Hydrodynamic behavior of anionically prepared linear polyisoprenes and polystyrenes in carbon tetrachloride

Intrinsic viscosity, [η], weight‐average molecular weight, M w , relationships are reported for narrow molecular weight distribution linear polyisoprene and polystyrene samples in CCl 4 at 25°C. Molecular weight values cover a range nearly two orders in magnitude, extending as low as 3 × 10 3 . In the case of polystyrene there exists a molecular weight range (around M w = 16,700) corresponding to a change in the Mark‐Houwink‐Sakurada (MHS) exponent from α = 0.71 to α = 0.54. Comparisons between the viscometric and hydrodynamic radii, from literature data, are made. For polyisoprene the MHS relationship is reported in CCl 4 , for the first time. For this case α = 0.713 for the whole range of molecular weights studied. Values for the second virial coefficient from low‐angle light‐scattering measurements support the conclusions drawn from viscometry that CCl 4 is a good solvent for both polymers studied. The different behavior of the MHS exponent may be attributed to the difference in chain flexibility.