Preparation And Characterization Of Self-healing Epoxy Acrylate Based On Host-guest Chemistry

Polymers and composites have been widely used for their excellent properties.However,materials might appear microcracks and other damages during their processing and use,resulting in potential risk and decreasment of service life Self-healing materials emerge in this case.Self-healing materials based on host-guest chemistry have been widely investigated in recent years due to their facile synthesis,mild repair conditions and multiple healing property et al.However,current work on self-healing materials based on host-guest chemistry mostly focus on hydrogel functional materials,which have extremely low mechanical properties and cannot be used as structural materials.Epoxy as a representative of thermosetting resins is often used as the resin matrix of advanced composites.In this paper,host-guest intereaction was introduced into the cross-linked structure of epoxy acrylate resin for the first time and constructed an intrinsic self-healing epoxy acrylate resin.This research has important theoretical and practical significance to realise the self-healing of thermosetting polymers.?-cyclodextrin is often used as host molecule,which can form host-guest inclusion complex with a variety of molecules.In the thesis,azobenzene and ?-cyclodextrin were introduced into the crosslinking point of epoxy acrylate resin simultaneously.Because of photo/thermal-induced cis-trans isomerism of the azobenzene group,the reversible binding of ?-cyclodextrin and azobenzene can be achieved,so as to realize the self-healing of epoxy acrylate resin.Using the principle of molecular design,azobenzene and ?-cyclodextrin derivatives containing C=C were synthesized.After the host-guest intereaction,the bifunctional host-guest inclusion complex is introduced into the epoxy acrylate.Under UV light triggering,C=C of the inclusion complex can participate in the photocuring reaction of the epoxy acrylate,and form the host-guest cross-linked epoxy resin.This method doesn't need to redesign the molecular chain of resin matrix,and has the advantages of simple and reliable.The results showed that the epoxy acrylate resin with ?-cyclodextrin inclusion complex has a good self-healing ability.When the content of inclusion complex is 5%,the tensile strength of the epoxy resin film before healing is 14.7 MPa.After 20 minutes of restoration,the maximum healing efficiency of 62.82% can be achieved,showing a rapid repair rate.In addition,the tensile strength after four healing processes can still maintain 9.06 MPa,which has a good ability of repeated healing.Based on the above research,a graphene/?-cyclodextrin-azobenzene host-guest inclusion complex containing C=C was designed and prepared,and then the inclusion complex was introduced into the epoxy acrylate via copolymerization reaction.Due to the macromolecular anchoring effect of the graphene sheet,the cured epoxy acrylate can form a cross-linked structure based on the host-guest chemistry.The intrinsic self-healing of the epoxy resin can be achieved by controlling the reversible binding of the host-guest inclusion complex.The results show that the graphene/epoxy film has the best self-healing property when the content of the modified graphene nanosheets is 10%.At this point,the healing efficiency was 79.2%,and the tensile strength after healing was 16.5 MPa,which is a relatively high level in the intrinsic self-healing epoxy.The graphene/epoxy film also has the ability of repeated healing.After the four scratch-healing cycles the tensile strength remains 14.3 MPa,showing stable ability.