Electrical Conductivity and Optical Transparency of Bacterial Cellulose based Composite by static and agitated methods

Abstract

Bacterial cellulose (BC) is an environmental friendly material composed of pure cellulose, and many researchers have suggested its potentials to be extended to various applications in fields such as medical, beauty, clothes, diaphragm, food and so on. The main purpose of this study was to investigate electrical conductivity and optical transparency of BC based composite through modification structure of BC by changing cultivation speed. BC by static and agitated cultivation methods evaluated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) and Brunauer–Emmett–Teller (BET). From these results indicated that bacteria synthesize cellulose with different diameter of fiber from 27.76 ± 4.05 at static cultivation to 20.62 ± 3.30 (nm) at agitated cultivation. And surface area increased about twice times due to centrifugal force. The three-dimensional BC network served as a nanostructured substrate for ionic conducting polymer (ICP). ICP synthesized with varied contents of salt. The electrical conductivity of BC/ICP composite was verified by surface resistivity and volume resistivity. By enhancing ICP on BC leaded to the improvement in electrical conductivity than pure BC which is insulator. Moreover, the electrical conductivity of BC/ICP composite improved rapidly by BC with high agitated cultivation speed through filling more ICP due to surface area increased. BC fibers are invisible due to its diameter was less than a visible light wavelength. However, a dried BC is opaque because the diameter of fibers is increased due to microfibrils of BC collapsed and piled on each other. Also, the pores inside BC lead to significant light scattering. To enhance the optical transparency of BC based composite, the transparent materials fill in these pores in BC nanostructures to prevent the fibers aggregation, which affect light scattering. BC/ICP composite has improvement about 6 times than pure BC in the optical transparency. These results indicated that pores within BC, occupied by ICP, prevented light scattering. This electrically conductive and optical transparent nanocomposite can be useful in various applications requiring biocompatibility, electrical conductivity and optical transparency.