One-Step Photocontrolled Polymerization-Induced Self-Assembly (Photo-PISA) by Using In Situ Bromine-Iodine Transformation Reversible-Deactivation Radical Polymerization

Polymerization-induced self-assembly (PISA) has become an effective strategy to synthesize high solid content polymeric nanoparticles with various morphologies in situ. In this work, one-step PISA was achieved by in situ photocontrolled bromine-iodine transformation reversible-deactivation radical polymerization (hereinafter referred to as Photo-BIT-RDRP). The water-soluble macroinitiator precursor alpha-bromophenylacetate polyethylene glycol monomethyl ether ester (mPEG(1k)-BPA) was synthesized in advance, and then the polymer nanomicelles (mPEG(1k)-b-PBnMA and mPEG(1k)-b-PHPMA, where BnMA means benzyl methacrylate and HPMA is hydroxypropyl methacrylate) were successfully formed from a PISA process of hydrophobic monomer of BnMA or HPMA under irradiation with blue LED light at room temperature. In addition, the typical living features of the photocontrolled PISA process were confirmed by the linear increase of molecular weights of the resultant amphiphilic block copolymers with monomer conversions and narrow molecular weight distributions (M-w/M-n < 1.20). Importantly, the photocontrolled PISA process is realized by only one-step method by using in situ photo-BIT-RDRP, which avoids the use of transition metal catalysts in the traditional ATRP system, and simplifies the synthesis steps of nanomicelles. This strategy provides a promising pathway to solve the problem of active chain end (C-I) functionality loss in two-step polymerization of BIT-RDRP.