Construction Of Cellulose-based Hydrogels And Its Properties

As a natural polymer material with huge reserves and wide distribution,cellulose has the advantage of good biocompatibility,regeneration and biodegradation.However,high hydroxyl ratio in molecular chains is easy to form hydrogen bonds,which brings challenges to its processing and application and limits its application field expansion.Especially in the field of biological materials and medical applications,cellulose-based hydrogels also have the characteristics of poor mechanical properties and low biocompatibility.In this paper,mineralized hydrogels,green hydrogels and super strong and tough hydrogels were prepared by chemical and physical crosslinking of cellulose based materials.The specific work is mainly divided into the following three parts:Part I:the chemical cross-linking between cellulose dissolved in low temperature lye and epichlorohydrin is used as the framework to further build hydrogen bond association network under the action of acid.In addition,the preparation conditions of the hybrid gel were optimized,and hydroxyapatite(HAp)was loaded on the surface of the hybrid gel to obtain excellent performance of the mineralized hybrid crosslinked cellulose hydrogel,whose tensile strength is 490 k Pa,elongation is 93%,and deformation rate is about 5%in phosphate buffer(p H=7.4).The introduction of bioactive HAp makes the hybrid hydrogel material beneficial for inducing the differentiation of bone marrow mesenchymal stem cells(BMSCs),which has potential application value in tissue engineering.Part II:the cellulose dissolved in low temperature alkaline solution reacted with disodium ethylenediaminetetraacetic acid.On this basis,the hydrogen bond association network was constructed by further acidic stimulation.By optimizing the preparation parameters of the gel,excellent and safe high-strength swelling resistant cellulose hydrogel was obtained,with tensile strength of 643 k Pa and elongation of 94%.The deformation rate in 37°C phosphate buffer(p H=7.4)is about 1%.Through the simple preparation strategy of‘‘gel frame+acid stimulation’’,the hydrogel obtained is green and safe,so it has great potential application value in biological tissues.PartШ:a new way to prepare hydrogels with excellent mechanical properties was studied by introducing shear modified carboxymethyl cellulose(TMCMC)into hydrophobic association.The reaction of TMCMC with acrylamide(AM)was confirmed by ~1H-NMR and FTIR analysis,and the hydrophobic association hydrogel(TMCMC/HPA)with shear modified carboxymethyl cellulose had a dense and uniform network structure.The fracture stress,elongation and tensile toughness of TMCMC/HPA are 1.17 MPa,3717.05%and15.68 MJ/m~3,respectively.The toughening mechanism and strain response of the system were investigated,which greatly broadened the application prospect of hydrophobic associating hydrogels.