Simultaneous Synthesis and Self‐Assembly of Bottlebrush Block Copolymers at Room Temperature via Photoinitiated RAFT Dispersion Polymerization

Abstract

Bottlebrush polymers exhibiting unique properties have attracted considerable attention for applications in many research areas. Herein, the first simultaneous synthesis and self‐assembly of bottlebrush block copolymers at room temperature via photoinitiated polymerization‐induced self‐assembly (photo‐PISA) using multifunctional macromolecular chain transfer agents (macro‐CTAs) is reported. Comparing with linear block copolymers, the bottlebrush block copolymers can promote the formation of higher‐order morphologies (e.g., vesicles) when targeting similar degrees of polymerization (DPs). Moreover, a higher polymerization rate is observed in the case of bottlebrush block copolymers. Gel permeation chromatography (GPC) analysis shows that good polymerization control is maintained when synthesizing bottlebrush block copolymers by photo‐PISA. Finally, the obtained bottlebrush block copolymer vesicles are used as seeds for further chain extension and multicompartment nanoparticles with a sponge internal structure are formed. It is expected that this study will not only expand polymer architectures employed in PISA, but also provide a new strategy to synthesize polymer nanoparticles with unique structures.

Combining Green Light-Activated Photoiniferter RAFT Polymerization and RAFT Dispersion Polymerization for Graft Copolymer Assemblies

“…Moreover, the obtained block copolymers would self-assemble into colloidally stable polymer assemblies via a polymerization-induced self-assembly (PISA) mechanism. Since 2009, RAFT-PISA has become an emerging approach to produce block copolymer assemblies with diverse morphologies under concentrated conditions (solids content of 10–50% w/w). − …”

“…Since the RAFT-PISA involves the chain extension from a macro-RAFT agent, the structure and composition of the macro-RAFT agent should have a great impact on the nature of RAFT-PISA as well as the obtained block copolymer assemblies. ,,− Currently, the utilization of linear monofunctional or difunctional macro-RAFT agents dominates the research of RAFT-PISA, , and linear block copolymer assemblies are mainly formed. In contrast, the preparation of graft copolymer assemblies via RAFT-PISA mediated by a multifunctional macro-RAFT agent has rarely been reported.…”

Mechanistic Investigation of the Position of Reversible Addition–Fragmentation Chain Transfer (RAFT) Groups in Heterogeneous RAFT Polymerization

“…Typically, macro-RAFT agents are synthesized by either RAFT polymerization or the conjugation between a solvophilic polymer and the fragmenting group (R-group) of a RAFT agent. ,,− As a result, the RAFT groups are always located at the terminus of the formed diblock copolymers during heterogeneous RAFT polymerization, leading to the formation of block copolymer nanoparticles with embedded RAFT groups. This characteristic is particularly important for the control over colloidal stability and molar mass in heterogeneous RAFT polymerization, since the polymerization locus is mainly inside particles after the micellar nucleation .…”

Polymerization-induced self-assembly of random bottlebrush copolymers

“…Tan et al further compared the PISA behaviors of brush-linear and block BBCPs. 46 Using photo-RAFT polymerization, they prepared a series of amphiphilic block BBCPs, where the hydrophilic block was poly[ poly(ethylene glycol) methyl ether methacrylate] (PPEGMA), while the side-chain of the hydrophobic block was poly(2-hydroxypropyl methacrylate) (PHPMA) (Scheme 1b). Interestingly, the block BBCPs favor higher-order morphologies compared to the brush-linear copolymers under the same hydrophilic/hydrophobic ratio, which underlies the significance of steric repulsion among the adjacent side-chains to the self-assembly of BBCPs.…”