Preparation And Study Of High Performance Hydrogels Based On Protein-based Adhesives Of Marine Organisms

Many marine organisms are able to bond various substrates underwater using protein-based adhesives,which has attracted wide attention.Recent years,various biometic methods about catechol chemistry have been developed to fabricate hydrogels.Bioinspired adhesive hydrogels have aroused increasing attentions.However,it is still a challenging to design and prepare a bioinspired hydrogel with excellent mechanical property,extremely strong adhesion and other high performances through a simple method.In this paper,based on the composition and adhesion mechanism of adhesion proteins,we designed and prepared four different kinds of bioinspired adhesive hydrogels:PAA/PMD,PAA/PAD,PAAD/PM and PAAD/PA hydrogel,systematically studied the properties of these hydrogels and analyzed the internal mechanism by transverse comparison.The main works and results are summarized as follows:1.Based on the composition of adhesion proteins:DOPA,anionic proteins and cationic proteins,we designed and prepared PAA/PMD hydrogel,which involved a large number of reversible sacrificial interactions,such as electrostatic interactions and hydrogen bonds.Those interactions made a great contribution to the ultrastretchability and the self-healing ability.The fracture elongation is up to 1.391× 104%.Moreover,after soaking in water,the hydrogel showed negative-swelling behavior and enhancement of mechanical strength,owing to the formation of strong electrostatic attraction and supramolecular structure.Therefore,the lap shear adhesion strengths of the hydrogel also demonstrated significant increase from 177 KPa to 1.37 MPa.In view of the above-mentioned remarkable properties,we believe that this work not only opens a new window to the design of novel underwater adhesive and tissue sealant,but also provides a reference value for further revealing the mechanism of underwater adhesion of marine organisms.2.In order to further study the role of the hydrophobicity of the acyl oxygen structure in the gel system,and to further enhance the internal dynamic interaction content to enhance its self-healing properties,we prepared PAA/PAD hydrogel containing amide structure cations.The hydrogel demonstrated excellent stretchability and adhesion.Moreover,the hydrogel also exhibits excellent self-repairing,remolding and electrical conductivity.In view of the above-mentioned remarkable properties,we believe that this hydrogel can be applied in the field of flexible electronic skin.3.In order to better study the internal mechanism of hydrogel,we transferred the DMA molecule from the polycation chain to the polyanion chain,namely PAA chain,and prepared PAAD/PM and PAAD/PA hydrogels.By comparing the properties of the four hydrogels,we can find that the mechanical properties of the hydrogels change abruptly after changing the location of DMA,but the swelling properties do not change much.Therefore,it is reasonable to think that the crosslinking of hydrogel is dominated by electrostatic interaction before immersion and by hydrogen bonding after immersion.