The role of solvation on the conformational change during repeated freezing–thawing treatment to an extremely dilute aqueous solution of poly(vinyl alcohol)

The effect of solvation–desolvation process on the conformational change of poly(vinyl alcohol) in an extremely dilute aqueous solution during the repeated freezing–thawing treatment was investigated by a differential refractometer. It was found that the hydrodynamic volume of PVA decreased regularly and smoothly with the number of freezing–thawing cycles treatment increasing, as the intra-molecular entanglement points made the polymer chain contract, and even in a full compacted globule state, there were still some solvent molecules in the chain. The extraordinary phenomenon was successfully explained and treated by a quantitative theory in terms of accompanying solvation–desolvation process during the macromolecular chain having contracted.