HETEROGENEOUS CATALYTIC-HYDROGENATION OF POLY(STYRENE) - THERMODYNAMICS OF POLY(VINYLCYCLOHEXANE) CONTAINING DIBLOCK COPOLYMERS

Heterogeneous catalytic hydrogenation of 1,4-poly(isoprene) (PI), atac tic poly(styrene) (PS), and two poly(styrene)-poly(isoprene) (PS-PI) d iblock copolymers was performed using two palladium supported catalyst s. In each case fully saturated materials were obtained with no chain degradation. The dynamic and thermodynamic properties of these materia ls were investigated using differential scanning calorimetry and dynam ic mechanical spectroscopy. Saturated poly(styrene), denoted poly(viny lcyclohexane) (PVCH), exhibited a glass transition temperature (T(g)) that is 40 deg higher than that of poly(styrene). For diblock copolyme rs of PVCH and poly(ethylene-propylene) (PEP) this increase in T(g) is accompanied by a slight increase in the order-disorder transition tem perature, T(ODT), relative to that characterizing the PS-PI precursor. Estimates of the associated segment-segment interaction parameters ba sed on group contribution methods anticipate a steep reduction in T(OD T) with saturation, contrary to this result.