| The human body owns complex environments with acid and alkali changes,no light inside,and light on the surface of the body,so we produce the self-healing hydrogels which are suitable for the complex environments of human body.And the hydrogel can achieve self-healing under acid,alkaline,neutral or light environment,with potential applications in the fields of biological materials.Also,the interpenetrating polymer network(IPN)hydrogels are produced by waterborne polyurethane(SH-WPU)and cross-linked polyamide amine(PAMAM),where SH-WPU is as the first networking and contains reversible covalent bonds,and PAMAM is as the second networking and contains reversible non-covalent bonds.Firstly,we synthesize the crosslinking polyamide amine which is suitable for the second network of IPN hydrogels.The formation of polymer gels are judged by inverted test tube method and rheological test.The results show that these methods are effective during determining its formation.And according to the analysis of various factors affected its formation,it shows that the gels can be prepared when they are in the methanol solvent,R = 1.25,50 ? and the monomer concentration(mass fraction)over 22%.Through the infrared analysis of polyamide amine(PAMAM),N,N-methylenebisacrylamide(MBA)and N-aminoethylpiperazine(AEPZ),it shows that the chemical crosslinking reaction between MBA and AEPZ can be happened and PAMAM is then generated.And infrared analysis of PAMAM with LiBr and PAMAM with no LiBr shows that the cross-linked polyamide amine containes abundant hydrogen bonds.The equilibrium swelling ratio tests of PAMAM-1(monomer concentration 22%),PAMAM-2(monomer concentration 27%)and PAMAM-3(monomer concentration 32%)show that PAMAM-1 has the highest swelling ratio.Through the dynamic modulus tests,we know that the G 'of PAMAM-1,PAMAM-2 and PAMAM-3 are 5000 Pa,15000Pa and 24000 Pa respectively,indicating that the gels have good elasticity and belong to chemical crosslinking.Taking PAMAM-2 as an example,it shows that the cross-linked polyamide amine can be repaired by hydrogen bonds.Then,we synthesize polyurethanes which are as the first network with reversible covalent bonds(disulfide bonds and acylhydrazone bonds).After that,the polyurethanes(SH-WPU)are swollen in the different mass concentrations of polyamide amine(PAMAM)monomers solution(the mass fraction is 22%,27% and 32% respectively).Finally,IPN-1,IPN-2 and IPN-3 self-healing gels can be prepared successfully.And the mass ratio of SH-WPU to PAMAM is 100: 36,100: 60 and 100: 76 respectively.It can be determined that disulfide bonds and acylhydrazone bonds are combined in the SH-WPU and hydrogen bonds exist in the PAMAM by FTIR.Also,FTIR and DSC tests show that IPN structure is produced by SH-WPU and PAMAM.DSC and SEM test results illustrate that the compatible of SH-WPU and PAMAM is good,and at room temperature,the materials are in high-elastic state,and the chains can move,which provide the possible for self-healing.The results of tensile test show that the self-healing time for 1 h and 24 h,IPN-3 owns the highest self-healing efficiency,35% and 57% respectively.Self-healing for 48 h,IPN-2 owns the highest self-healing efficiency,at 93%.Finally,we synthesize the IPN self-healing hydrogels which can be applied to the human bodies.The IPN self-healing hydrogels named IPN-W1,IPN-W2 and IPN-W3 respactively can be prepared by replacing the IPN-1,IPN-2 and IPN-3 methanol gels with deionized water.The equilibrium swelling ratio shows that the IPN-W2 has the highest equilibrium swelling ratio,at 354%.The swelling kinetics shows that the swelling rate rises first and then decreases.Also,the tensile test results of different self-healing time show that the self-healing for 1 h and 24 h,IPN-W3 owns the highest self-healing efficiency,up to 32% and 56% respectively.And self-healing for 48 h,IPN-W2 has the highest self-healing efficiency,at 87%.In conclusion,IPN-W2 is the best self-healing hydeogel. |
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