Efficient Synthesis and Self-Assembly of Segmented Hyperbranched Block Copolymers via RAFT-Mediated Dispersion Polymerization Using Segmented Hyperbranched Macro-RAFT Agents

Although linear block copolymer assemblies derived from polymerization-induced self-assembly (PISA) have been prepared with a wide variety of structures, examples with hyperbranched block copolymer assemblies have remained elusive. In this work, efficient synthesis and self-assembly of segmented hyperbranched block copolymers (SHBCs) were achieved via reversible addition-fragmentation chain-transfer (RAFT)-mediated dispersion polymerization-induced self-assembly (PISA) using segmented hyperbranched macro-RAFT agents. Two different approaches including the R-RAFT approach and the Z-RAFT approach were employed to synthesize SHBCs with an important structural difference. Using the Z-RAFT approach, the solvophobic block always grows in the inner of SHBCs, allowing the efficient synthesis of colloidally stable SHBC assemblies with a variety of morphologies. Finally, further structural control over SHBCs and morphological control over SHBC assemblies were achieved by combining the R-RAFT approach and the Z-RAFT approach or adding a chain-transfer monomer into the RAFT-mediated PISA. This work not only develops a facile method for the efficient synthesis of SHBCs and SHBC assemblies but also provides important insights into the PISA process of nonlinear block copolymers.

Automated summary

In this work, efficient synthesis and self-assembly of segmented hyperbranched block copolymers (SHBCs) were achieved using segmented hyperbranched macro-RAFT agents. The Z-RAFT approach allowed the solvophobic block to grow inside SHBCs, leading to the synthesis of colloidally stable SHBC assemblies with various morphologies. By combining different approaches, further structural and morphological control over SHBCs and SHBC assemblies were achieved. This work not only provides a facile method for the efficient synthesis of SHBCs and SHBC assemblies but also offers important insights into the PISA process of nonlinear block copolymers.