The synthesis of P(MAn-co-St)-b-PS-b-P(MAn-co-St) block copolymers by RAFT polymerization and the nanostructure of their self-assembly aggregates

A series of block copolymers of styrene, maleic anhydride and acrylic acid were synthesized by the reverse addition–fragmentation chain transfer (RAFT) process. The structure, molecular weight and polydispersity index were determined by FTIR, 1H NMR, SEC&MALLS and DSC analysis. The results showed that the polymerization occurred in a living and controlled manner. Multiple self-assembled nanostructures of these block copolymers were investigated by transmission electron microscopy (TEM). Tetrahydrofuran (THF), N,N-dimethylformamide (DMF) and 1,4-dioxane were used as the common solvents and twice-distilled water as the selective solvent to clarify the effects of the solvent. The results revealed that with the increase of the extension degree of the core, non-spherical aggregates were easily formed, the composition of the copolymers influences the aggregation behavior, and other factors also influence the self-assembly, such as hydrolysis, temperature, annealing time, molecular architecture etc. A mechanism is proposed to illustrate the formation of the various aggregates of P(MAn-co-St)-b-PS-b-P(MAn-co-St) copolymer, which were confirmed by TEM results.