Solution Properties of Polymacromonomers Consisting of Polystyrene. 3. Viscosity Behavior in Cyclohexane and Toluene

Viscosity measurements have been made on two series of polymacromonomer samples consisting only of polystyrene (PS) and having fixed side chain lengths of 15 and 33 styrene residues (designated F15 and F33) in cyclohexane at 34.5 °C (the ϑ temperature) and in toluene at 15 °C (a good solvent). The intrinsic viscosities [η] obtained as functions of (total) weight-average molecular weight M w (in the ranges from 5.1 × 10 3 to 6.5 × 10 6 for the F15 polymer and from 5.4 × 10 4 to 1.1 × 10 7 for the F33 polymer) are analyzed on the basis of the wormlike chain with or without excluded volume. They are described quantitatively by the current theories over the almost entire range of M w studied, when the contribution of side chains near the main-chain ends to the polymacromonomer contour is incorporated into the analysis. The estimated parameters are consistent with those derived previously from gyration radius data, confirming that while the contour length per main-chain residue in the ϑ or good solvent is close to the value expected for the all-trans conformation, the chain stiffness is much higher in the good solvent than in the ϑ solvent due to enhanced monomer−monomer repulsions. The hydrodynamic diameter for each polymacromonomer in cyclohexane, slightly smaller than that in toluene, is about twice as large as the unperturbed end-to-end distance expected for the linear PS molecule having the same degree of polymerization as the side chain.