Development and analysis of a novel PVDF membrane with higher content of β phase

Poly(vinylidene fluoride) (PVDF) has been widely used in flexible sensors, nanogenerators, and other fields because of its good physical properties. The influence of the content of β phase in its crystalline form has a great influence on its performance. In order to obtain PVDF membrane with high β phase content, electrospinning is an important technology. However, the parameters of electrospinning conditions are numerous and difficult to optimize. In this work, response surface methodology, a method to solve the relationship between input (test variable) and output (response or experimental index) of complex system by using the comprehensive experimental technique of statistics, was first used to analyze the effect of electrospinning conditions on the content of β phase and to optimize the optimum conditions for obtaining high content of β phase. Breifly, the Plackett–Burman design (PBD) was first implemented to screen out the three most significant factors affecting the β phase content increase from 10 complex factors. Then, the steepest ascent was used to determine the central point of the values of these three factors. After that, the Box–Behnken design (BBD) was selected to establish the model and conduct response surface analysis to obtain the optimum parameters of electrospinning with high β phase content in theory. Finally, the electrospun PVDF film with high β content (FT-PVDF) was obtained by electrospinning with theoretical parameters, and characterized by FTIR, XRD, DSC, and piezoelectric properties. Compared with pure PVDF electrospun films, it was confirmed that FT-PVDF had high β content consistent with prediction, and showed better performance than PVDF.