Advances in Polymerizations Modulated by External Stimuli

Abstract

Synthetic polymer chemistry endeavors to imitate the spatial and temporal control exhibited within biological systems to obtain well-defined polymeric materials with unique structures, properties, and applications. This is often approached through the development of dynamic catalyst (or initiator) systems that use external stimuli to elicit discrete, site-specific transformations that impact the polymerization. Herein we highlight developments in polymerizations that are modulated by external stimuli, with particular focus on those systems that enable notable changes in kinetics, monomer selectivity, polymer architecture, or tacticity. Examples of external stimuli include chemical oxidants or reductants, light, applied voltage, and mechanical force.

Sono‐Fenton Chemistry Converts Phenol and Phenyl Derivatives into Polyphenols for Engineering Surface Coatings

“…The generation of . OH using high‐frequency ultrasound is due to acoustic cavitation, [18, 22] which could induce the hydroxylation/phenolation of phenol to form catechol or pyrogallol groups as well as their oligomers. As shown in Figure S12, phenolated phenol as well as dimers, trimers, and oligomers of phenol were obtained after sonication for 2 h. Table S1 summarizes the possible products formed, including catechol, hydroquinone, pyrogallol, and their dimers.…”

Porphyrin-based donor–acceptor COFs as efficient and reusable photocatalysts for PET-RAFT polymerization under broad spectrum excitation

“…11 In light of these attractive features, COFs have been explored as PCs for a variety of reactions and applications, including hydrogen evolution, 12,13 carbon dioxide reduction, 14 degradation of organic pollutants, 15 and other organic transformations. [16][17][18] Recently, there has been signicant interest in the development of PCs for reversible deactivation radical polymerization (RDRP) methodologies, [19][20][21] such as atom transfer radical polymerization (ATRP) 22 and reversible addition-fragmentation chain-transfer (RAFT) polymerization. 23 The use of PCs for polymerizations offers access to well-dened polymeric materials with complex architectures under mild reaction conditions, 20 and heterogeneous PCs offer added advantages such as easy separation, recycling, and excellent purity of the nal product free of catalysts contaminants.…”

Ortho-vanillin derived Al(iii) and Co(iii) catalyst systems for switchable catalysis using ε-decalactone, phthalic anhydride and cyclohexene oxide

“…25 Although the block copolyesters targeted in this work are accessed through a switch in catalytic mechanism, there are several other methods through which 'switches' in catalytic selectivity can be achieved, resulting in changes of monomer selectivity in a range of catalysts. 26 In particular, electrochemical switches have been utilised to synthesise a range of poly(lactide-b-ether) copolymers. 27,28 Such copolymers have been demonstrated to display favourable mechanical properties when compared to PLA.…”