Studies of Poly-2-vinylpyridine. III. Intrinsic Viscosity and Molecular Weight

The viscosity, osmotic pressure and light-scattering of a series of 14 fractions of poly-2-vinylpyridine in various solvents have been measured. The following results have been obtained: The constants, Kw′ and v, in the Mark-Houwink equation have been determined for the solutions of: (a) 92.01 weight per cent ethanol, (b) methanol, (c) dimethylformamide, (d) benzene and (e) dioxane as follows: (a) [η]=1.22×10−4Mw0.73 (d) [η]=1.70×104Mw0.64 (b) [η]=1.13×104Mw0.73 (e) [η]=3.09×104Mw0.58 (c) [η]=147×10−4Mw0.67 The molecular weight of the polymers ranged from 3.4×104 to 93×104, while the viscosity was measured at 25±0.01°C. The constant, K′ in the Mark-Houwink equation in the case of a homogeneous molecular weight has been calculated assuming the exponential- and logarithmic normal-type molecular weight distribution functions for each fraction. The Flory constant, K, defined as [η]θ=KM1⁄2 has been found by the method of Fixman and Krigbaum to be: (8.7±1.0)×10−4 at 25°C. The K value has also been found to be (9.1±1.1)×104 by measuring the intrinsic viscosity in benzene at the θ-point, 16.2°C. The short range interactions of this polymer have also been discussed.