Preparation And Properties Of Non-covalent Bonded Polyacrylic Conductive Hydrogel

As a water-containing soft material,hydrogel can be endowed with good flexibility,stretchability,biocompatibility and conductivity through structural design.It shows great potential in manufacturing flexible sensors and can be applied.In wearable devices,electronic skins for robots,and human health monitoring.As a flexible sensor,in addition to having good mechanical strength and toughness,hydrogels also need to have some functionalities,such as conductivity,self-healing,and adhesive.So far,some hydrogels have been successfully prepared as sensors that can respond to external stimuli.However,hydrogels with good mechanical properties and multiple functions are not common,which greatly limits the application of hydrogels in the field of flexible sensors.The conventional hydrogel crosslinked with covalent bonds is easily broken after being stressed,and it is difficult to have good mechanical properties,and it cannot be used as a flexible sensing material.The introduction of non-covalent bond physical effects in the hydrogel network is an effective way to improve the mechanical properties of hydrogels.Common non-covalent bonds include hydrogen bonding,hydrophobic association,and ionic crosslinking.And the introduction of these non-covalent bonds can also give the hydrogel good self-healing properties.Therefore,in this thesis,based on non-covalent bonding,an ionic conductive hydrogel with polyacrylic acid as the main body was constructed,and various properties of the hydrogel were studied.The research mainly includes two parts.In the first part,a polyacrylic acid/modified polyethylene glycol conductive hydrogel was prepared.Firstly,maleic anhydride?MAh?was used to modify polyethylene glycol?PEG?,and carboxyl groups?-COOH?were connected to both ends of the molecular chain of PEG.Sexual success,PEGDMA is generated.A polyacrylic acid/modified polyethylene glycol conductive hydrogel was then prepared.The effects of PEGDMA/AA,the molecular weight of PEG and the concentration of FeCl₃ on the properties of hydrogels were investigated.The maximum breaking strength and toughness of the hydrogel reach 658KPa and 3.38MJ/m³.At the same time,polyacrylic acid/modified polyethylene glycol conductive hydrogels also showed excellent self-healing properties.In addition,the conductive sensing test shows that the hydrogel has good conductivity and very high sensitivity.In the second part,a polyacrylic acid/chitosan quaternary ammonium salt viscous conductive hydrogel was prepared.The modified polyethylene glycol in the first part of the hydrogel was replaced with a chitosan quaternary ammonium salt?CAS?to prepare the hydrogel.Through the rheological performance test and ultraviolet test,it is proved that there are many covalent bond bonds in this system.The experiment also explored the effect of CAS content and FeCl₃ content on the hydrogel performance.The hydrogel has good mechanical properties.The maximum breaking strength and toughness reached 827Kpa and the 5.1MJ/m³ peeling force test showed that the hydrogel has a certain adhesive.Its maximum adhesive strength is 110N/m.The hydrogel also has good electrical conductivity,with a maximum conductivity of 12.2ms/cm.According to the conductive sensing test,it can be seen that the hydrogel exhibits great strain sensitivity.In addition,the hydrogel has obvious anti-swelling properties and excellent self-healing properties.This kind of hydrogel with good mechanical properties and multiple functions is expected to be used as a flexible sensing material with excellent performance in more fields.