Preparation Of Urushiol-based Graphene And Its Application In Epoxy Resin Coatings

In this paper,the properties,preparation and modification methods of graphene and its application in anticorrosive coatings were reviewed.Based on the molecular design,the urushiol derivatives with epoxy functional groups were synthesized and used as reducing agent and modifier of graphene oxide to prepare modified graphene with good solubility with epoxy resin.Then,the modified graphene was used as the filler to prepare graphene/epoxy resin composite coating with excellent anticorrosive properties.The research content is as follows:(1)Based on the unique chemical structure of urushiol,two different structures of urushiol glycidyl ether were synthesized by using the reactivity of hydroxyl group and C=C on the long side chain of urushiol,respectively.One product is urushiol glycidyl ether with two phenolic hydroxyl groups,named EU,obtained by the epoxidation of C=C on the long side chain of urushiol through the Prilezhaev reaction.The other is urushuiol based epoxy resin,called UE44,which is synthesized via the epoxy ring-opening reaction of epoxy resin with urushiol hydroxyl group.Then,the two urushiol derivatives with epoxy functional groups were used as the reducing agent and modifier of graphene oxide to obtain two kinds of functional graphene with long carbon chain and epoxy group on the surface and good dispersion in organic solvent,named EU-GO and UE44-GO.(2)The above two kinds of epoxidated urushiol modified graphene were used as fillers to compound with epoxy resin to prepare the anticorrosive coating of graphene/epoxy resin.The effects of epoxidated urushiol modified graphene on the curing kinetics,thermal stability,corrosion resistance,wettability,adhesion and hardness of composite coatings were investigated.The results showed that the graphene modified with epoxy groups and long alkyl chains was dispersed well in the epoxy resin matrix and interfacial with the epoxy resin matrix,which was conducive to heat transfer and promoted the curing reaction of the epoxy resin.And due to the good dispersion of the modified graphene in epoxy resin matrix,doping a small amount of modified graphene can effectively improve the hardness and thermal stability of the coating,as well as the barrier effect of graphene sheets,effectively reduce the water absorption of the coating and improve the corrosion resistance.(3)A new graphene/zinc composite paint was prepared by using urushiol epoxy resin modified graphene(UE44-GO)as replacement of zinc powder partially in epoxy zinc rich primer.The effect of modified graphene on the properties of epoxy zinc-rich coatings was studied.It was found that the properties of hardness,water absorption resistance and corrosion resistance of the epoxy primer coating with 20% zinc content were significantly improved after the addition of 0.075 wt.% UE44-GO,which were closed to that of the epoxy zinc rich primer with 70% zinc content.The results show that UE44-GO can replace part of zinc powder in zinc-rich coatings,which is not only beneficial to improve the anticorrosive performance of coatings,but also helpful to reduce the use of zinc powder in anticorrosive coatings.This is of great significance for saving resources and protecting the environment.