Solution properties and microstructure of cationic cellulose/sodium dodecyl benzene sulfonate complex system

In this work, the interactions between cationic cellulose (PQ-10) and anionic surfactant (SDBS) in aqueous media were investigated by turbidity, electric conductivity, steady-state fluorescence, shear rheology and transmission electron microscopy (TEM) analyses. Results indicated that precipitation appeared near the charge neutrality point, and the size of precipitation region widened with increasing PQ-10 concentration (0.57–1.72 mM for 0.05% PQ-10, and 2.30–17.22 mM for 0.5% PQ-10). The specific conductivity values of SDBS in the presence of PQ-10 were higher than that of pure SDBS over the whole concentration range under current experimental conditions. The aggregation number of SDBS kept constant in the flat region of the micropolarity curve (0.86 mM–1.43 mM). The structural transformation of the mixtures was monitored visually by TEM. As SDBS concentration increased, the morphologies of the mixtures changed gradually from branched wormlike aggregates to interconnected networks, finally the networks collapsed.

► Network formed in the PQ-10/SDBS system was observed by visual measure (TEM), which has not been reported previously.
► Micropolarity was examined in the whole phase region rather than in a limited region as reported in other literature.
► The relationship between micropolarity and the aggregation number was conducted intensively.