Dilute Solution Properties of Monodisperse Poly(α-methyl styrene). I. Sedimentation Coefficient in Theta Solvent

The sedimentation behavior of anionically polymerized poly (α-methyl styrene) has been studied as a function of molecular weight, concentration and speed of centrifugation under the theta condition of solvent and temperature, i. e., in cyclohexane at 39°C. Analysis of the data was made by use of Fujita’s equation for the pressure- and concentration-dependent sedimentation. It was found that the sedimentation coefficient at zero concentration and one atmosphere was given as s00=2.00×10−15 M1⁄2 sec, where M is molecular weight. The concentration dependence coefficient k and the pressure dependence coefficient p appearing in the Fujita equation were obtained as k=6.2×10−4 M1⁄2 dl/g, and μ=1.6×10−9 cm2/dyne, respectively. The intrinsic viscosity in the theta solvent was also determined as [η]θ=7.60×10−4 M1⁄2 dl/g.