Piezoelectric property of hot pressed electrospun poly(γ -benzyl-α, L-glutamate) fibers

Since the 1960s, the piezoelectricity in biopolymers (e.g. proteins and polynucleotides) has attracted considerable scientific attention. In particular, poly(glutamate)s have been one of the most popular targets for this research due to their well-defined helical structure and permanent polarity along the helical axis. To date, films of poly(glutamate)s have been shown to exhibit piezoelectricity only in shear mode (d ₁₄), mainly due to the limitation in fabricating electrically poled polymer samples. This paper describes a combined electrospinning and hot press method that allows production of poled poly(γ -benzyl-α,Lglutamate) (PBLG) films with piezoelectricity in all d ₃₃, d ₃₁ and d ₁₄ modes for the first time. It is found that this PBLG film belongs to the matrix structure of C _∞v group, which is the same as that of poled PVDF film. The moderately high piezoelectric coefficients in both d ₃₃ and d ₁₄ modes as well as their thermal stability make the poled PBLG film an excellent candidate for use in flexible transducers and small energy harvesting devices.