Time-resolved optical spectroscopy study of the local dynamics of cis-1,4 and vinyl-1,2-polybutadiene in dilute solution at high pressure

The local segmental dynamics of anthracene labelled cis-1,4-polybutadiene in dilute solution and vinyl-1,2-polybutadiene in dilute solution have been studied by means of time-resolved optical spectroscopy as a function of temperature (298–323 K) and pressure (0.1–150 MPa) in several solvents (dioctyl phthalate, squalane, cis-decalin, n-dodecane and toluene) of good thermodynamic quality. This range of temperatures and pressures afforded a viscosity range of three decades. Kramersʹ theory predicts local motions that scale as the first power of the steady shear solvent viscosity. However, findings from this study reveal motions that scale as the 0.61±0.03 power of the solvent viscosity for cis-1,4-polybutadiene and 0.75±0.04 for vinyl-1,2-polybutadiene over the entire pressure and temperature range.