CONFORMATION OF STAR POLYMERS IN HIGH-MOLECULAR-WEIGHT SOLVENTS

Ten years ago Daoud and Cotton proposed a very elegant model for the static properties of an isolated star-shaped polymer in a solvent of low molecular weight. Here we investigate the static behavior of a star-shaped polymer (f arms; N monomers per arm) dissolved in a melt of linear chains (with degree of polymerization P < N), chemically identical to the star arms. We predict that the N-monomer volume fraction varies as phi(N)(r) congruent-to 1 (meltlike region) for r < af1/2P1/4 and phi(N)(r) congruent-to (r/a)-4/3f/2/3P1/3 for r > af1/2P1/4. We briefly discuss concentration effects. In addition to this analysis, we also review and discuss some of the properties of polymer chains tethered by one end to a flat solid surface. Our whole study is restricted to scaling laws; the exact prefactors in all our formulas remain undetermined.