Study On Preparation And Performance Of Temperature Sensitive Guar Hydrogel

In order to increase the added value of natural polysaccharide guar gum and broaden its application range,a series of guar gum-poly(N-isopropylacrylamide)(GG-PNIPAM)composite hydrogels were prepared in this study;Infrared spectrometer(FTIR),scanning electron microscope(SEM),differential scanning calorimetry(DSC),ultraviolet-visible spectrophotometer(UV-Vis),thermal weightlessness analysis(TGA),texture analyzer,universal testing machine,etc.The structure and performance are characterized.Exploring and analyzing the swelling ability of a series of samples through swelling degree experiments and mathematical models;exploring its application by studying the temperature response deformation,plasticity and drug controlled release ability of guar gum.The research results include the following aspects:(1)N-isopropylacrylamide(NIPAM)and N-(3-dimethylaminopropyl)methacrylamide(DMAPMA)were successfully grafted onto guar gum,and GG-PNIPAM composite in 65℃ water The appearance of the hydrogel changed from transparent to white and opaque.As the percentage of the NIPAM substance increases,the difference between the equilibrium swelling rate of the GG-PNIPAM hydrogel at 20°C and the equilibrium swelling rate at 60°C increases from 284% to 3977% and the absorbance at 60°C increases.The minimum eutectic temperature(LCST)of hydrogel samples G0.5M2N70,G0.5M2N75,G0.5M2N80,G0.5M2N85,G0.5M2N90,G0.5M2N95 are 36.5℃,40.2℃,45.8℃,42.4℃,41.5℃ And 42.7°C.(2)The addition of guar gum can increase the gel strength of GG-PNIPAM composite hydrogel.The gel strength of the sample with guar gum content of 1.5% after immersion in sodium tetraborate reaches 1400.97 g,which is 4.4 times that of the blank sample..When the content of the cross-linking agent is 1.5%,the gel strength reaches the maximum value of 1153.29 g in the same group;the strength of the sample with the initiator content of 2% reaches the peak value of 938.13 g in the same group;when the monomer content is 12%,the gel strength of the sample Reached the peak of 938.13 g in the same group.Immersion in a moderate sodium chloride solution can greatly improve the mechanical properties of the sample hydrogel.Samples immersed in sodium chloride solutions with concentrations of 1mol/L,2mol/L,3mol/L,4mol/L,and 5mol/L The elastic modulus of hydrogel is 0.02 MPa,27.85 MPa,18.62 MPa,34.82 MPa,35.75 MPa.The modulus of elasticity of the sample soaked in 5mol/L Na Cl is 1787.5 times that of the sample soaked in 1mol/L Na Cl.(3)The equilibrium swelling rate of the crosslinking agent content of 2% is the maximum value of the same group—1795.3%;the equilibrium swelling rate of the initiator content of 5% is the maximum value of the same group—1829.2%;the equilibrium of the monomer content is 10% The swelling rate is the largest value in the same group—1752.3%.The swelling model and mechanism analysis results show that the first-order kinetic swelling model has a sample water with a cross-linking agent(MBA)content of 2.5%,an initiator(APS)content of 1%,and a monomer content of 10% and 14%.For the gel,the remaining sample hydrogels follow the second-order kinetic swelling model;the 0.5% crosslinker content belongs to Fickian swelling.Crosslinker content of 1%,initiator content of 1% and 3%,monomer content of 8% and 12%,and 14% belong to the first-order diffusion in the Fickian swelling process.(4)The GG-PNIPAM hydrogel sample has shape memory function under high temperature-low temperature-high temperature thermal cycling conditions,and its temperature-sensitive deformation behavior is affected by the gel volume and water temperature;the gel has a significant temperature when used as a drug carrier Responsiveness: Compared with 25℃,the loading rate of BSA samples was faster and the cumulative release rate was higher at 37℃.With the increase of the NIPAM monomer ratio,the release rate of the drug in the early stage was faster and the cumulative release rate was higher.Close to 100%.GG-PNIPAM composite hydrogel has potential application prospects in the fields of smart materials and controlled drug release.