Preparation And Characterization Of Bacterial Cellulose/Polypyrrole Flexible Conductive Composite Membrane Material

Conducting polymers have been widely used in the fields of bateries,chemical sensors, metal corrosion, electronic device and electromagnetic interference shielding devices for their special structure, attractive physical and chemical properties. Polypyrrole (PPy) is one of the most common conducting polymers due to its low-cost preparation, high conductivity, non-toxicity and good stability. But the low solubility, infusibility and low mechanical property of PPy restrict its processing and applications. The main way to avoid these drawbacks is the preparation of PPy composite materials.Bacterial cellulose (BC) is a new kind of natural biological nanomaterial. BC membrane can be used as the matrix to prepare composite materials with other functional materials with specific shape and nano-sized by in situ synthesis, due to its ultrafine network architecture with a distinct tunnel and pore structure, high specific surface area with a great deal of hydroxyl groups. Therefore, BC membranecan be composited with many materials and obtain many kinds of new attractive functional materials.BC/PPy flexible conductive composite membrane materials were prepared by in situ chemical synthesis. The influencing factors of composite conductivity were investigated. Afterwards, hydrophobizing process was taken on the surface of BC/PPy membrane, and its properties were investigated. The worksare introduced as follows in detail:(1) BC/PPy membranes were prepared and discussed. The influence of monomer concentration, reaction time, the ratio of oxidant and monomer, doping agent on membrane conductivity were studied. The conductivity of nanocomposite reached0.16S/cm when the monomer concentration was0.07mol/L, the reaction time was2h, the mole ratio of oxidant and monomer was2.3. The conductivity of membrane could reach0.27S/cm by an external ice-bath (0℃). Doping sodium dodecyl benzene sulfonate (SDBS) could not enhance the conductivity.(2) The influence ofalkali pretreatments and TEMPO-mediated oxidation of BCwere studied.Then, conductive membrane based on pretreated bacterial cellulose was prepared and its properties and mechanism were investigated. The results revealed that the conductivity of membrane was increased by using alkali swelling to pretreat BC. The conductivity of membrane could reach2.45S/cm by an external ice-bath. The TEMPO-mediated oxidation of bacterial cellulose had little contribution to enhance conductivity of membrane.(3) Hydrophobic processing was taken on the surface of BC/PPy membrane by polysiloxane, and its properties were investigated. The results revealed that the roughness of membrane and the contact angle (CA) increased along with the rising concentration of monomer. The biggest CA of membrane could reach160.3°. Surface treated using polysiloxane had little influence on conductivity of membranes according to the electric property analysis. Furthermore, electromagnetic shielding performancewas observed in the hydrophobic conductive membranes.