Key factors affecting the piezoelectric response of poly-L-lactic acid electrospun fibers

Abstract

Piezoelectric materials are increasingly explored as self-powered platforms in regenerative medicine and tissue engineering. Poly-L-lactic acid (PLLA) is particularly promising for biomedical applications due to its biodegradability, especially when processed via electrospinning which allows simultaneous fiber alignment and chain orientation. However, the mechanisms that enable and enhance the piezoelectric properties of PLLA remain insufficiently understood. This study employs a design-of-experiment approach to systematically examine the effects of chiral purity, molecular weight, and crystallinity on the resulting piezoelectric response of PLLA.

In this work, highly aligned electrospun microfibers were successfully fabricated, revealing a direct relationship between the piezoelectric response and the processing method due to dipole orientation along the polymer chains through electrospinning. The piezoelectric properties were strongly influenced by crystallinity and chain orientation. The most crystalline sample (52 %) is characterized by high chiral purity and lower D-isomer content, showing the highest piezoelectric response, while samples with higher D-isomer content exhibited the lowest crystallinity and performance. Thermal treatment at 100 °C enhanced the crystallization of the oriented metastable phase in the as-spun fibers, resulting in increased melting temperature. Samples initially exhibiting amorphous or metastable phases displayed a significant increase in crystallinity and piezoelectric response following thermal treatment, highlighting the potential of controlling crystallization for optimizing piezoelectric performance in biomedical applications.