Preparation And Application Of Sensitive Hydrogel Based On Dynamic Boronic Ester Linkages

Hydrogel is a soft polymer material with a three-dimensional network structure formed by a hydrophilic polymer chemically or physically cross-linked in water.However,it is still a great challenge to prepare a gel with excellent capability through simple synthesis steps and low-cost raw materials.In this thesis,based on the dynamic boronic ester linkages,formed by the reaction of boric acid and polyol,two sensitive hydrogels were prepared quickly and easily.The specific research contents are as follows:1.CPBA-PVA hydrogel was prepared using 4-carboxyphenylboronic acid(CPBA)and polyvinyl alcohol(PVA)as raw materials.The tensile strength,sensitivity,identification ability and three-dimensional printability of hydrogels were studied.Conclusions as below:CPBA-PVA hydrogel has pH sensitivity and temperature sensitivity.When the ratio of CPBA to PVA is 3:7,4:7,5:7,the critical transition temperature is 45?,50? and 60?,respectively.CPBA-PVA hydrogel has self-healing properties.The best self-healing performance is CPBA-PVA hydrogel with CPBA and PVA ratio of 4:7.CPBA-PVA hydrogel can specifically recognize copper ions.The CPBA-PVA hydrogel with a ratio of 3:7 of CPBA and PVA and a pH of 7 has a better effect of identifying copper ions.The detection limit of CPBA-PVA hydrogel for identifying copper ions is 0.0003 mol/L,and Single and mixed ions have no effect on the recognition of copper ions.CPBA-PVA hydrogels also have the ability to recognize sugars.Using the temperature to assist the carbohydrate sensitivity of hydrogels,CPBA-PVA hydrogels can recognize mannitol with a concentration higher than 0.3mol/L and fructose with a concentration higher than 0.2mol/L.They have no recognition of glucose,sucrose,D(+)maltose and D(+)galactose.The maximum tensile strength of CPBA-PVA hydrogel is 0.038 Mpa,and the maximum elongation is 12.765 cm.CPBA-PVA gelatin hydrogel has a maximum tensile strength of 0.115 Mpa and a maximum elongation of 4.760 cm.Compared with CPBA-PVA hydrogel,the strength of CPBA-PVA gelatin hydrogel has been improved.CPBA-PVA gelatin hydrogel has 3D printability.When the amount of gelatin added is 3 g and 4 g,CPBA-PVA-gelatin hydrogel has 3D printability;when printing starts,the temperature is 30? and the printing speed is 10%(1 cm/s).2.Using 4-carboxybenzeneboronic acid(CPBA),polyvinyl alcohol(PVA)and 1,4-benzenediboronic acid(DPBA)as raw materials,CPBA-PVA-DPBA hydrogel was prepared.Relationship between DPBA content and CPBA-PVA-DPBA hydrogel formation and the self-healing and sensitivity of CPBA-PVA-DPBA hydrogel were studied.conclusion as below:CPBA-PVA-DPBA hydrogel is not sensitive to temperature and pH,stable below 70?,and deteriorated above 70?.CPBA-PVA-DPBA hydrogel is self-healing and can heal itself quickly.CPBA-PVA-DPBA hydrogel has carbohydrate sensitivity.As the concentration of glucose solution,fructose solution,D(+)maltose solution and D(+)galactose solution increases,CPBA-PVA-DPBA hydrogel have more parts dissolvesd.CPBA-PVA hydrogel has different properties from CPBA-PVA-DPBA hydrogel.CPBA-PVA hydrogel has temperature and pH sensitivity.The CPBA-PVA-DPBA hydrogel is stable to temperature and pH.But CPBA-PVA hydrogels have no carbohydrate sensitivity,CPBA-PVA-DPBA hydrogels have carbohydrate sensitivity.