Study On Preparation And Properties Of High Strength And Multifunctional Hydrogels

Hydrogels,which were soft materials that consist of a large amount of water and a three-dimensional cross-linked hydrophilic polymer network.Due to perfect biocompatibility,larger network aperture and similar microenvironment compare with extracellular matrix,hydrogels have been widely used in biomedical field,such as wound dressings,drug release,soft tissue replacement and repair,tissue engineering and biosensors et al.However,poor mechanical properties of traditional hydrogels limited practical applications of biomedical field.At present,significant effort was directed toward the improvement of the mechanical properties of hydrogels.After satisfying the mechanical properties,more and more attention has been paid to the study of the multi-functions of hydrogels.In our research,based on ionic crosslinking,nanofiber enhanced and mussel adhesion mechanism,we manufactured a kind of dual ionically cross-linked hydrogel with ultra-tough,self-healing and physiological environment stable and a kind of super-tough hydrogels with self-adhesive and biocompatibility.The specific content as follows:1.Dual ionically cross-linked hydrogels with ultra-tough,stable,and self-healing propertiesUltra-tough,stable and self-healing hydrogels dual ionically cross-linked were prepared by one-pot method,that was 2-hydroxypropyltrimethyl ammonium chloride chitosan?HACC?/poly?acrylic acid??PAAc?-Fe³⁺hydrogels were synthesized by the in-situ polymerization of acrylic acid in a mixed solution of 2-hydroxypropyltrimethyl ammonium chloride chitosan?HACC?and ferri ion(Fe³⁺).In hydrogel networks,positively charged macromolecule HACC and metal ion Fe³⁺acted as macromolecular cross-linking agent and small molecular cross-linking agent,respectively,to form ionic bonds with carboxyl groups in PAAc polymer chains.The two dynamic ionic bonds endued the hydrogels with ultra-high mechanical strengths?tensile strength of 9.86 MPa and compressive stresses greater than 96 MPa at 99%strain?,outstanding self-healing properties?almost completely toughness recovery within 5 h without any external stimuli?and excellent self-recoverability?74%self-healing efficiency?.The swelling tests showed that the hydrogels possessed good anti-swelling and physiological environment stability,and the cytotoxicity test in vitro showed that the hydrogel had good cell compatibility.The ultra-tough,stable,self-healing and cell compatibility hydrogels prepared in this study have great potential for cartilage repair and replacement.2.Bacterial cellulose nanofiber reinforced mussel-inspired self-adhesion and super toughened hydrogelBacterial cellulose nanofiber?BC?used as nano-reinforcement material,and pre-polymerization of dopamine?DA?monomer in alkaline oxygen-containing BC dispersion solution to form BC-PDA complexes.And then the hydrogels were fabricated by the in-situ polymerization of acrylamide?AM?in BC-PDA complexes dispersion solution.Gel formation prevented the excessive oxidation of polydopamine,and enough free catechol groups were retained in the hydrogel network giving the hydrogel good adhesion with repeatability and long-term preservation.In addition,BC,as a nano-reinforcing material,endow hydrogels with super tensile properties and high mechanical strength.The hydrogels also showed good self-recovery performance,and the self-recovery could be achieved after stretching or compression without external stimulation.In vitro cell experiments indicated that the hydrogels were nontoxicity.The above results revealed that hydrogels with the ultra-tough,self-adhesive and cytocompatibility have great potential as wound dressing materials.