Boosting dielectric and mechanical functionality in electrospun PVDF through cellulose nanocrystal-mediated β-phase formation

The growing demand for sustainable and multifunctional materials in flexible electronics has driven research into polymer-based nanocomposites reinforced with biofillers. This study investigates the dielectric, ferroelectric, mechanical, and thermal properties of electrospun polyvinylidene difluoride (PVDF) nanocomposites incorporated with cellulose nanocrystals (CNCs) as a renewable bio filler. PVDF/CNCs nanofibers were fabricated via electrospinning with CNCs loadings of 0.5, 1, and 1.5 wt%. Morphological characterization confirmed uniform dispersion of rod-shaped CNCs within the PVDF matrix, while FTIR analysis demonstrated a significant enhancement of the electroactive β-phase content, attributed to the nucleating effect of CNCs which promote polymer chain alignment and dipole orientation. Thermal analysis revealed a modest improvement in thermal stability with increasing CNCs content, particularly up to 1 wt%. Mechanical testing showed remarkable enhancements, with tensile strength increasing by approximately 140 %, Young's modulus by 110 %, and elongation by 95 % at 1 wt% CNCs loading, evidencing CNCs reinforcing effect. Dielectric measurements indicated an increase in dielectric constant from 5.9 (pure PVDF) to 9.4 with low dielectric loss, reflecting enhanced polarization due to interfacial interactions and β-phase promotion. Polarization-electric field (P–E) loop results further confirmed improved ferroelectric behavior, with remnant polarization increasing alongside CNCs concentration, signifying better dipole alignment and phase purity. The integration of CNCs as a sustainable nanofiller enhances PVDF's structural and functional attributes, combining mechanical robustness with superior dielectric and ferroelectric performance. These lightweight and flexible PVDF/CNCs nanocomposites show strong promise for applications in flexible electronics such as energy harvesting and sensors, aligning sustainability with high performance.