The Interactions Between Cationic Cellulose And Single-chain/Gemini Sulfnate Surfactants

In this paper, the interactions between cationic cellulose and anionic surfactantswere studied by turbidimetric titration, surface tension, electric conductivity,fluorescence, rheology and transmission electron microscopy （TEM）. The aggregationproperties, microstructure and the phase behavior of cationic cellulose/sodiumdodecyl benzene sulfonate （SDBS） system were investigated. And the interactionsbetween cationic cellulose and sulfonate Gemini surfactant versus its single-chaincounterpart were examined. Based on these results the applications of cationiccellulose/anionic surfactant system in drug release and dispersion of carbon nanotubeswere further researched. The details were as follows:1. A correlation between the micropolarity and the aggregation number ofcationic cellulose （H-PQ-10or L-PQ-10）/SDBS system was established by fluoresce-ence. The aggregation number maintained growth as the micropolarity decreased andkept constant when the micropolarity remained invariant. It was suggesting that thehydrpohobicity of micelle-like aggregates enhanced with increasing of their size,which resulted in the decrease of the micropolarity of the complex solution.2. The microstructures of H-PQ-10or L-PQ-10/SDBS system were observed byrheology and TEM. Results indicated that the variation of the structure of the complexwith surfactant concentration could be divided into three regions （critical points werefrom curves of η₀～C and τ～C, C₁（C₁’） corresponded to the critical concentration atwhich η₀（τ） began to increase sharply with increasing SDBS concentration, C₂（C₂’）corresponded to the SDBS concentratrion where η₀（τ） attained maximum value）.When C <C₁（C₁’）, only few polymer chains were bound together by SDBS micelles,no network formed and the motion of polymer chains was not confined by surfactantmicelles. When C₁（C₁’）<C <C₂（C₂’）, network structures formed and became perfectprogressively. When C> C₂（C₂’）, the network collapsed.3. All the three Gemini surfactants （8Ph-1-Ph8,8Ph-2-Ph8and12Ph-1-Ph12）interacted strongly with H-PQ-10as compared to their single-chain counterparts,sodium1-octanesulfonate （OAS） and sodium dodecyl sulfonate （SDS）. Results alsorevealed that the interaction was enhanced by increasing the hydrocarbon chain lengthor decreasing the spacer length of surfactant.4. The probenazole release of H-PQ-10/SLS microcapsule followed zero-order release kinetics. When the C+/C-ratio of the H-PQ-10/SLS system was9:13, therelease rate of probenazole was lowest and the cumulative release of probenazole washighest.5. H-PQ-10/12Ph-1-Ph12complex system had good dispersion ability to carbonnanotubes as compared to polymer or surfactant alone. It was also indicated that thedispersion effect of H-PQ-10/surfactant system to carbon nanotubes improved withincreasing the hydrophobicity of surfactant.