Star Architecture Promoting Morphological Transitions during Polymerization-Induced Self-Assembly

Abstract

Polymerization-induced self-assembly (PISA) via reversible addition−fragmentation chain transfer (RAFT) dispersion polymerization is an effective method to produce block copolymer nano-objects of various morphologies at high solids. However, current PISA formulations have been limited to linear block copolymers. We report the synthesis of AB 2 star block copolymers via RAFT aqueous dispersion polymerization of diacetone acrylamide using a poly(ethylene glycol) methyl ether bearing two chain transfer agents as the difunctional macromolecular chain transfer agent (macro-CTA), which was efficiently synthesized using 2,4,6trichloro-1,3,5-triazine and activated esters to afford a high end functionality (97%). The star polymer architecture can significantly promote morphological transitions to obtain higher-order morphologies at both lower solids and lower degrees of polymerization of the core-forming block in comparison with its linear counterpart. This work demonstrates that polymer architecture is another important parameter that should be considered when conducting PISA synthesis to obtain complex morphologies.

Beyond Simple AB Diblock Copolymers: Application of Bifunctional and Trifunctional RAFT Agents to PISA in Water

“…In pure water, in particular, there are only a handful of reports beyond diblock copolymers, most of them based on linear block copolymers (triblock or multiblock) and to the best of our knowledge, there is only one example based on a more complex Y‐shape architecture (AB 2 ). This latter structure was formed via RAFT dispersion polymerization of diacetone acrylamide (DAAm) in water using a ω‐bifunctional poly(ethylene glycol) (PEG) macro‐CTA . The authors compared the morphologies obtained with those from a monofunctional macro‐RAFT agent, yielding conventional PEG‐ b ‐PDAAm diblock copolymers, and demonstrated that the Y‐shaped copolymer, PEG‐ b ‐(PDAAm) 2 , promotes the production of nanoobjects with high‐order morphologies through the formation of bulky hydrophobic segments.…”

Loop-stabilized BAB triblock copolymer morphologies by PISA in water

“…1,3,6,7 Another important parameter, that has received much less attention so far in PISA, should be the macromolecular architecture of the polymer chains. Hitherto there are only few reports in the literature comparing notably linear chains with stars or branched structures, 13,14 diblocks with triblocks or multiblocks [15][16][17][18][19][20][21][22] in PISA. Nonetheless, most of the studied systems are currently based on simple AB diblock copolymers, where A is the solvophilic, stabilizer block, and B is the solvophobic block.…”

Controlling Nanomaterial Size and Shape for Biomedical Applications via Polymerization‐Induced Self‐Assembly

“…In a recent work, Wang et al. investigated the effect of polymer architecture on the morphology of diblock copolymers synthesized via PISA . A novel difunctional poly(ethylene glycol) (PEG)‐based macro‐CTA was synthesized.…”