Research On Fabrication Of Nano-modified And Nitrogen-doped Graphene And Its Composites With Polymers

Functional polymer composites have been widely studied because of their diverse functions and flexibility.Graphene is considered to be very suitable as a functional component of polymer composites due to its excellent performance in thermal,mechanical,electrical and other aspects.However,in many cases the excellent properties of graphene have not been sufficiently excited in silicone composites and polyaniline-based supercapacitor electrode materials.For the silicone composites,the reason can be summarized into two aspects: First,graphene is easy to stack,agglomeration and graphitization due to van der Waals force,making it difficult to disperse in silicone composites.Second,graphene lacks affinity or compatibility with organic silicones,or lacks chemical or physical interactions with such polymers,leading to unsatisfactory interface adhesions and making it difficult to adapt the stimulus or changes of external environment.For the graphene-polyaniline-based supercapacitor electrode materials.One of the unsolved problems is that the surface of the graphene is covered or blocked by a large amount of polyaniline,resulting in a reduced exposed specific area of graphene to the electrolyte ions and making the electric double layer capacitor not been fully used.The proper functional modification of graphene can improve the compatibility and dispersibility of graphene in polysiloxane,as well as the electrochemical properties of graphene as an electrode in polyaniline-based supercapacitors,which will better excite the excellent thermal,mechanical and electrical porperties of grahene.In this paper,silica was used to modify the graphene/silicone rubber interface and graphene/polyaniline,then highly dispersed graphene/silica/silicone rubber composites and pore-structured graphene/silica/ polyaniline composites were prepared.The thermal conductivity,mechanical properties of graphene/silica/silicone composites and the electrochemical properties of graphene/silica/polyaniline composites were studied.In addition,nitrogen-doped graphene was prepared and the electrochemical performances of nitrogen-doped graphene as a supercapacitor electrode were studied.The main contents and results of research are as follows:1.The interface of graphene/silicone rubber was nano-modified,the process is as follows: Graphene / silica composites were prepared by the sol-gel method,then the graphene/silica/silicone rubber composite was obtained by adding the graphene/silica directly to silicone rubber without solvents.The thermal and mechanical properties of graphene/silica/silicone rubber composites were studied.The experimental results showed that compared with graphene/silicone rubber composites,the graphene/siica/silicone rubber composites showed better mechanical and thermal properties.2.In order to better exhibit the electrical properties of graphene in the polyaniline-based supercapacitor,silica with good chemical stability was introduced into graphene.Then graphene/silica/polyaniline(rGESP)ternary composite was prepared by in situ polymerization method,and their electrochemical properties were studied.The experimental results showed that graphene / silica / polyaniline exhibited improved electrochemical performances than simple graphene,polyaniline and graphene/polyaniline.3.Graphene was doped with nitrogen atoms to improve its electrochemical performances.The nitrogen-doped graphene with nitrogen content of 5.08% was prepared by using graphene oxide as raw material and urea as nitrogen source,and its electrochemical performances were studied.The experimental results showed that nitrogen-doped graphene exhibited better electrochemical performances than graphene.