Electric field-assisted patterning of cellulose whisker-reinforced polymer nanocomposites

Cellulose whiskers (CWs) have attracted a lot of interest due to their potential to improve the mechanical and piezoelectric response of polymers. In addition, CWs are high aspect ratio particles; by aligning them in polymers, improved and anisotropic physical properties could be achieved. In a previous study, we investigated alignment of microscale CWs in silicone oil. OMs showed that alignment of CWs increased with frequency up to 500 mHz and then decreased. In the current study, we investigate the alignment of CWs in a solution of PVAc and DMF. CWs were dispersed as small bundles (<50μm). An optimum alignment with chain formation was achieved at 150Vpp and 50 KHz. In a separate study, we investigated the conditions to prepare composites of unfunctionalized and functionalized CWS in PVAc. Resulting composites were transparent and flexible. In order to achieve dispersion at the nanoscale, the CWs were treated with sulfuric acid, resulting in sulfate group functionalization. SEM showed the functionalized CWs were well dispersed, where the bundle size was 60 nm. Next, we will process aligned CW/PVAc composites by thermally curing the structure in presence of electric field. Random and aligned CW/PVAc composites will be characterized and compared to the above microcomposites. The goal is to achieve a flexible piezoelectric composite.