Investigation On The Preparation And Performance Of High Strength Macroporous Hydrogel

This thesis firstly reviewed the types of high-strength hydrogels,the preparation of macroporous hydrogels,and the research progress in the fields of solar vapor evaporation,and then discussed in depth the application of high-strength hydrogels and hydrogels based interfacial solar vapor evaporation.Due to the limitations of poor mechanical strength of porous hydrogels,this thesis proposed a method for preparing high-strength porous hydrogels based on sodium chloride as the porogen and double-crosslinked hydrogels as the skeleton to solve this problem.The thesis investigated the mechanical performance of porous hydrogel and the application in interfacial solar steam generation.The main research content and conclusions of this thesis are as follows:(1)The pre-polymerization solution is composed of porogen sodium chloride particles,polymerized monomer N-isopropylacrylamide and acrylic acid,and chemical crosslinking agent methylene bis-acrylamide.After the pre-polymerization solution was configured,the sodium chloride particles were filled into the pre-polymerization solution.The hydrogel were prepared by in situ radical polymerization.After that,the hydrogel was immersed in the iron ion solution and deionized water to obtain the porous hydrogel samples.Through the characterization of SEM,the macroporous structure of the material was clarified,and its size ranged from tens to hundreds of microns;through the system characterization of the electronic universal material testing machine,we found that the mechanical strength of the prepared sample was highly correlated with acrylic acid content.When the acrylic acid content increased from 25%to 32.5%,the compressive strength increased continuously.Under the condition of a fixed strain of 80%,the compressive strength increased from 2.65 MPa to 5.77 MPa.The elastic modulus increased from 0.19 MPa to 3.15 MPa;due to the temperature sensitivity of N-isopropylacrylamide,when the test environment is kept at 50°C,the mechanical strength was further improved,showing temperature responsiveness.In addition,the prepared sample had excellent elasticity and self-recovery properties.The material still maintained a certain hysteresis loop area after 20 cycles.After 30 minutes of recovery time,the mechanical strength,hysteresis loop area and residual strain had been recovered.In addition,due to the structure of the large holes,the responsiveness of the material was fast.In hot water at 50°C,it can roll 360°in 15s,and it could be recovered to its original state in cold water at 10°C in 30s.(2)The pre-polymerization solution is composed of porogen sodium chloride particles,polymerized monomer acrylamide and acrylic acid,and chemical crosslinking agent methylene bis-acrylamide.The pre-polymerization solution was in-situ polymerized after filling the porogen and then soaking it in iron ion solution and deionized water to form macroporous hydrogel materials.The light-to-heat conversion material,polypyrrole,was in-situ polymerized to introduce into the hydrogel network.The interfacial solar steam generation performance of the prepared materials was systematically characterized in this paper.The research shown that the material under the 1 sun irradiation,the rate of solar vapor generation reached 1.92Kg/m~2·h.The rate reached 5.26 Kg/m~2·h under 3 sun irradiation which indicated the macroporous structure could quickly replenish the lost water,reflecting the advantages of the macroporous hydrogel.In the characterization of practical applications,this paper selected the organic dyes and simulated seawater were used as the treatment objects,and the collected water was evaluated.The study shown that the removal ratio of organic dyes in the treated water is 99%,and the salt content in the treated seawater was much lower than that of WHO and China standard for drinking water.