Role of High‐Molecular‐Weight Homopolymers on Block Copolymer Self‐Assembly: From Morphology Modifier to Template

• Published in: Macromolecular chemistry and physics Vol. 220; no. 3
• Main Authors: Zhang, Shuo, Cai, Chunhua, Xu, Zhanwen, Lin, Jiaping, Jin, Xiao
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.02.2019
• Subjects: Assembly; Block copolymers; Chemical industry; Globules; homopolymers; Micelles; Molecular weight; Morphology; morphology modifiers; Polyethylene glycol; Polystyrene resins; self‐assembly; templates
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.201800443

For block copolymer (BCP)/homopolymer self‐assembly systems, the molecular weight of homopolymers is usually lower than that of BCPs. Herein, the cooperative self‐assembly of polystyrene‐b‐poly(ethylene glycol) (PS‐b‐PEG) BCPs with high‐molecular‐weight polystyrene (PS) homopolymers is reported. The molecular weight of PS homopolymers is 3–63 times that of the PS blocks. Typically, a spherical micelle–vesicle–large sphere morphology transition is observed by increasing the weight fraction of PS homopolymers in the polymer mixtures (f HP). Dynamic process studies reveal that with adding water to the solution of polymer mixtures in organic solvent, the homopolymers first collapse into globules, and their size increases with f HP and the molecular weight. Then these PS globules cooperatively self‐assemble with the PS‐b‐PEG BCPs. Depending on their size, these PS globules play different roles in the self‐assembly process. Small PS globules act as morphology modifiers inducing the micelle–vesicle transition, while large PS globules serve as self‐assembly templates for PS‐b‐PEG resulting in large spheres. High‐molecular‐weight polystyrene (PS) homopolymers are found in the form of globules to cooperatively self‐assemble with polystyrene‐b‐poly(ethylene glycol) (PS‐b‐PEG) block copolymers. Depending on their size, these PS globules play different roles. Small PS globules act as morphology modifiers inducing the micelle–vesicle transition, while large PS globules serve as self‐assembly templates for PS‐b‐PEG resulting large spheres.