Static and dynamical properties, in terms of polymer dimensions, such as the radius of gyration (γg) and the hydrodynamic radius (γh), and intermolecular interactions, such as the second virial coefficients (A2, kD, k(), of a high molecular weight polystyrene (Mw = 1.2 × 107) in trans-decalin in the dilute solution region have been investigated. We present quantitative experimental data on the temperature IT) and some molecular weight (Mw) dependence of rh and (γg2)z1/2 over the transition region before the asymptotic simple power laws become valid. In the excluded volume regime for very large polymer coils dissolved in a good solvent, the blob theory of chain statistics is in very good agreement with experiments. Our data should provide experimental boundary conditions for the modification of the blob theory, even though such changes are likely to destroy the discontinuous jump from the Gaussian to the excluded volume behavior in the blob model. We also present experimental data on the contraction of polymer coils and interaction changes below the θ temperature. Collapse of polymer coils is of interest and requires further study. © 1979, American Chemical Society. All rights reserved.