Carbon nanotube reinforced flexible multifunctional regenerated cellulose films for nonlinear optical application

Abstract

Flexible regenerated cellulose/multiwalled carbon nanotube (RC–CNT) composites were successfully fabricated using a simple solution blending technique. The influence of functionalized multiwalled carbon nanotubes (f-CNTs) on the mechanical, electrical, thermal and optical properties of the regenerated cellulose was evaluated. Field emission scanning electron microscopy (FESEM) confirmed the uniform integration of f-CNT into the regenerated cellulose (RC) matrix. The tensile results indicated that the mechanical properties of the RC film increased considerably with f-CNT loading. The composites with 1.0 wt% f-CNT content (RC–CNT1.0) showed 60% increase in Young's modulus and 40% increase in elongation at break in combination with 50% increase in toughness, compared with RC film. The measured electrical conductivity of the composite film (RC–CNT1.0) was 6.2 × 10⁻⁴ S cm⁻¹, which is significantly higher than that of the RC film (6.8 × 10⁻¹² S cm⁻¹). Improvement in conductivity as well as dielectric permittivity values of the RC–CNT composites can be attributed to the unique network structure of f-CNT in the RC matrix. The RC–CNT composites showed high dielectric constant in combination with low dielectric loss, confirming their suitability for capacitor applications. All the composites showed a good optical limiting effect at 532 nm. The third-order nonlinear optical properties of composite films were investigated by Z-scan technique at a wavelength of 532 nm with pulse duration of 7 ns. The conductivity, thermal, dielectric, mechanical and nonlinear optical (NLO) properties were found to increase with f-CNT loading. Thus, the RC–CNT composites have turned out to be excellent next generation materials for energy storage and photonic devices.