Physicochemical Properties of 2-Vinylpyridine Telomers Possessing Multihydrocarbon Chains in Aqueous Solution and at the Silica/Aqueous Solution Interface

Physicochemical properties of multialkylated surfactants of partially quaternized 2-vinylpyridine telomers having multihydrocarbon side chains (nRm-2VPQ: n, number of chains; m, alkyl chain length) in aqueous solutions were investigated. The critical micelle concentration (cmc) and surface tension at the cmc were 13 μmol dm−3 and 52 mNm−1 for 2.1R8-2VPQ, 7.1 μmol dm−3 and 37 mNm−1 for 2.5R12-2VPQ, and 4.7 μmol dm−3 and 40.0 mNm−1 for 3.4R12-2VPQ, respectively. The aggregation numbers at the cmc determined by the light scattering method were 4 ± 1 for 2.1R8-2VPQ, 45 ± 10 for 2.5R12-2VPQ, and 11 ± 1 for 3.4R12-2VPQ. Thus, the number of chains and the alkyl chain length of the telomers affected the micellar properties in aqueous solutions. At the interface of the silica/aqueous solution, the adsorbed amounts of the telomers increased sharply at their low concentrations and reached a plateau by forming a monolayer and a subsequent bilayer. Silica suspensions also showed a dispersion–flocculation–redispersion sequence with the telomer concentration, where the maximum sedimentation rate was influenced by the number of chains and the alkyl chain length of the telomers.