A novel bio-based anionic surfactant containing a large rigid group and a flexible alkyl chain, namely, sodium N-dodecyl-maleimidepimaric carboxylate (C-MPA-Na), was synthesized from rosin. The molecular structure of C-MPA-Na was identified using H NMR, FT-IR spectroscopy and MS. Despite containing 36 carbon atoms, C-MPA-Na showed good water solubility at room temperature. Large spherical aggregates with diameters of 100-200 nm were formed by C-MPA-Na when its concentration was above 0.1 mM, which was slightly higher than the critical micelle concentration (0.078 mM). Annular wormlike micelles were discovered with increasing C-MPA-Na concentration, and began to change into extremely long threadlike wormlike micelles when the C-MPA-Na concentration reached approximately 58 mM. The viscoelastic properties of the wormlike micelle solutions were investigated using steady state and oscillatory shear sweep rheological measurements. The zero-shear viscosity (η) strongly depended on the concentration of C-MPA-Na, and the scaling exponent was 34.1. Cryo-TEM confirmed the formation of large spherical aggregates and wormlike micelles. H-H 2D nuclear Overhauser effect spectroscopy (NOESY) was used to detect the molecular interactions of C-MPA-Na. The results indicated that the alkyl chain of C-MPA-Na was partially overlapped with its non-planar rigid structure in aqueous solution, and the possible aggregation process for C-MPA-Na was proposed.

A novel pH-responsive wormlike micellar viscoelastic solution was constructed by a rosin-based anionic surfactant (Na-MPA-AZO-Na) in the presence of cetyltrimethylammonium bromide (CTAB). The viscoelasticity, aggregate morphology, and pH-responsiveness of the pH-responsive wormlike micelles have been investigated through the method of rheology and cryogenictransmission electron microscopy. Its corresponding mechanism has been studied using 1 H NMR and 1 H− 1 H 2D NOESY HNMR. The zero-shear viscosity (η 0 ) of the wormlike micellar solution rapidly decreases by 3 orders of magnitude as the pH increases from 5.21 to 9.56. The viscoelastic fluids and water-like solutions can be converted by tuning the pH between 3.62 and 12.00, and the corresponding aggregates also transform between wormlike micelles and spherical micelles. In addition, the wormlike micellar crosssectional diameter is approximately 10 nm, which is remarkably larger than that of the common wormlike micelles. The phenomenon can be attributed to the large steric volume of the rosin rigid skeleton. When the pH is 12.00, a "pseudo" Gemini surfactant is constructed by Na-MPA-AZO-Na and CTAB through the electrostatic interactions. Wormlike micelles also can be formed with the increasing concentrations. The η 0 of the wormlike micellar system shows strong dependence on concentration with an exponent of 9.6 (η 0 ∝ C 9.6 ). This work further promotes new applications of forest resources.