Phenols and carbon compounds as efficient organic catalysts for reversible chain transfer catalyzed living radical polymerization (RTCP)

Simple phenols and hydrocarbons were used as novel and efficient organic catalysts for reversible chain transfer catalyzed living radical polymerization (RTCP). This is the first use of oxygen- and carbon-centered compounds as catalysts of living radical polymerization. The catalysts include such common compounds as phenol itself, phenol-based antioxidants for foods and resins (e.g., 3,5-di-tert-butyl-4-hydroxytoluene (BHT)), phenol-based natural antioxidants (e.g., vitamin E), and dienes (e.g., 1,4-cyclohexadiene). Their cheapness, excellent environmental safety, and ease of handing may be quite attractive in practice. The catalysts were highly active and tolerant to functional groups. The required amounts of the catalysts were typically as small as 100-500 ppm, yielding low-polydispersity polymers (M_w/M _n ∼ 1.1-1.4) at moderate temperatures (40-100 °C), where M_w and M_n are weight- and number-average molecular weights, respectively. A wide variety of functional monomers with alkyl, aryl, hydroxyl, poly(ethylene glycol), alkylamino, amino, and carboxylic acid groups were adopted to the homo- and copolymerizations. Kinetic studies supported that, mechanistically, the polymerization is based on reversible chain transfer (RT) for these catalysts.