Preparation Of Polyaniline/nanocrystalline Cellulose Composite And Its Application In Coated Electro-conductive Paper

Electro-conductive paper,known as a new kind of functional paper,inheriting the advantages of lignocellulosic paper such as light weight,rich raw materials and environmental protection,has shown great potential in diversified applications,e.g.,electronic devices,energy storage materials,antistatic and electromagnetic shielding materials.Actually,plant fiber is non-conductive,and the electro-conductivity mainly depends on the addition of electro-conductive fillers such as carbon-based materials,metals and their oxides and conductive polymers.Among the electro-conductive fillers,the conductive polymers with high electrical conductivity and desired stability have aroused wide concern in the research of paper-based material.In the present paper,the polyaniline(PANI)/nanocrystalline cellulose(NCC)composite was prepared by chemical oxidation polymerization,and subsequently used as electro-conductive pigment for the preparation of coated electro-conductive paper via pigment coating process.The physical and chemical properties of the PANI/NCC composite and its application potential in the coated electro-conductive paper were systematically studied.Firstly,the PANI/NCC composite was prepared by the chemical oxidative polymerization method,and the suitable process conditions were acquired.At a desired temperature and reaction time,when the molar ratio of ammonium persulfate(APS)to aniline(An)was close to 1:1 and the NCC content was 4 wt%(relative to the amount of An),the electro-conductivity of PANI/NCC composite reached 281 S·m-1.In addition,the images of polymerization products and the microscopic morphology showed that NCC was wrapped with PANI particles and the dispersion of PANI particles was generally improved.The results of infrared spectroscopy and X-ray diffraction analysis demonstrated that the characteristic peaks of PANI appeared in the composite,indicating that PANI maintained its structure and crystal form,while the strength and position of these peaks were affected by various contents of NCC.Thermogravimetric analysis results provided evidence that the addition of NCC could reduce the thermal stability of the obtained PANI/NCC composite.Secondly,the electro-conductive coating was prepared by using the PANI/NCC composite as electro-conductive pigment,supplemented by kaolin,montmorillonite,adhesive,dispersing agent and other auxiliaries.The steady rheological behavior and dynamic viscoelasticity of the as-prepared coatings with different ratios of pigments and various contents of NCC were systematically studied.The results showed that the increase of PANI/NCC composite ratio would improve the viscosity and dynamic viscoelasticity of the coating system and the contents of the kaolin and montmorillonite had a comparatively limited effect on the rheological behavior of the coatings.Moreover,the addition of NCC was prone to alleviating the mass aggregation of PANI particles and reduced the apparent viscosity of the coating system.Finally,the electro-conductive coating was coated on the lignocellulosic paper,the electro-conductive and mechanical properties,micro-morphology and thermal stability of the coated paper were investigated.The results showed that the electro-conductivity of the coated paper mainly depended on the content of PANI/NCC composite and also affected by the action of other particles in the coating system.Specifically,the coated paper under the action of montmorillonite was better than the equal share of kaolin.Furthermore,the addition of NCC could improve the electro-conductive and mechanical properties of the coated paper.Compared with the coated paper without NCC,the longitudinal tensile index of the coated paper containing 2 wt%NCC and 8 wt%NCC was increased by 9.8%and 15.7%,respectively,and the longitudinal folding resistance was increased by 11.7%and 33.3%,respectively.The microscopic morphology and thermogravimetric curves further indicated that the fibers of the base paper were completely covered by coating,and the thermal stability of the base paper was slightly improved as a function of coating process.