Novel Rosin-based Surfactant:The Effect Of The Rigid Hydrophobic Structure On Its Self-organization Behavior

Rosin is one of renewable and biodegradable natural resources. It is also the important raw materials of green surfactants because the structure of which can be easily modified. Dehydroabietic acid is one of the important rosin derivatives with stable chemical properties. In this thesis, the traditional purification method of dehydroabietic acid from disproportionated rosin amine salt has been improved. Two types of rosin-based surfactants have been synthesized. Their surface activity, emulsion ability and rheological properties of solutions have been investigated. The rigid structure of dehydroabietic acid skeleton on the self-assembly of these novel surfactants has been focused. The main results are summarized as follows:(1) The traditional purification method of dehydroabietic acid has been optimized. Three factors that affect the purity and the yield of dehydroabietic acid have been concerned. The first factor is the molar ratio of ethanolamine and disproportionated rosin in synthesizing the amine salt of dehydroabietic acid. The second factor is the volume ratio of ethanol and petroleum ether in solubilizing the amine salt. The third factor is the recrystallization technology. The results give out the optimal conditions. The molar ratio of ethanolamine and disproportionated rosin is 0.8. The volume ratio of ethanol and petroleum ether is 1:10. The amine salt is recrystallized twice. The obtained dehydroabietic acid has been characterized with mass spectrum and gas chromatography. The purity of the dehydroabietic acid can reach to 97.4% and the yield is 30.2%.(2) Three novel rosin-based Gemini surfactants 1, 6-bis(3-Dehydroabietic amide-propyl-dimethyl ammonium bromide)hexane, 1, 8-bis(3-Dehydroabietic amide-propyl-dimethyl ammonium bromide)octane and 1, 10-bis(3-Dehydroabietic amide-propyl-dimethyl ammonium bromide)decane(abbreviated as R-6-R, R-8-R and R-10-R), have been synthesized from dehydroabietic acid via reactions of amidation and quaternization. The chemical structures and the purity of the intermediate and final products were all identified by 1H NMR and mass spectrum. The results show that the series of surfactants has good water solubility and surface activity, and the critical micelle concentration of R-6-R, R-8-R and R-10-R is 0.41 mmol/L, 0.39 mmol/L and 0.24 mmol/L, respectively. The foaming and emulsifying properties of these compounds were also excellent. The reason is attributed to the rigid hydrophobic group contained in the rosin-based Gemini surfactants. The high elastic adsorption film formed at the interface has a stronger ability to stabilize emulsions and foams.(3) A rosin-based amino acid surfactant sodium 11-dehydroabietamidoundecanoate(abbreviated to R-11), has been synthesized from dehydroabietic acid and 11-aminoundecanoic acid via reactions of acyl chlorination and amidation. The chemical structures and the purity of the products were identified by 1HNMR. The surface activities of R-11 and R-11/bi-N(n)-Br(n=8, 10, 12) have been investigated. Compared with the sodium dehydroabietate, the aggregation ability of R-11 was stronger because of the introduction of a flexible alkyl chain. The aggregation ability of R-11 was further enhanced with the addition of bi-N(n)-Br(n=8, 10, 12), a dimeric quaternary ammonium salt. The critical micelle concentration was also influenced by the spacer length of bi-N(n)-Br(n=8, 10, 12). The rheological measurements show that R-11 can form good viscoelastic solutions with the addition of the dimeric salts. The reason is attributed to the large hydrophobic group volume of the dehydroabietic acid skeleton. The system viscoelasticity becomes better when the spacer length of the dimeric salt is shorter. R-11/bi-N(8)-Br system shows the best performance. The zero shear viscosity can reach to 1×103 Pa·s. The investigation of the present systems is expected to expand the applications of rosin based surfactants.