Preparation And Properties Investigation Of PAM-Based Hydrogel Enchanced By Branched Polymer

Due to the single performance and poor mechanical performance of traditional hydrogels,the application in real life is restricted to a great extent.In order to meet the needs of practical life,researchers have done a lot of research in recent years and prepared many hydrogels with excellent properites,which greatly enriched the types of hydrogels.From the perspective of improving the performance of PAM hydrogels,branched polyethylenimine(PEI)with a large number of-NH2 and-NH-groups was introduced into PAM hydrogels network to prepare PEI/PAM chemical hydrogels with an enhanced toughness and PEI/PAM physical hydrogels with exellent fluidity,respectively.In addition,The injectability of PEI/PAM/SiO2 ternary physical hydrogel was studied by introducing SiO2 nanoparticles into PEI/PAM physical hydrogel network.The main content of this work is as follows:(1)A series of PEI/PAM chemical hydrogels,which introduced PEI into chemically crosslinked polyacrylamide(PAM)hydrogels matrix,were prepared by in situ radical polymerization and their performance were tested.During the frequency sweep,all hydrogels showed G’>G",indicating the solid-like behavior and elastic nature.With the increase of Bis component content,the crosslinking degree of the network increased,so the G’ value increased with the increase of Bis.As the content of PEI component content increased,the G’ value decreased.This is because that PEI affects the intramolecular hydrogen bonding between PAM chains,thus affecting the effective cross-linking degree of the system.Shown as strain sweep,PEI/PAM hydrogels broke at larger γc than the pure PAM chemical hydrogels,indicating that the toughness of PEI/PAM chemical hydrogels has been improved by introducing PEI(2)A series of PEI/PAM physical hydrogels were prepared by in situ radical polymerization in the absence of chemical crosslinking agents,and rheological tests were carried out.The results of the steady shear rheological measurements showed that the viscosity of PEI/PAM physical hydrogel decreased and the fluidity became better with the increase of PEI concentration.Shear thickening occured when PEI with high molecular weight was added to PAM physical hydrogel.It is due to the formation of local network structure or network structure throughout the whole solution system during the shear process,resulting in a rapid rise in viscosity.The phenomenon of shear thickening was dependent on the monomer AM concentration,PEI concentration and PEI molecular weight.From the analysis of relevant parameters of shear thickening properties,it can be seen that the effect of shear thickening of AM4-PEI0.12-70000 hydrogel was obvious(3)In order to achieve the injectability of PAM physical hydrogels,a series of PEI/PAM/SiO2 ternary physical hydrogels were prepared.PEI was introduced into the PAM network to improve the fluidity of PAM physical hydrogels.SiO2 nanoparticles were added to improve the strength and network stability of PEI/PAM physical hydrogels.The results of the stable cycle performance test showed that the G’ of AM5-PEI0.02-TM500.08 and AM5-PEI0.02-SM0.08 hydrogels can recover 81.2%and 85.3%respectively after three strain-time sweep cycle tests,showing good cycle stability and self-recovery performance.