Polymers with upper critical solution temperature behavior in alcohol/water solvent mixtures

Thermoresponsive polymers are of great importance in numerous nanotechnological and biomedical applications. Compared to polymers that undergo a lower critical solution temperature (LCST) phase transition in aqueous solution, i.e., demixing occurs upon heating, polymers exhibiting the reversed upper critical solution temperature (UCST) behavior in aqueous solution have been much less documented as it is more challenging to achieve this behavior in aqueous solutions. Furthermore, the high sensitivity of UCST behavior to minor variation in polymer structure and solution composition hampered the development of applications based on these polymers [18]. However, polymers with UCST transition in alcohol/water solvent mixtures are more commonly reported and exhibit promising properties for the preparation of 'smart' materials. This review will focus on the theory and development of such polymers with UCST behavior in alcohol/water solvent mixtures. By highlighting reported examples of UCST polymers in alcohol/water solvent mixtures, we aim to demonstrate the versatility and potential that such UCST polymers possess as biomedical and 'smart' materials.