Polystyrene Size Determination in Polystyrene and Poly(vinyl methyl ether) Using Electronic Excitation Transport

Poly(styrene-co-2-vinylnaphthalene) with a 1.25% fraction of naphthyl fluorophores is studied in two polymeric hosts, polystyrene and poly(vinyl methyl ether). In the polystyrene host, measurement of the electronic excitation transport-induced fluorescence polarization anisotropy decay, r(t), in conjunction with a previous quantitative statistical theory of electronic excitation transport on lightly tagged polymer chains, allows a determination of the copolymer radius of gyration. Comparison with light scattering measurements from the literature establishes the i-condition nature of this solid system. Poly(vinyl methyl ether) forms a compatible polymer blend with polystyrene. Analysis of r(t) data shows that the radius of gyration of a copolymer molecule is expanded in poly(vinyl methyl ether) relative to the i-condition at room temperature. The synthesis of poly(styrene-co-2-vinylnaphthalene) is detailed. I. Introduction Many details of polymer structure and dynamics in polymeric melts and glasses remain unresolved despite the variety of experimental and theoretical techniques that have been applied to their study on both macroscopic and microscopic levels. Since individual polymeric molecules can adopt numerous structural configurations in liquid or solid media, it is necessary to describe polymer properties in a statistical manner. The high density of polymer chain segments within a polymeric solid or melt means that both intramolecular and intermolecular segmental interac- tions are important in determining chain structure. Polymer blends, in addition to their technological importance, are systems that allow the nature of polymer-polymer inter- molecular interactions to be characterized thermodynamically and kinetically. An alternative to the costly development and production of a new polymer is to make mixtures of currently available production polymers to form a blend with the desired properties. However, this process is often thwarted by the presence of small forces between segments of chemically different polymers which leads to macroscopic phase separation. Polymer blending does not result in the large increase in entropy that occurs when two small-molecule liquids are mixed. The connectivity of the polymer segments reduces the number of degrees of freedom within the system and the corresponding favorable increase in the entropy of mixing. Therefore, the components of a potential polymer blend system can have only very minor increases in their enthalpy of mixing if the blend is to be compatible. In some applications, phase separation is beneficial, while in others phase separation is associated with deterioration of desirable material properties. Since the vast