Study On The Synthesis And Properties Of Rosin-based Ionic Surfactants

The development and utilization of biomass resources bears substantial significance to promote the harmonious development between human and nature.Surfactants have a wide applications in many aspects of daily life and industrial production.Preparing new surfactants taking biomass resources as raw materials has become increasingly attractive.In this paper,dehydroabietic acid,which was purified from disproportionated rosin,was used as the raw material to synthesize surfactants.Two rosin-based ionic surfactants have been successfully prepared,the self-assembly of which has been investigated.The main contents are summarized as follows:1.Taking the dehydroabietic acid as the starting material,a rosin-based quaternary ammonium cationic surfactant,abbreviated R-6-N,was synthesized through a series of reactions.The structure and purity of the intermediates and the final product were identified by ¹H NMR and high resolution mass spectrometry?HRMS?.2.Surface tension method,fluorescent probe method and conductivity method were used to investigate the surface activities of R-6-N.The results showed that cmc,?_cmc and cmc/C₂₀ of R-6-N were 4.43 mmol·L^-1,34.56 mN·m^-1 and 6.82,respectively.Besides,R-6-N has strong abilities in stabilizing emulsions.The dynamic surface tension?DST?results of R-6-N showed that,due to the large volume of rigid structure contained in the R-6-N molecule,a large activation barrier(Ea=22.8 kJ·mol^-1)presented during the adsorption process.3.A rosin-based anionic surfactant?R-11-2-Na?,which contains a large hydrophobic group of 30 carbon atoms,has been synthesized taking dehydroabietic acid,11-aminoundecyl acid and glycine as the starting materials.The structure of R-11-2-Na has been identified with ¹H NMR and high resolution mass spectrum?HRMS?.The surface activity of R-11-2-Na was investigated by surface tension method and fluorescent probe method.The cmc value of R-11-2-Na is 0.23 mmol·L^-1,which indicated that R-11-2-Na has excellent aggregation ability.R-11-2-Na has a strong stability to stabilize emulsions and foams.The n-decane/water emulsion stabilized by 0.3 mmol·L^-1 R-11-2-Na remained stable more than 6 months,and the half-life t_1/2 of foam formed by R-11-2-Na aqueous solution was as long as 1504 min.4.The solutions with strong viscoelasticity can be obtained by adding organic salt choline chloride?ChCl?to an aqueous solution of R-11-2-Na.The viscoelastic solutions have been investigated using rheology,small-angle X-ray scattering?SAXS?,and freeze-fracture transmission electron microscopy?FF-TEM?methods at 25°C.Due to the strong van der Waals interactions caused by the large hydrophobic group contained in R-11-2-Na,the zero-shear viscosity??₀?of solutions showed extremely strong dependence on the concentration with an exponent of 23.4.The cross-sectional diameter of the wormlike micelles?²0 nm?in the present system was significantly larger than that of the wormlike micelles formed by surfactants containing conventional alkyl tails.This finding may be attributed to the steric hindrance brought by the bulky and rigid dehydroabietic acid unit in the hydrophobic part.The results reveal that the rigid structural unit of rosin plays a unique role in the self-assembly process of surfactants,which promotes the application of rosin resources in the field of complex fluids.