In situ cross-linking in RAFT-mediated emulsion polymerization: Reshaping the preparation of cross-linked block copolymer nano-objects by polymerization-induced self-assembly. (16th September 2021)

• Record Type: Journal Article
• Authors: Cao, Junpeng; Tan, Yingxin; Dai, Xiaocong; Chen, Ying; Zhang, Li; Tan, Jianbo
• Is Part Of: Polymer. Volume 230(2021)
• Publication Date: 2021-09-16
• Subjects: Polymerization-induced self-assembly -- RAFT-Mediated emulsion polymerization -- Cross-linking; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2021.124095
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Large-scale preparation of cross-linked block copolymer nano-objects using polymerization-induced self-assembly (PISA) generally suffers from the limitation that high degrees of cross-linking in the early stage must be avoided. Herein, we demonstrate that the intrinsic monomer-feeding mechanism of reversible addition-fragmentation chain transfer (RAFT)-mediated emulsion polymerization can be used to delay in situ cross-linking during PISA, allowing the preparation of cross-linked block copolymer nano-objects with high cross-linker contents. When using hydrophobic cross-linkers, the cross-linker along with monomer diffuses from monomer droplets to micelles gradually. When using hydrophilic cross-linkers, the cross-linker is prone to stay in water rather than diffuse into hydrophobic micellar cores. 1 H NMR analysis confirmed the consumption behavior of cross-linkers during RAFT-mediated emulsion polymerization regardless of cross-linkers used. A variety of cross-linkers with different aqueous solubilities, symmetries, and functional groups were employed to prepare cross-linked block copolymer nano-objects. It is demonstrated that increasing the content of cross-linker promoted the formation of higher-order morphologies. We expect this study will not only expand the scope of RAFT-mediated PISA for in situ preparation of cross-linked block copolymer nano-objects, but also inspires researchers in this field to prepare novel polymer nanoparticles based on the unique mechanism of RAFT-mediated emulsion polymerization. Graphical abstract: Image 1 Highlights: RAFT-mediated emulsion polymerization is employed to delay in situ cross-linking. Cross-linked block copolymer nano-objects with various morphologies are prepared. A variety of cross-linkers are employed to prepare cross-linked block copolymer nano-objects.