Association of adhesive spheres formed by hydrophobically end-capped PEO. 2. Influence of the alkyl end-group length and the chain backbone architecture

We studied the effect of the length of alkyl end groups and chain backbone architecture on the associative properties of end-capped PEO. The latter was done by comparing linear and star PEO with the same hydrophilic-lypophilic balance. With increasing length of the end groups the association number (p) of the polymeric micelles increases and the critical association concentration decreases, but these parameters are not influenced by the chain backbone architecture. The polymeric micelles behave as adhesive spheres if p is sufficiently large, which explains the phase behavior and the light scattering results. The critical concentration where the spheres percolate varies little with the length of the end groups and the architecture. At a given concentration the viscosity increases with increasing length of the end groups because the lifetime of the end groups in the multiplet increases. The chain backbone architecture has little influence on the viscoelastic properties.