SOLUTION PROPERTIES OF POLY(OCTADECYL METHACRYLATE) IN BUTYL ACETATE .1. DILUTE-SOLUTION

Dilute solutions of poly(octadecyl methacrylate) (PODMA) obtained by radical-initiated polymerization were inverstigated in the theta-solvent butyl acetate (BuAc) by static (SLS) and dynamic light scattering (DLS) and viscometry at six different temperatures between 11-degrees-C (near the theta-temperature THETA and 30-degrees-C. The mass-average molar masses ranged from MBARW = 6,2.10(5) g.mol-1 to 3,2.10(6) g.mol-1. It was found that PODMA in BuAc behaves in general as expected for linear flexible Gaussian coils in a theta-solvent. The Kuhn length was determined to be 35 angstrom. At temperatures slightly above-THETA = 10,5-degrees-C the exponents of the intrinsic viscosity, radius of gyration and hydrodynamic radius versus molar mass relationships lie significantly below 0,5, the expected value for flexible linear chains at theta-conditions. Qualitatively, these findings are explained by a coil contraction due to the different chemical nature of the main chain and the side chains and therefore different polymer-solvent interactions of different parts of the molecules.