Study On Preparation And Properties Of Thermosensitive And PH Sensitive Guar Gum

Guar gum,as the natural polymer polysaccharide with the largest viscosity in nature,has a wide application value.However,guar gum is usually modified to enlarge its application area due to its physical and chemical properties.In this paper,we studied the temperature sensitive modification and PH sensitive modification of guar gum.In this paper,the thermosensitive modification of guar gum was firstly studied.With guar gum as raw material and isopropyl glycidyl ether as etherification agent,Using the combination of orthogonal experiment and single factor experiment discussing the optimum preparation conditions for preparing 2-hydroxy-3-isopromethoxy propyl guar ether?HIPGG?in detail.And on this condition,the different degree of substitution of HIPGG was prepared.The effect of different degree of substitution,HIPGG concentration and NaCl content on the LCST behavior of HIPGG solution was studied,which found that when the degree of substitution increased from 0.83 to 2.78,the LCST value decreased from 54.9?to 36.1?;When the concentration of HIPGG solution increased from 0.5 g/L to 10 g/L,the LCST value of HIPGG decreased from 56.1?to 48?;When the NaCl content was increased from 0 to25 g/L,the LCST value of the solution decreased from 51?to 39.1?.Therefore,the LCST of HIPGG solution can be adjusted by the degree of substitution,concentration and inorganic salts.The solubilization behavior of Nile red with different degrees of substitution was studied.With the increase of the degree of substitution of HIPGG,the maximum solubilization of Nile red gradually increased.The temperature control release behavior of the HIPGG solution that solubilized Neal red was studied,which found that when the temperature is lower than the LCST value,the release of HIPGG is especially slow.When the temperature is higher than the LCST value,the UV absorption peak intensity of HIPGG solution rapidly decreased,and the higher the temperature,the faster the decrease.In this paper,the PH sensitive modification of guar gum was secondly studied.Carboxymethyl guar gum with different degrees of substitution was prepared with Carboxymethyl method by adjusting the amount of chloroacetic acid.Taking carboxymethyl guar gum with 0.77 degree of substitution as raw material to discuss the optimum conditions for preparing carboxymethyl guar gum through single factor experiment.The particle size of 240 nm polystyrene photonic crystal was successfully prepared by non emulsion aggregation method,and it was combined with carboxymethyl guar gum to prepare pH sensitive carboxymethyl guar gel photonic crystal membrane by single factor experiment,and The results founded that carboxymethyl guar gum concentration was 5%,Dosage of 25%NaOH was 10?L,Dosage of vinyl sulfone crosslinking agent was15?L.The microcosmic filling situation of carboxymethyl guar gum gel photonic crystal membrane was detected by electron scanning electron microscope,and the filling effect was good.The response detection of carboxymethyl guar gum gel photonic crystal membrane to alcohol concentration,pH and heavy metal ions such as Pb²⁺,Cd²⁺,Hg²⁺were investigated.The results showed that with the increase of PH from 1 to 13,the reflection wavelength of the carboxymethyl guar gel film was gradually redmoved from 558 nm to 686 nm,and the color from green gradually deepened to deep red,and as the concentration of ethanol gradually increased,the reflection wavelength was gradually blue shift and the optimum concentration of ethanol response was 60%.The best response concentrations of gel films in Cd²⁺,Pd²⁺and Hg²⁺solutions were 0.05 mol/L,0.01 mol/L and 0.005 mol/L,and comparing Pd²⁺and Cd²⁺,Hg²⁺has better responsiveness to carboxymethyl guar gel photonic crystal film.