The Research Of The Aggregation Behavior Of Shellac-Na In The Aqueous Phase

Shellac,a kind of natural animal resin,was widely used in different fields before petroleum base artificial resin appeared.Entering the new century,with the emergence of the earth's environment pollution and energy crisis,lac resin,a kind of green renewable and biodegradable natural materials once again returned to the sight of people.However,these research were mainly concentrated on the performance of shellac self-assembled materials but no its self-assembled mechanism in the water phase.These could only obtain shellac microspheres but no other self-assembled materials.Hence,the application field was restricted.This work was based on the physical and chemical properties of shellac,the aggregation mechanism of shellac sodium salt in the water phase and the influence factors of aggregation.Moreover,the aggregation mechanism and material properties were characterized,and the factors which effect its performance was explored.We could develop the potential of biological resin,then drive the development of production and the processing of shellac.This study has far-reaching significance in the development of green industry.The main contents were described as follows:?1?Shellac sodium salt was induced by different ion to aggregate the material.The effect of drug loading rate on different drugs was studied in this work.Conclusion:We employed the MALDI-TOF-MS method to determine the molecular distribution of shellac-Na.The peak with the m/z value 1136.78 corresponds to the dimer of shellac-Na which is similar to the asymmetric structure of Gemini surfactants.shellac-Na showed better surface activity.We employed FTIR and DSC to determine the structure change and performance of shellac induced by different ion(Ca²⁺,Na⁺,H⁺).Results showed that we obtained the shellac-Ca,shellac-Na and shellac respectively.It was found that shellac-Na showed higher encapsulated performance to the hydrophobic drug relatively because of the hydrophobic effect.Secondly,shellac-Na showed higher encapsulated performance to the amphiphilic drug compared with hydrophilic drug.?2?Tough.self-assembled natural oligomer hydrogel based on nano-size vesicles cohesion.We employed gluconic acid lactone?GDL?as a slow-release acid to release H⁺ to prepare shellac hydrogels successfully.Moreover,the formation mechanism of gel and its performance were studied in this work.Conclusion: With the hydrolysis of GDL,amphiphilic shellac-Na was transformed into shellac and assembled into the vesicles,Then these vesicles made from shellac-COOH similar to asymmetric gemini surfactants could aggregate together to fabricate the network of the shellac hydrogel by the hydrophobic association between two sets of short hydrophobic chains from two adjacent vesicles.The mechanical properties,moisture content,volume,crystallinity and thermal stability could be adjusted by changing the concentration of shellac-Na,the addition of GDL and the time of forming hydrogel.Shellac hydrogels showed good mechanical properties and degradation,which could be used as the biological foam with high mechanical properties.Therefore,shellac hydrogels showed extensive application prospect.?3?The preparation of shellac hydrogels by using PEG as pore-forming agent.We maded successfully larger aperture shellac hydrogels,and the microstructure and properties were studied in this work.Conclusion: With the increase of the molecular weight and the amount of PEG,the microstructure and aperture of shellac hydrogels had been changed.The pore size of shellac hydrogels increased from 200 nm to 4 microns.We employed FTIR,DSC and TG to analysis hydrogels.The conclusion showed that the addition of polyethylene glycol was not involved in forming shellac hydrogels,just acted as pore-formning agent.