Study On The Synthesis And Viscoelastic Solutions Of Rosin-based Surfactants

With the development of science and technology,the research of new"green"surfactants with excellent properties has become one of the important topics in the surfactant fields.Rosin is one of the natural products.When reacted with the amino acids and glucose,it is expected to produce a series of new biodegradable rosin-based amino acid surfactants with excellent properties and a wide range of applications,in line with the concept of green chemistry and sustainable development.At the same time,it is helpful to reveal the law of self-assembly behavior of surfactants by changing the molecular structure and exploring the influence of intermolecular interaction on the self-assembly behavior.In this thesis,the dehydroabietic acid,various amino acids and glucose were taken as the starting material.Two series of rosin-based surfactants were successfully synthesized,and their self-assembly properties were studied.The main contents are summarized as follows:?1?Using dehydroabietic acid and various amino acids as raw materials,three rosin-based amino acid surfactants,abbreviated R-6-Ala,R-6-Ser and R-2-2-Ser,were synthesized.The du Noy ring method and fluorescence probe method were used to investigate the surface activities.At 25°C,the cmc values are 4.59 mmol·L^-1,0.38 mmol·L^-1 and 2.00mmol·L^-1,respectively,indicating that the introduction of hydroxyl groups in the molecular structure is beneficial to enhance the intermolecular hydrogen bonding,so that the surfactant is more likely to aggregate to form micelles,and the introduction of amide groups into the intermediate carbon chain structure weakens the hydrophobic interaction,making the molecules less likely to aggregate inside the solution.Besides,these surfactants all show good emulsifying properties and foam stability.?2?The viscoelastic properties and microscopic of aggregates of R-6-Ser/?-CD and R-2-2-Ser/CTAB systems have been investigated by rheology,SAXS,Cryo-TEM,CD and ¹H NMR.R-6-Ser and?-CD form fiber aggregates?about 7-8 nm cross-sectional diameter?with right-handed helix characteristics in aqueous solution under the synergistic interaction of host-guest interaction,hydrophobic interaction and hydrogen bonding;R-2-2-Ser and CTAB formed wormlike micelles with good viscoelasticity through electrostatic interaction.And with the increase of concentration,various forms of wormllike micelles are formed in the system,which is attributed to the skeleton effect of the rigid group.?3?Using dehydroabietic acid and glucose as raw materials,two kinds of rosin-based glucose surfactants R-6-Glu and R-8-Glu were synthesized.The du Noy ring method and fluorescence probe method were used to investigate the surface activities.At 25°C,the cmc values are 1.30 mmol·L^-1 and 1.31 mmol·L^-1,respectively,indicating that the small change in the length of the intermediate carbon chain of the surfactant has little effect on the aggregation ability.And R-6-Glu and R-8-Glu have good emulsifying properties and foam stability.The foam stability of R-8-Glu is obviously better than that of R-6-Glu at the same concentration,which reveals that the change of molecular structure has an important effect on the properties of surfactants.?4?The viscoelastic properties and microscopic of morphology of R-8-Glu systems have been investigated by rheology,Cryo-TEM and CD.At low concentrations,R-8-Glu forms a considerable amount of spherical micelles in aqueous solution.While at high concentrations,R-8-Glu without any additives forms wormlike micelles with chirality through hydrogen bonding and hydrophobic interactions,endowing the systems with an good viscoelasticity.This provides a new way to prepare novel viscoelastic systems.