CHAIN DYNAMICS OF POLYISOPRENE CONFINED IN POROUS-MEDIA - A DIELECTRIC-SPECTROSCOPY STUDY

The global dynamics of polyisoprene (PI) in the controlled porous glas s (CPG) Bioran have been studied with dielectric spectroscopy by varyi ng the end-to-end vector ([r(2)](1/2)) of the chain from dimensions sm aller to much larger compared to the pore radius. Pulsed-field gradien t NMR is used for the same systems and shows that all polymer chains a re localized within the pores - no free PI exists. We find that the ef fect of confinement on the length scale of the chain relaxation shows both in the breadth and in the dynamics. In all cases the PI normal mo de within the pores is significantly broadened with respect to bulk PI . The effect on the dynamics was found to depend on the size of the ch ain with respect to the pore radius. Silinization of the CPG has a pro nounced effect on the amplitude and dynamics of the segmental and chai n relaxations.