Preparation And Properties Of Polybutadiene-Based Dielectric Elastomers With High Dielectric Constant And Low Dielectric Loss

Dielectric Elastomer is a smart soft material that can deform under the excitation of an external electric field and realize the mutual conversion between mechanical energy and electrical energy.It has the advantages of light weight,large deformation,fast response speed,and high energy density,so it has broad application prospects in the fields of artificial muscles,flexible robots and medical equipment.However,at present,the dielectric elastomer materials have problems of high driving voltage and high dielectric loss,which limit their further development in the fields of medicine and bionics.In this paper,polybutadiene dielectric elastomer with large deformation is carried out by using mercapto-ene click chemistry,and the relationship between the grafted side chain structure and material properties is systematically studied.A new type of dielectric elastomer material with dielectric constant,low dielectric loss and large deformation were developed.First,thioglycolic acid was successfully grafted on polybutadiene elastomer by mercapto-ene click chemistry,and the effect of grafted thioglycolic acid on the mechanical and dielectric properties of polybutadiene elastomer was systematically studied.The results show mechanical properties of polybutadiene elastomers have been greatly improved after being grafted by thioglycolic acid.The elastic modulus by 7.5 times,and the breaking strength increase by 3 times.Importantly,the dielectric constant of polybutadiene has also been significantly increased from 2.5 to 4.2 under applied electric field with 1kHz.Followed Ethyl thioglycolate,butyl thioglycolate and isooctyl thioglycolate were successfully grafted on the main chain of polybutadiene by the same method,and the effect of polarity on the dielectric properties was investigated.The dielectric constant of the material increases while the rising trend of the loss tangent is suppressed,with decreasing of polarity in the order of thyl-thioglycolate,butylthioglycolate and isooctyl-thioglycolate.So that effectively suppresses the heat generation of polybutadiene in the electric field.After grafting butyl thioglycolate,the maximum driving deformation of the material reaches 24.5%,and when the content reaches 15wt%,the maximum driving deformation is 9.2%under the electric field strength of 30kV/mm.After grafting isooctyl-thioglycolate,the elastic modulus of the material is further reduced.When the content reaches 8.6wt%,the material achieves a driving deformation of 8.56%under the electric field strength of 30kV/mm.Finally,the quadruple hydrogen bond was successfully introduced into the main chain of low molecular weight polybutadiene,to realize self-healing.The mechanical experiment found that the material can still maintain 80%of the original strength after repeated fracture recovery at room temperature,which provides ideas for the potential reuse of polybutadiene materials and further broadens their application field.