| Hydrogels with good biocompatibility and stimulus responsiveness have potential applications in tissue engineering,artificial intelligence and soft robotics.However traditional hydrogels have some disadvantags such as instability,poor mechanical strength and short service life.It is imperative to prepare new hydrogels with high mechanical properties and good self-healing properties.The key to achieve high strength and good healing properties is to design reasonable gel network structure and cross-linking method.The dual-physical cross-linking network structure combines excellent mechanical property and dynamic reversibility.Therefore this network structure is valuable to fabricate hydrogels with better self-healing performance and high-strength.In this study,acrylic acid,acrylamide and gelatin are used to prepare three different dual-physical network hydrogels with high mechanical properties and self-healing properties.The main research contents are as follows:(1)Poly(acrylamide-co-acrylic acid)/Gelatin physical cross-linking double network hydrogel(PAA-co-PAM/Gelatin hydrogel)is prepared with acrylic acid,acrylamide and gelatin as monomers by "one-pot method".The effects of the concentration of poly(acrylamide-co-acrylic acid)copolymer and the mass fraction of gelatin on the mechanical and self-healing properties of hydrogel are explored to obtain the optimum preparation process of the gel.Results show that when the polymer monomer concentration is 5mol·L-1,the gelatin weight content is 30%,the gel could get the best mechanical properties.The elastic modulus,breaking strength,breaking elongation,dissipated energy and the strain of the gel are 361.8kPa,605.3kPa,835%,806.5kJ·m-3 and 300%respectively.PAA-co-PAM/Gelatin can be quickly repaired within 4 hours at room temperature,and the repair efficiency is greater than 80%.(2)In order to improve the crosslinking strength of hydrogen bonds in the poly(acrylamide-co-acrylic acid)network of the gel,the monomer with quadruple hydrogen-bond(UPy)is synthesized to get P(AA-co-AM-co-UPy)/Gelatin hydrogel.The effects of UPy content on the mechanical,swelling and self-repairing properties of the gel are explored to get the optimum preparation process.The relationship of the temperature and the swelling volume of the gel are studied.The experimental results show that the best mechanical properties of the gel can be obtained when the UPy monomer weight content is 5%.The breaking strength,elastic modulus,compressive strength and compressive modulus are 1050kPa and 726kPa,11.7kPa and 802.5kPa,respectively.The hydrogel has temperature responsiveness and swelling resistance(swelling ratio of 2.6).At the same time,the gel has a certain self-repair performance at room temperature,and the self-repair efficiency is greater than 60%.(3)In order to improve the self-repair efficiency of the gel,the gelatin network in the gels are modified.P(AA-co-AM)-GelMA-TA hydrogel are prepared by one-step radical polymerization with formamidated gelatin(GelMA),acrylic acid,and acrylamide as raw materials in tannic acid(TA)solution.The influence of GelMA and polypropionic acid-acrylamide mass fraction,the soaking time in TA solution on the mechanical,swelling and self-repairing properties of the gel are studied to get the relationship between monomer concentration and gel structure.The experimental results show that when the GelMA content in the hydrogel is 10%and the soaking time is 24h,the tensile strength,breaking strain,elastic modulus,compression modulus of CPx-GelMA-TA hydrogel are 1863kPa,331.2%,1125kPa and 1678kPa.CPx-GelMA10-TA hydrogel has swelling resistance and the minimum swelling ratio is 1.3.The gel has excellent self-healing,self-healing properties and can be self-healed at room temperature without external stimulation with the repair efficiency higher than 75%.By modifying the poly(acrylamide-co-acrylic acid)network and the gelatin network,the prepared three kinds of hydrogels have good self-healing properties and mechanical properties.The mechanical strength of the gel can be controlled with different variables.This kind of hydrogel with high strength,self-healing and low swelling properties is expected to become a substitute for biological soft tissue scaffolds. |
