Research On Characteristics Of Konjac Glucomannan-Fluorescent Dropout Complexes

This paper attempted to use konjac glucomannan molecule as based structure,through the molecular simulation software and the molecular interactions in konjac glucomannan system,konjac glucomannan-tyramine sysytem,konjac glucomannan-tyramine-fluorescein isothiocyanate system,obtained the optimal experimental conditions and a the lowest steady energy state of the konjac glucomannan fluorescent combined substance.By observing the changes of mesoscopic morphology,interfacial tension,diffusion coefficient,the method of spectroscopy and other changes of konjac glucomannan system and konjac glucomannan-fluorescent system,it discussed the reasons of changes in molecular structure,the combined rate and the rheological combination characteristics of konjac glucomannan and fluorescent material.The main research contents and results were as follows:The results showed that:1.The method of molecular dynamics simulations in konjac glucomannan-tyramine system was used to studied the interactions between konjac glucomannan and tyramine from the microcosmic level perspective,and it showed that:(1)the tyramine and konjac glucomannan could be combined to form a stable system under the influence of NaBH4.Because of the sodium borohydride,which was caused by the complex structure of konjac glucomannan in the system,the system showed better properties in the concentration of 0.2%.(2)With the increase of konjac glucomannan mass fraction,the free volume in the system declined.The diffusion coefficient of water molecules and konjac glucomannan chains also decreased.After the system became stable,the interaction between konjac glucomannan and water molecules strengthened,which resulted that the combination rate between konjac glumannan and tyramine decreased.2.The interaction between konjac glucomannan and tyramine in the mesoscopic state level was investigated,the system energy changes,mesoscopic morphology changess,end-to-end distance values,the interface change of stress change and so on were studied..The interactions,viscosity variations and other changes in konjac glucomannan combination system were analyzed.The research showed that:(1)The konjac glucomannan and tyramine conjugates together closely by catalysis of NaBH4,and the aqueous solution existed the hydrogen bonds,Fan Dehua forces ect.,which weakened the coupling tangles in forming a stable system.This study,in a certain extent,could provide some reference value on the mechanism of increasing amino to polysaccharide.(2)By using Dmol3 part,the konjac glucomannan-tyramine-fluorescein isothiocyanate system was optimized.When added the electric field system,b this paper observed the interaction in the system,and the simulation results showed that:the breakdown field strength of konjac glucomannan system was in the vicinity of 179kV/mm;when added fluorescein isothiocyanate to the konjac glucomannan and tyramine combined system,the breakdown field strength were respectively 219kV/mm,220kV/mm,230kV/mm(corresponding to the introduction of fluorescein isothiocyanate sizes were(1×1),(2×2),(3×3)in turn),which was slightly higher than that of konjac glucomannan,and this showed that the mutual effect of konjac glucomannan-tyramine combined system with fluorescein isothiocyanate improved the breakdown properties of konjac glucomannan material.3.By analying the spectral data,it obtained the optimum reaction conditions of preparing konjac glucomannan-tyramine system:(1)the reaction time was 1d,reaction temperature was 30?,reaction pH was 7.5,the amount ratio of tyramine and konjac glucomannan was 1:1.(2)And the substitution degree of fluorescence in konjac glucomannan was 0.71%.4.Through the rheology experiments,it verified the system analysis concluded by molecular simulation.By studying the rheological properties of konjac glucomannan and konjac glucomannan-tyramine system,it showed that(1)konjac glucomannan undergone reductive amination when added tyramine into the system.And with the increase of the shear rate,the coil structure of molecular polymer compound was destroyed,the molecular orientation became stronger,the intermolecular forces reduced,and the viscosity decreased.(2)Under different temperatures,the konjac glucomannan system also showed a pronounced shear thinning phenomenon,namely the characteristics of pseudoplastic fluid.At a low temperature,the motion of konjac glucomannan molecular was low,and the interactions in the system moleculars were strong,which resulted the pseudoplastic characteristics of the solution showed obviously.With the increase of temperature,the Brown motion of the molecules in the solution became intensely,the force between molecules decreased,the dependence of viscosity on shear rate lowered,and the system showed a character of shear thinning and obvious weakening.(3)The dynamic viscoelasticity showed that,in most of the frequency range,the loss modulus G of different konjac glucomannan samples were in a dominantposition.With the reduction of the mass fraction,the storage modulus G' and loss modulus G" were both decreased obviously,which demonstrated that the G' and G" was closely related to mass fraction of the system.And with the reduction of mass fraction of konjac glucomannan system,konjac glucomannan-tyramine system,the amplitude changes of their G'and G"gradually slowed down,which showed that the relationship with frequency of elastic solution became unstuck.