Efficient Photoinitiated Polymerization-Induced Self-Assembly with Oxygen Tolerance through Dual-Wavelength Type I Photoinitiation and Photoinduced Deoxygenation

Recently, reversible addition-fragmentation chain transfer (RAFT)-mediated polymerization-induced self-assembly (PISA) has emerged as a powerful method for the preparation of a variety of block copolymer nano-objects. Although numerous RAFT-mediated PISA formulations have been successfully explored, inert atmospheres (e.g., nitrogen) are often needed to overcome the oxygen inhibition problem, making this process challenging when polymerizing at low volumes. Moreover, this restriction also reduces the versatility of RAFT-mediated PISA for non-experts. Herein, we report an efficient photoinitiated polymerization-induced self-assembly (photo-PISA) with excellent oxygen tolerance through dual-wavelength type I photoinitiation and photoinduced deoxygenation. The dual-wavelength photo-PISA was explored in water and alcohol/water using 2-hydroxypropyl methacrylate (HPMA), benzyl methacrylate (BzMA), and isobornyl acrylate (IBOA) as core-forming monomers. Polymerization kinetics indicated that dual-wavelength photo-PISA was performed in a batch reactor, flow reactor, and microliter plate with excellent oxygen tolerance. Block copolymer nano-objects with different morphologies (spheres, worms, and vesicles) were successfully prepared by these dual-wavelength photo-PISA techniques. This is a fast RAFT-mediated PISA under air, which is a clear improvement from previous systems. We believe that this method can greatly increase the accessibility of RAFT-mediated PISA for the preparation of block copolymer nano-objects either at low volumes or at a large scale.