Fabrication And Application Of Plant Fiber Based Highly Conductive Materials With Superhydrophobic Surface

The plant fiber has the characteristic of low cost, light-weight, renewable, biodegradable, it has three- dimensional porous structure, and many active groups exist in its chemical structure, thus it has been widely used in many fields. At the same time plant fiber has strong water absorption and very weak conductivity, which restricts the application of the plant fiber in the conduction and energy materials. In this paper, the plant fiber and cellulose were used to prepare superhydrophobic surface materials and highly conductive materials. And many kinds of methods, like as coating, modification, and coupling were used to combine carbon nanotubes and other conductive polymer to prepare plant fiber based highly conductive materials with superhydrophobic surface. The mechanism and production methods of the conductivity and hydrophobicity were studied, and initially solved the mutual exclusion of conductivity and hydrophobicity, offered technological and theoretical support for the application of plant fiber in some new fields.A new type of superhydrophobic and opaque paper was obtained by modifying titanium dioxide nanoparticles and then papermaking with plant fiber. When the contents of MPS-modified-TiO2 was 13 wt%, the water contact angle of the paper arrived at 154.2°, the sliding angle <3°, showed the good property of superhydrophobicity, and got the good opacity of the paper (86.7%). The effects of reaction conditions, like as the contents of Silane coupling agents, the pH value, the grafting efficiency were studied on the impact of superhydrophobic paper. There is a lotus leaf surface similar to the micro-nano-structured of titanium dioxide on the surface of the paper.The reasons of the mutual exclusion of conductivity and hydrophobicity were system analyzed by combining the superhydrophobic and conductive mechanism of plant fiber in order to provide guidelines for the preparation of superhydrophobic surfaces. The conductivity of plant fiber mainly through the“conduction”of its combination of conductive materials, the more compact and smoother surface results the higher conductivity. While the superhydrophobicity requires the lower surface free energy, and more importantly, requires the rough microstructure on the surface, this is equivalent to the“barrier effect”of the material. Multi-walled carbon nanotubes were functionalized with mixed acid method by reflux and ultrasonic method. The yield of carbon nanotubes and the corrosion of the single CNT fiber were discussed by comparing different treating methods, lasting time, and temperature to optimize the process conditions.The silane coupling agent (Methyltrichlorosilane) was dissolved by the mixture solution of distilled water and ethanol, and the pH value was adjusted by ammonia solution. The influences of the silane coupling agent morphological and hydrophobic properties, such as the volume fraction, drying method, drying temperature, and pH value were discussed. The optimal conditions were obtained: 5 volume of distilled water and 95 volume of ethanol dissolve 1.8 volume of silane coupling agents; the solution is dried at 70℃by UV-Ozone, and the pH value is arranged from 4 to 5.Highly conductive paper materials were fabricated by combining MWNTs and PEDOT: PSS with a special unidirectional drying method. The resistance of the samples and the thickness of coating layers were smaller than those samples that had been prepared without the special drying method. When the content of the MWNTs in the solution increased, the resistance decreased. When the samples were coated with 4 mg/ml MWNTs solution that was dispersed with 1 mg/ml PEDOT: PSS, the conductivity reached 46±10 S/cm, which was one and two orders of magnitude larger the conductivity for films made with MWNTs dispersed with SDBS or PEDOT: PSS solution only. When PEDOT:PSS was used as a surfactant for MWNTs, it promoted good connection of MWNTs with the paper fibers, which caused the film surface to become very smooth and highly increased the conductivity of the samples. The superhydrophobic solution was prepared by coupling functionalized MWNTs with cellulose. Then it was used to prepare cellulose based superhydrophobic membrane by spin-coating and self assembly methods. According to the water contact angle and the SEM morphology analysis of the materials, the superhydrophobic surface can both obtained by the two methods, but the superhydrophobic property of the sample that treated by spin-coating is higher than that by self assembly method. There exists not only a large number of compact and uniform porous structures, but also numerous nano-micro structures on the surface of the sample, which reflects the more obvious characteristics of“liquid- gas- solid”phase.Highly conductive paper with superhydrophobic surface was prepared with the combined process of Meyer-rod-coating by unidirectional drying and spin-coating by UV-Ozone drying (MethodⅠ). And cellulose based highly conductive membrane with superhydrophobic surface was prepared with mixed process of coupling functionalized MWNTs with cellulose and spin-coating by UV-Ozone drying (MethodⅡ). The results showed that the superhydrophobicity increased with the coating layers increased, but at the same time the conductivity decreased when the samples were treated by MethodⅠ.while when it prepared by MethodⅡ,the superhydrophobicity and conductivity of the samples increased with the coating layers increased, initially solved the mutual exclusion of conductivity and super- -hydrophobicity.