Kosmotropic effect leads to LCST decrease in thermoresponsive polymer solutions

摘要

We study the phenomena of decrease in lower critical solution temperature(LCST) with addition of kosmotropic (order-making) cosolvents inthermoresponsive polymer solutions. A combination of explicit solventcoarse-grained simulations and mean-field theory has been employed. Thepolymer-solvent LCST behavior in the theoretical models have been incorporatedthrough the Kolomeisky-Widom solvophobic potential. Our results illustrate howthe decrease in the LCST can be achieved by the reduction in the bulk solventenergy with addition of cosolvent. It is shown that this effect of cosolvent isweaker with increase in polymer hydrophilicity which can explain the absence ofLCST decrease in PDEA, water and methanol systems. The coarse-grained nature ofthe models indicates that a mean energetic representation of the system issufficient to understand the phenomena of LCST decrease.