Polymers and copolymers obtained from the polymerization of substituted phenylacetylenes, namely PMOPPA and copolymers PPA/PMOPPA, PMOPPA/PNPPA, PPA/PNPPA, have been characterized by means of dynamic light scattering and UV-Vis absorption measurements. The analysis of the light intensity correlation function shows a similar behaviour for all the systems investigated, with three decay modes correlated to the molecular structures. The steric hyndrance and the electron polarization modify the hydrodynamic radius of the polymers and cause polymer/solvent interactions, whose strength depends on the solvent. The polymers structure does not change appreciably during the time lasting for the experiments, as assessed by UV-Vis optical tests. (C) 2003 Elsevier Science B.V. All rights reserved.