Strategies to improve piezoelectric and mechanical properties of BNNS/PDMS composites

Flexible piezoelectric composites exhibit great potential for applications in energy harvesting, structural health monitoring, and intelligent infrastructure. In this study, boron nitride nanosheets (BNNS) and carbon nanotubes (CNT) are incorporated into polydimethylsiloxane to develop piezoelectric composites. The effects of co-solvents containing ethyl acetate, acetone, and tetrahydrofuran (THF) are evaluated experimentally, and molecular-dynamics simulations are performed to elucidate the microscopic mechanism. THF produces the most uniform filler dispersion, resulting in the highest piezoelectric coefficient ( d 33 = 3.27 pC/N) and enhanced mechanical properties (tensile strength of 3.62 MPa and elongation of 267 %) in these composites. Increasing BNNS loading enhances the d 33 and tensile strength, but reduces the elongation at break. Optimal CNT loadings (1 wt%) reveal an increased d 33 of 5.27 pC/N, which is 37.6 % higher than that of samples without CNT, though the mechanical properties are slightly degraded because of localized agglomeration. Key steps in the preparation process are identified and optimized to enhance filler dispersion and interfacial bonding. The samples prepared via the optimized process exhibit competitive d 33 (16.6 pC/N), remarkable output voltage (16.55 V), and improved tensile strength (3.86 MPa). The synergistic effects of co-solvents, hybrid fillers, and process optimization provide practical strategies for designing flexible piezoelectric composites.