Reversibility of thermodynamic lower critical solution temperature phenomenon in miscible poly(epsilon-caprolactone)/poly(benzyl methacrylate)

Differential scanning calorimetry and optical microscopy were performed to examine the reversibility of phase separation at above the lower critical s olution temperatures in a miscible poly(epsilon-caprolactone) (PCL)/poly(be nzyl methacrylate) (PBzMA) blend system. Upon heating, phase separation occ urred via a binodal nucleation and growth (NG) mechanism at above 240 degre es C, which is a lower critical solution temperature (LCST). The pattern of phase domains suggests that the phase separation was meta-stable. Interest ingly, the LCST phase separation was found to be readily reversible to orig inal homogeneity upon cooling at regularly accessible rates. A major factor may be that the temperature window between the LCST curve and blend T-g cu rve is wide, resulting in a convenient temperature range for the polymer ch ains to kinetically reorganize to a state favored by the thermodynamic cond itions.