Search for: All records

This chapter highlights the current advancements in reversible-deactivation radical polymerization (RDRP) with a specific focus on atom transfer radical polymerization (ATRP). The chapter begins with highlighting the termination pathways for acrylates radicals that were recently explored via RDRP techniques. This led to a better understanding of the catalytic radical termination (CRT) in ATRP for acrylate radicals. The designed new ligands for ATRP also enabled the suppression of CRT and increased chain end functionality. In addition, further mechanistic understandings of SARA-ATRP with Cu0 activation and comproportionation were studied using model reactions with different ligands and alkyl halide initiators. Another focus of RDRP in recent years has been on systems that are regulated by external stimuli such as light, electricity, mechanical forces and chemical redox reactions. Recent advancements made in RDRP in the field of complex polymeric architectures, organic-inorganic hybrid materials and bioconjugates have also been summarized. 

This work explores the concept of structurally tailored and engineered macromolecular (STEM) networks by proposing a novel metal-free approach to prepare the networks. STEM networks are composed of polymer networks with latent initiator sites affording post-synthesis modification. The proposed approach relies on selectively activating the fragmentation of trithiocarbonate RAFT agent by relying on visible light RAFT iniferter photolysis coupled with RAFT addition–fragmentation process. The two-step synthesis explored in this work generates networks that are compositionally and mechanically differentiated than their pristine network. In addition, by careful selection of crosslinkers, conventional poly(ethylene glycol) dimethacrylate ( M n = 750) or trithiocarbonate dimethacrylate crosslinker (bis[(2-propionate)ethyl methacrylate] trithiocarbonate (bisPEMAT)), and varying concentrations of RAFT inimer (2-(2-( n -butyltrithiocarbonate)-propionate)ethyl methacrylate (BTPEMA)), three different types of primary (STEM-0) poly(methyl methacrylate) (PMMA) networks were generated under green light irradiation. These networks were then modified with methyl acrylate (MA) or N , N -dimethylacrylamide (DMA), under blue light irradiation to yield STEM-1 gels that are either stiffer or softer with different responses to polarity (hydrophilicity/hydrophobicity).