Chain

Temperature-sensitive polymers, as one kind of intelligent polymers, have been attracted great attention recently. It is well known that the main chain of most temperature-sensitive polymers are flexible. Although natural polymer, such as polypeptide and alkyl-substituted celluloses which have semi-rigid main chains, is a kind of temperature-sensitive polymers, the origin of material about these polymers hinder the molecular design and synthesis. Therefore, it is very important that the novel semi-rigid polymers exhibiting temperature sensitive property are designed and synthesized.As we know, Mesogen-Jacketed Liquid Crystal Polymer (MJLCP) is a typical semi-rigid synthesized polymer which is just soluble in organic solvent and hardly water-solubled. We have designed and synthesized a novel polymer based on MJLCP exhibiting both temperature-sensitivitity and liquid crystalline property. We think the polymer would benefit the research of theory and application on the intelligent polymer.Diblock copolymers (DBCPs) can self-assemble into micelles or vesicles when dispersed in a medium that solvates one block selectively. Experimental results showed that variations in micelle structure as a function of block copolymer composition, molecular weight, and concentration would induce the changes of the morphology. Herein, we would design and synthesized a novel BCP based on the semi-rigid temperature-sensitive polymers via Reversible Addition-Fragmentation Chain-Transfer polymerization(RAFT), and investigate the morphology of self-assembly in solution.The amphiphilic block copolymer polystyrene-b-poly(bis(N-hydroxyisopropyl pyrrolidone)-2-vinylterephthalate) (PS-b-PHIPPVTA) is successfully synthesized via RAFT and the bulk properties and solution properties of PS-b-PHIPPVTA were confirmed by DSC, POM, LLS.The experimental results show that the amphiphilic block copolymer PS-b-PHIPPVTA only exhibited a glass transition, which was similar to MJLCPs, at the same time, the block copolymer could display liquid crystalline properties when the molecular weight of semi-rigid chain in the block copolymer reached a specific length. And a kind of disk-like micelle micelles was observed by AFM. The results of LCST show that the thermosensitivity of the BCPs in aqueous solution was strongly dependent on their molecular weight, and their aqueous solution exhibited reversible phase transition.The amphiphilic block copolymer poly(bis(N-hydroxyisopropyl pyrrolidone)-2-vinylterephthalate)-b-poly(N-isopropylacrylamide) (PHIPPVTA-b-PNIAPM) is successfully synthesized via RAFT and the bulk properties and solution properties of PHIPPVTA-b-PNIAPM were confirmed by DSC, POM, LLS.The experimental results show that the amphiphilic block copolymer PHIPPVTA-b-PNIAPM only exhibited a glass transition, which was similar to MJLCPs, at the same time, the block copolymer couldn't display liquid crystalline properties but the macromolecule chain transfer agents display liquid crystalline properties. The results of LCST show that the thermosensitivity of the BCPs in aqueous solution was strongly dependent on heir molecular weight and concentration, and their aqueous solution exhibited reversible phase transition.