Molecular Strand Dynamics And Gel Stability Of Glucomannan

Glucomannan is an excellent water-soluble non-ionic polysaccharide polymer,which is a abundant source having very excellent gelling properties.Combined with its exeellent characteristies,for example,water retention property,water absorption and biocompatibility and so on,Konjac Glucomannan(referred to KGM the following)hydrogel,becomes a new type of polymer functional materials,widely applied in various areas such as smart hydrogels,structured hydrogel,rapid response hydrogels,physically crosslinked hydrogels,interpenetrating network hydrogels and so on.But the application of KGM hydrogel did not go well,finding that the strength and flexibility of gel is unstable,dehydration and so on.Since the variation of structural characteristics underly cause the change of functional properties,to make the application of KGM hydrogel better,we need to study the molecular network structure of KGM,revealing the factors that affect the structural stability of KGM hydrogel.Based on the molecular structure of KGM in this paper,by molecular simulations(Molecular Dynamics simulations,Dissipative Particle Dynamics simulation,the following launchs research on gel formation process of KGM and Carrageenan?KGM and Borax and when an acetyl content in a different case,the physical state of KGM,recording the reactions of its interaction situations.In order to obtain KGM gel which is most stable and has the lowest energy,this paper explores the mechanism of gel formation and influencing factors of stability of KGM gel.The main contents and results are as follows:(1)Taking advantage of mesoscopic simulation method,by DPD module of Material Studio software,simulate the interaction processes of KGM and Carrageenan forming complex gel.On the level of mesoscopic aggregation state,study the compound mechanism of synergies of KGM and Carrageenan.Changes in energy from the complex gel,changes in mesoscopic morphology from the complex gel,changes of value from the end of the gel,changes in interfacial stress from the complex gel,showed that the compounding of KGM and carrageenan can play roles,such as gel strength and viscosity has been enhanced etc,which are consistent with previous experimental studies.Studies have shown that,the molecular chain entanglement of the compounding gel of KGM and carrageenan may have become coupling entanglement in the gel state from the simple hydrogen bonding,van der Waals interaction in aqueous solutions.With the increasing of compounding concentration of KGM and carrageenan,molecular chain tangles more closely,a tendency to topology entanglement.(2)Using the mesoscopic simulation method,by DPD module of Material Studio software,simulate the interaction processes of KGM and Borax forming gel in aqueous solutions.By focusing on Dissipative Particle Dynamics simulation shows the process of changes of mesoscopic morphology of gel dynamically and vividly with the increasing of the number of simulation steps of composites.Through the changes in the energy of complex gel,the changes in the interface stress of complex gel,analyze the microscopic reasons for the changes of macroscopic properties,such as the strength of KGM-Borax composites gel become stronger than KGM gel,the syneresis rates of KGM-Borax composites gel become lower.Studies have shown that,the interfacial stress of KGM-Borax composites gel become stronger than KGM gel.With the gradual increase of volume fraction of KGM-Borax composites,mesoscopic morphologies of forming gel become quite different,mainly the gap between micelles from the larger to seamless.KGM-Borax composites gel mainly form through the micelles of KGM tightly wounding around the surrounding the aggregation of Borax molecular chains whose micelles is the core of gel.As increases of the volume fraction,micelles grow,increase and wound around together to form gel.(3)By Dissipative Particle Dynamics simulation,shows the process of changes of mesoscopic morphology of gel from different degree of deacetylation or different degree of acetylation of KGM in aqueous solution.Drawing the following conclusions:when the acetyl content is less than the acetyl content of the natural KGM about 70%,with acetyl content becomes less,solubility of KGM molecular becomes lower,KGM gel forming in the end.When the acetyl content is more than the acetyl content of the natural KGM about 1.5 Times,with acetyl content becomes larger,KGM gel becomes more.Analyzing the results of Mesoscopic morphology changes and the time of reach equilibrium on the analog system in the KGM gel,Speculate that the presence of an acetyl group has a great influence on the solubility of KGM.When acetyl group content is within a certain range,KGM has high solubility,but out the eertain range,the solubility of KGM showed a downward trend.High hydrophilicity and non-hydrophobic neutral polysaccharide KGM,when adding alkali deacetylation,acetyl content decreased rapidly and steric effects produced from the acetyl greatly reduced.KGM molecular chain keep associative via hydrogen bond from intramolecular and intermolecular or van der Waals forces.B surface of glucose and mannose hydrophobic heap together constantly,form a hydrophobic microdomains.When hydrogen bond,hydrophobic interaction have greatly enhanced,KGM irreversible gel when heated form in a short.