Preparation And Properties Of The Superhydrophobic And Wear-resistant Coating Based On Benzoxazine/Epoxy Group

Superhydrophobic materials have broad application prospects in self-cleaning,waterproofing and anti-icing.However,at the same time,there are disadvantages such as poor wear resistance and poor adhesion to the substrate,which severely limits its application.It is important to improve the wear resistance of the superhydrophobic coating and the adhesion of the coating to the substrate.In this paper,the benzoxazine with certain hydrophobic properties was selected as the main material from the substrate of superhydrophobic materials.The benzoxazine was modified by the alicyclic epoxy resin with good film formation and strong adhesion.A matching benzoxazine/epoxy resin（BE）blend coating.The properties of curing mechanism,heat resistance,surface properties and adhesion were analyzed.The research on the curing mechanism shows that the benzoxazine/epoxy resin is a thermal ring-opening reaction of benzoxazine,and then the copolymerization reaction of benzoxazine with epoxy resin.The BE system was tested for thermal performance and the system exhibited good heat resistance.T_5%temperature is above 300℃.The test system for the surface properties of the BE system showed a low surface energy.The calculated results showed that the surface energy of the benzoxazine:epoxy resin 9:1 BE9 system was at least 27.35 mJ/m².The increase in the content of benzoxazine resulted in a gradual increase in the water contact angle of the BE system,from 86.5°in the BE5 system to 90.3°in the BE9 system.Adhesion studies show that the improvement of adhesion of epoxy resin to the system is not obvious,and the adhesion of BE system can only reach level Ⅱ.For benzoxazine/epoxy resin（BE）blends,the epoxy resin has a certain toughening effect on the benzoxazine resin.From the cross-section scanning of the blend system,From the cross-section scanning of the blend system,it can be seen that the system changes from a smooth brittle fracture surface to a tough fracture surface with folds.To further enhance the adhesion of the coating,a superhydrophobic coating is prepared.The BE system was used as the matrix,and the mesoporous SiO₂ was used as the filler for the micro-nano structure of the organic-inorganic interpenetrating network.The benzoxazine/epoxy resin/mesoporous SiO₂（BES）system with different ratios was prepared.The properties of curing mechanism,surface properties,abrasion resistance and adhesion were studied.The results show that the addition of mesoporous SiO₂ acts as an active catalyst in BES system,The peak temperature of curing of BES system has a forward shift of 5℃ compared with BE system.The water contact angle test results of BES system show that the water contact angle of the system increases with the increase of mesoporous SiO₂content.When the mesoporous SiO₂ content reaches 15 wt%,the BES system reaches the superhydrophobic state,and the contact angle reaches 164.4°.When the mesoporous SiO₂content is 20 wt%,the contact angle is at most 167.5°.Adhesion tests show that the addition of mesoporous SiO₂ can greatly improve the adhesion,and the adhesion level can reach level I.The wear resistance test was carried out on the coating which reached the superhydrophobic state.The superhydrophobic coating was excellent in abrasion resistance,the BES-25 system can still reach a coating angle of 150°after 100 cycles.The BES system coating curing reaction temperature is too high,in order to reduce the curing temperature of BES system,imidazole is added to BES system to modify,to prepare benzoxazine/epoxy resin/imidazole/mesoporous SiO₂（BEIS）system coating.The properties of the BEIS system coating curing mechanism,heat resistance,contact angle,wear resistance and corrosion resistance were studied.Curing mechanism studies show that after the addition of imidazole,the ring opening mode of benzoxazine becomes cationic ring opening during the curing reaction compared to the BES system coating.The surface properties were tested.The mesoporous SiO₂ content reached 15 wt%and the system contact angle reached 154.68°.The abrasion resistance test showed that the BEIS wear resistance was enhanced by 5-10 cycles compared to the BES system.Adhesion testing indicates that the adhesion of the BEIS system can reach level Ⅰ.Studies have shown that epoxy resin has a certain toughening effect on benzoxazine,but the improvement of adhesion is limited and can’t reach level Ⅰ.The addition of mesoporous SiO₂ can significantly improve the adhesion between the resin and the substrate,so that the adhesion level of the coating reaches level I.The pore structure of mesoporous SiO2 allows the coating to construct an organic-inorganic interpenetrating network structure,and there is a hierarchical self-similarity in the micro-nanostructure of the coating.This special structure is the reason for the excellent performance of the system.