ULTRAFAST SIDE GROUP MOTIONS OF POLYMERS

The local dynamics of poly(2-vinylnaphthalene) (P2VN) have been investigated using femtosecond transient grating optical Kerr effect measurements. In solid P2VN, a single exponential 140-fs decay is observed. This decay is attributed to librational relaxation of the naphthyl side groups. In P2VN/CCl4 solution, besides the librational decay, there exist two slower orientational relaxation components. These decays are temperature independent in the range -3 to +55-degrees-C, although the bulk sheer viscosity of the solution and the viscosity of pure CCl4 change considerably. This is in contrast to the orientational relaxation of 2-ethylnaphthalene in CCl4 solution which displays a conventional (hydrodynamic) temperature dependence. The measurements on P2VN solid and solutions are discussed in terms of the local environments of the naphthyl side groups.