Solution and rheological properties of cationic cellulose/gemini surfactant: Effect of the alkyl chain and spacer length

In this paper, three sulfonate-containing gemini surfactants, sodium 1,1'-(4,4'-methylenebis(4,1-phenylene))bis (1-oxooctane-2-sulfonate) (C-8-M-1-C-8), sodium 1,1'-(4,4'-(ethane-1,2-diyebis(4,1-phenylene))bis(1-oxooctane-2-sulfonate) (C-8-M-2-C-8), sodium 1,1'-(4,4'-methylenebis(4,1-phenylene))-bis(1-oxododecane-2-sulfonate) (C-12-M-2-C-12), were synthesized and characterized with FT-IR, H-1 NMR and MS. Furthermore, interaction between a cationic cellulose-based polyelectrolyte, PQ-10, and gemini surfactants were investigated by surface tension, turbidity, flow and low-amplitude oscillation rheology analysis. For comparing, the interaction of their corresponding monomeric counterpart sodium dodecyl sulfate (SDS), sodium 1-octanesulfate (SOS) was also studied. Results showed that the concentration value at T-1, defined as critical surface complex concentration, for the PQ-10/surfactant was in order of PQ-10/C-8-M-2-C-8 > PQ-10/C-8-M-1-C-8 > PQ-10/C-12-M-2-C-12. Precipitation appeared at low concentration for Gemini surfactants than their monomeric counterparts, and for the gemini surfactants with shorter spacer or longer hydrocarbon chain. The increase/decrease of the crossover frequency (omega(c)) (the relaxation time, tau(c)) for PQ-10/C-12-M-2-C-12 indicated the formation/collapse of network structures, while PQ-10/SDS showed no obvious change.