Silver nanoparticles filled in bacterial cellulose/Poly(vinylidene fluoride) nanocomposite films for touchscreen applications

Abstract

Flexible piezoelectric films of bacterial cellulose(BC)/poly (vinylidene fluoride) (PVDF) were successfully prepared via solution casting and hot compression method. The various weight percentage of BC (2.5-15 wt.%) was incorporated into PVDF matrix using dimethylformamide (DMF) as a solvent and dispersing liquid to study the basis of piezoelectric touch sensor. The combination of β crystalline phase and α crystalline phase of BC/PVDF blend films were presence with the higher amount of β crystalline phase. According to the application of touchscreen, BC2.5PVDF97.5 was selected as a based nanocomposite to develop further due to its highest percentage of transmission at the wavelength range of 400 nm - 750 mm which is the range of visible light compared with the other blends. In order to achieve high dielectric properties for piezoelectric touch sensor, silver nanoparticles (AgNP) was introduced to enhance the dielectric constant of the blend. AgNP has high ability to create an interaction with hydroxyl groups in BC and fluorine atoms in PVDF chains which can generate the dipolar polarization. The highest dielectric constant was observed in 0.5 wt.% of AgNP in nanocomposite film which can yield to higher dielectric constant about 4 times compare with blend film. The incorporated of BC exhibited an improving of thermal stability and dynamic mechanical properties, but decreasing the transmittance percentage of visible light. In contrast, AgNP may agglomerate which can obstruct the light not to pass through the nanocomposite easily, resulted to the worse transmittance percentage of visible light.