Thermoresponsive self-assembled polymer colloids in water

Abstract

Thermoresponsive polymer colloids made of amphiphilic block copolymers are reviewed in this paper. The main families of thermoresponsive polymers, including hydrophilic polymers with LCST (PEG, PNIPAM, poly(oxazoline)s and elastin-like polypeptides, etc.) and hydrophobic polymers with thermotropic phase transitions (liquid crystalline and crystalline polymers), are first described with the details of the underlying physical chemical principles. Polymer colloids with thermoresponsive polymers as the hydrophobic core, hydrophilic corona or both of them depending on temperature (schizophrenic systems) are discussed and their potential bio-related applications highlighted. We also take notice of the particular thermoresponsive properties of PEG in the polymer colloids. Hydrophilic PEG has its water solubility and degree of hydration decreased with increasing temperature in the range far below its LCST (100 °C). These properties can result in significant or even drastic morphological changes in colloids, which should be taken into account when designing thermoresponsive polymer colloids using the PEG corona.