Heteroarm core cross-linked star (CCS) polymers, in which two chemically different polymer arms emerging from a densely cross-linked core, have been received considerable attention due to different self-assembling behaviors compared to linear block analogues. Such nanoobjects revealing two different “faces” via intramolecular segregation are expected to behave as Janus nanoparticles, which will be useful as interfacial stabilizer and emulsifiers. We have recently reported a synthetic route to heteroarm CCS polymers by utilizing reversible addition-fragmentation chain transfer (RAFT) copolymerization of 1,2-bis(maleimidoethane) (BMI) and styrene (S) that proceeds in an alternating fashion. Using an excess of styrene in the presence of polylactide (PLA) macro-chain transfer agent (PLA-CTA), we have demonstrated that PLAnPSn CCS polymer can be synthesized via “in-out” approach including formation of PLAn by alternating copolymerization of S and BMI followed by growth of PS arms from the core after depletion of BMI. Compared with divinylbenzene (DVB) which produces CCS polymers with rather broad dispersities by RAFT polymerization due to intrinsic reversible chain transfer mechanism, use of S/BMI copolymerization seems to facilitate formation of CCS polymers thanks to strong alternating tendency of S/BMI. In this presentation, we will show that this methodology can be extended to synthesis of other heteroarm CCS polymers via different synthetic routes such as “multi macro-initiator” approach. We will discuss synthetic details of heteroarm CCS polymers and their self-assembling behaviors in solution and in bulk to establish structure-property relationship of heteroarm CCS polymers.

Heteroarm core cross-linked star polymers via RAFT alternating copolymerization

253rd National Meeting (2017)

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