Thermoresponsive viscosity of polyacrylamide block copolymers synthesised via aqueous Cu-RDRP

Abstract

Aqueous Cu-RDRP was utilized for the rapid synthesis of poly(N-isopropyl acrylamide)-block-poly(2-hydroxyethyl acrylamide) (PNiPAmx-b-PHEAAmy) copolymers with thermo-responsive viscosity. The pre-disproportionation of Cu(I)Br in the presence of an aliphatic tertiary amine (Me6Tren) in water generated nascent Cu(0) and [Cu(II)] complexes and facilitated the rapid synthesis of a series of (block) copolymers with low dispersity values (1.08 < Đ < 1.22) and control over the molecular weight (Mn,SEC ∼ 30,000). The control over the polymerization enabled the design of a series of block copolymers with precision over the segment ratio, which exhibit different thermo-responsive aggregation. Thermal analysis, viscometry and fluorescence measurements gave insights on the effect of composition and temperature alterations rendering the synthesized polymers potential candidates for temperature-dependent applications.