Synthesis, temperature gradient interaction chromatography, and rheology of entangled styrene comb polymers

We present the synthesis of polystyrene combs via an improved procedure, which allows the average number of arms to be small (3-5) but well controlled. It is shown that temperature gradient interaction chromatography (TGIC) proves to be a highly effective method for the analysis of these combs, providing directly the distribution of the number of arms on the synthesized comb molecules. We use this arm-number distribution to model the linear rheology of an entangled melt of such combs, via our previously published algorithm [Das et al. J. Rheol. 2006, 50, 207-234], and demonstrate that this compares favorably with the measured linear rheology. A comparison is also made with the predicted rheology for two alternative assumptions about the distribution of arms on the comb, (i) where it is assumed that the addition of arms is an ideal random process and (ii) where there is a fixed number of arms per comb. These predictions also agree well with the experimental results, thus supporting the validity of simpler analytical approaches based on constant arm number, at least for the arm-number distribution considered here.