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

Abstract

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.

Facile synthesis and self-assembly behaviors of biodegradable amphiphilic hyperbranched copolymers with reducible poly(caprolactone) grafts

“…Therefore, from this point, the appearance of a detectable shoulder peak in the SEC trace probably suggests the formation of a highly branched macromolecular structure via the polymerization of vinyl groups of ACP. 34,35…”

“…Therefore, from this point, the appearance of a detectable shoulder peak in the SEC trace probably suggests the formation of a highly branched macromolecular structure via the polymerization of vinyl groups of ACP. 34,35 The degree of branching (DB), number-averaged CTA functionality ( f CTA ), and number-averaged segment numbers of POEGMA(m) and P(HSEMA-g-CL) (n) grafts per copolymer are important parameters of a hyperbranched copolymer, which could be calculated as follows:…”

Efficient Synthesis and PISA Behavior of Molecular Bottlebrush Block Copolymers via a Grafting-From Strategy through RAFT Dispersion Polymerization

“…PISA provides a remarkably efficient and versatile platform for the scalable synthesis of block copolymer (BCP) assemblies with the bespoke size and morphology. − Despite the most PISA studies being focused on the linear BCPs, the copolymers with the architecture beyond linear BCPs, including miktoarm star copolymers, − surface-anchored BCPs, − and branched BCPs, − have also attracted increasing attentions. For instance, Zhang et al.…”

A3B-type miktoarm star polymer nanoassemblies prepared by reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization

“…It has been well established that the morphologies obtained by PISA are largely dictated by the respective chemical nature and length of solvophilic and solvophobic blocks, 45,46 solids, 47,48 solution conditions [49][50][51] and initiating methods. 52 Compared with the vast majority of research on linear diblock and triblock copolymers, the self-assembling behavior of polymers with more complex architectures under PISA conditions 15,[53][54][55][56][57][58][59] has been much less explored. Zhang et al 60 have reported (P4VP-b-PS) n nanoassemblies with arm number n = 1-4, showing that star-shaped BCPs have more complex morphology than their linear counterparts.…”

“…Compared with the vast majority of research on linear diblock and triblock copolymers, the self-assembling behavior of polymers with more complex architectures under PISA conditions 15,53–59 has been much less explored. Zhang et al 60 have reported (P4VP- b -PS) n nanoassemblies with arm number n = 1–4, showing that star-shaped BCPs have more complex morphology than their linear counterparts.…”