Thermoresponsive Micellization of Poly(ethylene\nglycol)-<i>b</i>-poly(<i>N</i>-isopropylacrylamide) in Water

Abstract

Thermoresponsive micellization of poly(ethylene glycol)-<i>b</i>-poly(<i>N</i>-isopropylacrylamide)\n(PEG₁₁₀-<i>b</i>-PNIPAM₄₄) in water is studied by static light scattering and dynamic light scattering. The\ncritical aggregation temperature of PEG₁₁₀-<i>b</i>-PNIPAM₄₄ is a little higher than homopolymer PNIPAM,\nand it depends on the block copolymer concentration, which increases from 33.7 to 38.4°C when the\ncopolymer concentration decreases from 2.0 to 0.20 mg/mL. Above the critical aggregation temperature,\nthermoresponsive micellization occurs, and the resultant spherical micelles consist of a PNIPAM core\nand a PEG shell. The block copolymer concentration exerts a strong influence on the size and structure\nof the resultant micelles. Micellization of PEG₁₁₀-<i>b</i>-PNIPAM₄₄ at higher copolymer concentration favors\nformation of narrowly distributed, small, and dense micelles, while large, loose micelles or micellar clusters\nform at lower block copolymer concentration.