The Preparation And Dielectric Properties Study Of PANI/sulfonated SEBS Composites

The rapid development of the electronics and electrical engineerings need high dielectric constant materials to fit the electronic components with functionalization and miniaturization.The traditional titanate ceramics have high dielectric constant and high piezoelectric coefficient but they are generally brittle in nature and sinter at high temperature.The polymer materials have good processability,high breakdown voltage,but low dielectric constant.So choose the appropriate filling materials to fabricate the high performance organic composites has become the development trend of dielectric materials.Many researchers have been done on ceramic-polymer composites systems that adopt ceramics as fillers.These composites have low dielectric constant even at a high loading of ceramics and the high loading will deteriorate the mechanical properties of the composites.In recent years,the composites which had polyaniline(PANI)as conductive filler material got great development.Compared with other conducting polymer,PANI has been one of the lasting hot spot in the researches on electric conductive polymers due to its diverse molecule structures,superior electric conductivity,unique doping mechanism,excellent physical properties,favorable environmental stability,low-cost raw materials and facile synthetic method.However,PANI is intractable and suffers from poor processability because of its rigid,highly conjugated backbones,which gives rise to a poor dispersibility of PANI in other polymer matrix.Therefore,the improvement of PANI disperses in polymers promises great theoretical and practical significance for various applications.Now in the preparation of composite system is mainly include mechanical mixing,solution blending and in situ polymerization.Compared with the former two methods,the in situ polymerization has the best effect.In generally,PANI synthetizes in the water phase,but the polymer is dissolved in organic solvents,so we need to add emulsifier to help PANI dispersion in the compound.The PANI particles size affected by the size of the micelle,and demulsification process makes the uniform dispersion of PANI reunion which affects the performance of the composite.In this paper,we truly achieve the in situ polymerization of PANI in polymer matrix on the basis of previous research results.We prepared different degree of sulfonated polystyrene-hydrogenated polybutadiene-polystyrene(SEBS)by'premixed method'.Then fabricated the PANI/S-SEBS composites in THF with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ)as oxidant,perchloric acid(HClO4)as the dopant in situ polymerization.In the method we achieved PANI and S-SEBS compatibility in molecular level.The PANI disperses very uniformly in the composites by the results of SEM.The composites had an ultra high dielectric constant which attributed to Maxwell-Wagner interface polarization effect.The experimental data showed that the higher degree of S-SEBS,the larger dielectric constant the composites had when the PANI content kept constant.And the higher degree of S-SEBS can reduce the dielectric loss as well because the better compatibility between PANI and S-SEBS.The dielectric constant was 1026 and dielectric loss angle was 0.58 when the composites contain 3.2%PANI at 1000Hz and room temperature while 2.2×105 and 2.2 contain 19.2%PANI.Our composites had higher dielectric constant and lower dielectric loss angle compared with the composites prepared with traditional in situ polymerization because of the well dispersion.