Electrospun Polymer Composite Nanofiber Containing Uniformly Dispersed Graphene

Electrostatic spinning using high voltage power is the preparation of polymer nanofiber, which has a lot of advantages, such as: large surface area, high porosity, etc. Graphene is considered the monolayer carbon atoms of two-dimensional slice layer honeycomb lattice structure of new materials, and it has found the most thin and rigid inorganic nanomateria in the world. Its stability of the lattice structure of carbon atoms have excellent electrical conductivity, excellent transmission of light. Because of graphene with such outstanding features, studies of graphene/polymer composite nanomaterials is undoubtedly one of the hot research topic in the field of materials. However, synthesis of graphene and its application in most polymer have encountered a lot of problems, because of the laminated structure is easy to gather together a widespread reunion, and it has resulted in a uniform dispersion of graphene in polymer matrix is very poor. How to solve the grapheme dispersed in polymer matrix, and improve the graphene layers structure and interface combined with polymer matrix problems. The results show that it is the scientific community has been trying to solve the problem. This project thesis aiming at these problems, on the basis of existing research, a large number of graphene was synthesized with chemical method, through the nanocrystalline cellulose assist dispersion reduction of graphene oxide, made uniform and stable graphene layer structure of water dispersion. Then added the grapheme to the polymer matrix with method of blending, preparation of graphene/polymer( thermoplastic polyurethane and polycaprolactone) composite nanofibers by electrostatic spinning. This kind of composite nanofibers, is expected to be flexible electrode, super capacitor, pressure sensor, medicine and mading outstanding contributions in other fields. In this paper the research content is as follows:(1) We use the modified Hummers method that prepared graphene oxide. By hydrazine hydrate reduction preparation of graphene. Characterization structure and properties of graphene and graphene oxide by electron microscopy, Raman spectroscopy, Fourier infrared, X-ray diffraction and Elemental analysis and so on.(2) Through the self-made nanocrystalline cellulose auxiliary dispersed reduction graphene oxide, and made dispersed uniformly and stable graphene/nanocrystalline cellulose water dispersion. Then using the method of blending preparation of polyurethane composite membrane. The thermoplastic polyurethane composite nanofibers containing uniformly dispersed reduced graphene oxide(rGO) and nano-crystal cellulose(NCC) were fabricated by electrospinning. Transmission electron microscope(TEM), scanning electron microscope(SEM) and laser particle analyzer were used to characterize the morphology and structure of grapheme, nano-crystal cellulose and composite nanofibers. Universal tensile instrument, rmogravimetric analysis(TGA) and optical contact angle tester were used to analyze the mechanics performance, thermal performance and hydrophilicity of nanofiber membrane. The results show that the morphologies and mechanical properties of the nanofibers are the best when the content of graphene was 1.5wt%. In this case, the maximum tensile strength of composite nanofibers(31.98 MPa) increased by 303.79% with respect to the maximum tensile strength(7.92 MPa) of the pure TPU nanofiber membrane. In addition, the thermal stability and hydrophilicity of the composite nanofibers increases with the increasing of the content of rGO and NCC. The excellent performance of composite membrane will be flexible electrode, pressure sensor, biological medicine, etc, has wide application prospect.(3)Using the self-made nanocrystalline cellulose auxiliary dispersed reduction graphene oxide, and made dispersed uniformly and stable graphene/nanocrystalline cellulose water dispersion to made the graphene/nanocrystalline cellulose/polycaprolactone Composite spinning solution, whicn is water-in-oil emulsion. Preparating the graphene/nanocrystalline cellulose/polycaprolactone composite nanofibers using electrostatic spinning. Transmission electron microscope( TEM), scanning electron microscope(SEM) and laser particle analyzer were used to characterize the morphology and structure of composite nanofibers. Universal tensile instrument, rmogravimetric analysis(TGA) and optical contact angle tester were used to analyze the mechanics performance, thermal performance and hydrophilicity of nanofiber membrane. The results show that the morphologies and mechanical properties of the nanofibers are the best when the content of graphene was 1.5wt%. In this case, the maximum tensile strength of composite nanofibers(21.25 MPa) increased by 70% with respect to the maximum tensile strength(12.5 MPa) of the pure PCL nanofiber membrane. With the increase of the content of G in photo, graphene/nano crystalline cellulose/poly(caprolactone composite nano fiber hydrophilic significantly increased, the contact Angle is 123.43 °(rGO content 0%) down to 86.54 °(rGO content of 3.5%). The addition of graphene does improve some properties of the polymer nanofibers, but the improvement of the conductivity of nanofibers is not ideal.We will focus on the future research work to improve the conductivity of polymer nanofibers, to make the polymer composite nanofibers are applied in more fields.