The Synthesis Of Amphiphilic Polymer Containing P4VP By RAFT And Its Self-assembly

The radical polymerization of styrene (St) or4-vinylpyridine (4-VP) with2-(ethoxycarbonyl) prop-2-yl dithiobenzoate (EPDB) as reversibleaddition-fragmentation chain transfer polymerization (RAFT) agent,azodiisobutyronitrile (AIBN) as initiator was investigated in this study, andpolystyrene-b-poly(4-vinylpyridine)(PS-b-P4VP) diblock copolymer wasprepared by RAFT, then the amphiphilic polymers, QP4VP and PS-b-QP4VPwere prepared by quaternarization of P4VP and PS-b-P4VP with excessn-butyl bromide (n-BuBr) or1-bromohexadecane. The morphologies ofaggregates of QP4VP and PS-b-QP4VP in water were investigated.The molecular weight, distribution of the copolymers, structures and thedegrees of quaternization of QP4VP block were determined by1H-NMR,GPC and FI-IR, respectively. The multiple morphologies, cmc and dimendionsof the aggregates were characterized by TEM, surface tension and DLS. In thepresent paper, we discuss mainly the effects of copolymer composition, theinitial copolymer concentration, the nature of the solvent, the ratio of themixture solvent on the morphologies of QP4VP crew-cut aggregates.The results showed that the well-defined P4VP, PS-b-P4VP, QP4VP andPS-b-QP4VP polymers were controllably synthesized by RAFT. Thedistribution of the copolymers was narrow. The degrees of quaternization of QP4VP block were at least90%. On one hand, the CMC of the QP4VP insolution is12.5g/L. The DLS and TEM results showed that the size of theaggregates was increasing with the length of P4VP. On the other hand, withincreasing the initial copolymer concentration or the length of PS in DMF, thesize of the sphere aggregates increases. The morphologies ofPS-b-P4VP BuBr crew-cut aggregates also vary with the solvent, such assphere in DMF, LCMs in THF, and LCVs in dioxane. In addition, rods andvesicular aggregates are obtained by changing the composition of the solvents.