The induction of poly(vinylidene fluoride) electroactive phase by modified anodic aluminum oxide template nanopore surface

The desired electroactive beta and gamma phases of poly(vinylidene fluoride) (PVDF) nanostructures are rarely obtained through wetting methods using anodic aluminum oxide (AAO) as a template. Further and systematic studies on the corresponding induction mechanism are also lacking. Herein, we designed and fabricated PVDF nanowires using a solution wetting method with pristine and modified AAO templates. The morphology and crystalline structure of the PVDF nanowires were characterized by SEM and micro-FTIR respectively. Then, the induction mechanism was investigated by AFM, FTIR, TGA and contact angle measurements. It is found that the polarity of the solvent and the surface hydroxyl groups on the template nanopores both have an inductive effect on the polar phase. After the oxygen plasma treatment, the proportion of b phase of the PVDF nanowires becomes higher although the total polar phase content remains the same. This is attributed to the high polarity of the nanopore surface and regular arrangement among the hydroxyl groups. The polar phase content of the PVDF nanowires increases from 40% when prepared by the pristine template to 71% when prepared by a 3-aminopropyltrimethoxysilane (APMS) modified template. It can be explained that more interaction points and stronger interactions result in the formation of more of the electroactive phase.