Bacterial Cellulose as a Template for the Formation of Polymer/Nanoparticle Nanocomposite

In this paper, we investigate a novel method using bacterial cellulose (BC) as template by in situ method to prepare BC/silver nanocomposites. We first introduce sonication procedure during immersion and reduction reaction process to make sure that the silver nanoparticles can be formed and distributed homogeneously throughout the whole bacterial cellulose network. The BC/silver nanocomposites were confirmed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). To examine the effect of varying solution concentrations on silver nanoparticles formation, the concentration of AgNO₃ solution was increased from 0.01 M to 0.05 M and Ag⁺-ions were reduced by the same concentration of NaBH₄. The effects of time and frequency of sonication on BC/silver nanocomposite preparation were also investigated by varying sonication time from 10 min to 60 min and sonication frequency from 20 kHz to 60 kHz. Compared with an ordinary process, ultrasound seems to be an effective way for ions to penetrate into BC and thus the weight percent of silver nanoparticles can be increased. Combined with TGA result, the weight percent of silver nanoparticles can be improved from 8.9% to 31.7% with simple sonication procedure performed by the same preparation condition. However, the average size of silver nanoparticles is around 15 nm, which is bigger than ordinary process. This may be due to the aggregation of small nanoparticles, especially at high AgNO₃ concentration.