Synthesis And Adhesion Properties Of Polymers Grafted With Catechol Groups

Adhesives with fascinating wet adhesion ability have received increasing attention in biomedical field,especially for tissue adhesion and medical dressings.Inspired by mussels,catechol chemistry provides the feasibility of the preparation of underwater adhesives.The side chain of catechol groups can form the interaction of chemical coordination and reaction crosslinking,providing stable underwater adhesion on the surface of substrate.Layer-by-layer assembly(LbL)has become one of the classical methods for the preparation of polymer films due to its simple preparation process,controlled structure and composition,and easy functional integration.The LbL can be used to prepare polymer films in aqueous solution,which will be significant to introduce the water-resistant group of catechols into the polymer and prepare water-resistant adhesive films assembled by LbL.In this dissertation,water-resistant adhesive films were prepared by LbL the building blocks grafted covalently with catechol groups.Based on carbodiimide coupling reaction of N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride(EDC),the 3-(3,4-dihydroxyphenyl)propionic acid and dopamine hydrochloride(DA)were covalently grafted on bio-compatible chitosan hydrochloride(CHI)and hyaluronic acid sodium(HA).The(CHI-C/HA-D)*n(n presents the deposition cycles)adhesive films were prepared by dipping LbL assembled method.The water-resistant adhesive films show an excellent underwater mechanical connection(0.82 ± 0.19 MPa)and a high transmittance(more than 83%)in the visible region.Furthermore,the free-standing adhesive films were prepared by mechanical exfoliation in the water.The water-resistant free-standing adhesive films demonstrated an excellent underwater mechanical connection(0.40 ± 0.22 MPa)and a high transmittance(more than 83%)in the visible region,and showed outstanding adhesion with fresh porcine heart,providing the potential application in biomedical field.Similarly,the(EPL-C/HA-D)*n adhesive films were prepared by dipping LbL antibacterial ε-poly(?-lysine)(EPL)grafted with 3-(3,4-dihydroxyphenyl)propionic acid and bio-compatible HA-D.Furthermore,the free-standing adhesive films were prepared by mechanical exfoliation in air.The free-standing adhesive films with excellent underwater adhesive ability(0.05 ± 0.04 MPa)and high optical transmittance(more than 55%)was demonstrated.It should be noticed that the underwater mechanical stability of free-standing adhesive films was improved by the crosslinking using EDC.The adhesive films were prepared by LbL assembly branched poly(ethylenimine)(bPEI)and HA-D by spraying method.Lap shear testing demonstrated the excellent freeze-resistant,water-resistant,and room temperature adhesive abilities.Optical analysis showed the excellent optical transmittance(more than 59%).It should be noticed that the adhesive films were prepared by fast spraying LbL assembly,and they show excellent freeze-resistant,water-resistant,and room temperature adhesive abilities.