Polymers with multiple functions: α,ω-macromolecular photoinitiators/chain transfer agents used in aqueous photoinitiated polymerization-induced self-assembly

Abstract

Photoinitiated polymerization-induced self-assembly (photo-PISA) is an emerging method for scalable preparation of block copolymer nanoparticles at room temperature. However, the use of small molecular photoinitiators in photo-PISA is detrimental to further applications of block copolymer nanoparticles. Herein, α,ω-functionalized polymers with a photoinitiator end group and a RAFT end group were synthesized and employed as macromolecular photoinitiators/chain transfer agents in aqueous photo-PISA at room temperature. A kinetic study suggested that photo-PISA exhibited a high rate of polymerization with near quantitative monomer conversion being achieved within 30 min. Gel permeation chromatography (GPC) analysis indicated that moderate RAFT controllability was achieved during photo-PISA. The effects of the degree of polymerization (DP) of the core-forming block, the monomer concentration, and the DP of the α,ω-macromolecular photoinitiator/chain transfer agent on the morphologies of block copolymer nanoparticles were investigated. Finally, a direct comparison between thermally initiated PISA and photo-PISA using the α,ω-macromolecular photoinitiator/chain transfer agent was performed. This study not only expands the scope of photo-PISA, but also provides mechanistic insights into the process of polymerization-induced self-assembly.