HYDRODYNAMIC BEHAVIOR OF ANIONICALLY PREPARED LINEAR POLYISOPRENES AND POLYSTYRENES IN CARBON-TETRACHLORIDE

Intrinsic viscosity, [eta] weight average molecular weight, M omega, r elationships are reported for narrow molecular weight distribution lin ear polyisoprene and polystyrene samples in CCI4 at 25 degrees C. Mole cular weight values cover a range nearly two orders in magnitude, exte nding as low as 3 X 10(3). In the case of polystyrene there exists a m olecular weight range (around M omega = 16,700) corresponding to a cha nge in the Mark-Houwink-Sakurada (MHS) exponent from alpha = 0.71 to a lpha = 0.54. Comparisons between the viscometric and hydrodynamic radi i, from literature data, are made. For polyisoprene the MI-IS relation ship is reported in CCl4, for the first time. For this case alpha = 0. 713 for the whole range of molecular weights studied. Values for the s econd virial coefficient from low-angle light-scattering measurements support the conclusions drawn from viscometry that CCl4 is a good solv ent for both polymers studied. The different behavior of the MHS expon ent may be attributed to the difference in chain flexibility. (C) 1995 John Wiley & Sons, Inc.