Hydroxyethyl Acrylate-Based Polymeric Amphiphiles Showing Lower Critical Solution Temperature

Abstract

Poly(2-hydroxyethyl acrylate-co-methylmethacrylate) (P(HEA-MMA)) and poly(2-hydroxyethyl acrylate-co-butylmethacrylate) (P(HEA-BMA)) were prepared as thermo-sensitive amphiphilic polymers. When HEA was copolymerized with MMA so that MMA content was 2.1% (mol/mol), the optical density of P(HEA-MMA) solution began to increase around 37°C. The lower critical solution temperature (LCST) decreased as the MMA content increased. When HEA was copolymerized with BMA so that BMA content was 2.2%, P(HEA-BMA) exhibited its LCST around 37°C, and the LCST also decreased with increasing the BMA content. BMA was more effective than MMA in promoting the thermally-induced collapse of polymer chains. As the content of the hydrophobic co-monomers increased, the air/water interfacial tension increased. The mean diameter of the micelle of P(HEA-MMA)s and that of the micelle of P(HEA-BMA)s changed in a fluctuated and temperature-dependent manner. On TEM photos, no marked difference was found in the size and the shape between P(HEA-MMA) micelles and P(HEA-BMA) ones.