Association of Amino-Terminated Polystyrenes. 3. Trifunctional Star Polymers

Abstract

Amino-terminated three-armed polystyrene stars of narrow molecular weight distribution were prepared by anionic polymerization. The association of these star polymers with a low molecular weight dinitrophenol compound was studied by means of light scattering and ultraviolet-visible spectroscopy in the good solvent 1,4-dioxane and in the Θ solvent diethyl malonate. The concentration dependence of the scattered intensity was used to derive the increase in weight average molecular weights of the associates Mw(c) where a correction was applied that allowed the separation of the influence of repulsion forces. The experimental molecular weights were found to be smaller than predicted by the Flory-Stockmayer branching theory. Deviations are stronger for star polymers of low molecular weight, which is explained by intramolecular complex formation. No substantial difference was detected between the association in good and Θ solvents. Gel formation did not occur, and reasons are discussed.

Association of Hydrophobically End-Capped Poly(ethylene oxide)

“…The difficulty is to correctly incorporate interactions. At low concentrations one could use estimates of the second and third virial coefficient for branched polymers as was done in ref . However, this procedure is obviously incorrect at concentrations above C *, and furthermore it is not clear how one can quantify the effect of increasing polydispersity on the virial coefficients.…”

Association of Telechelic Ionomers in Apolar Solvents

“…Estimates of the second and third virial coefficient for branched polymers could be used. [59] However, this procedure is valuable only in a relatively dilute range of concentrations and is obviously inappropriate above C*. Moreover, we cannot quantify the effect of increasing polydispersity on the virial coefficients.…”