Synthesis of heteroarm core cross-linked star polymers and control of intramolecular segregation towards janus polymer nanoparticles

Abstract

In this thesis, we explored a rational approach to synthesize intramolecularly segregated heteroarm core cross-linked star (CCS) polymers. By utilizing reversible addition-fragmentation chain transfer (RAFT) copolymerization of excess styrene (S) and bismaleimide (BMI) that proceeds in an alternating fashion in the presence of polylactide (PLA) macro-chain transfer agent (PLA-CTA), we obtained heteroarm CCS polymers (PLA$_n$PS$_n$) consisting of PLA and polystyrene (PS). Also we investigated the self-assembly behavior of PLA$_n$PS$_n$ to understand the influence of synthetic routes (e.g. “in-out” method, “multi macro-initiator (MI)” method) to the degree of intramolecular segregation. The PLAnPSns obtained via “in-out” in acetonitrile (selective solvent to PLA) were formed nearly uniform supermicelles in acetonitrile, indicating their Janus-like characters. Furthermore, we proposed another way to fabricate heteroarm CCS polymers with compartmentalized shell via sequential “in-out” polymerization induced self-assembly (PISA) approach. Subsequent chain extension of dodecyl acrylate (DA) in the presence of PLA CCS polymers produced intramolecularly segregated PLA$_n$PDA$_n$, simultaneously leading to formation of 1D segmented wormlike micelles.