Featuring exfoliated 2D stacks into fractal-like patterns in WS2/carboxy methyl cellulose nanocomposites

We report on the formation of fractal-like structures with 2D layer support derived from exfoliated WS2 stacks in cellulose environment (NaCMC, sodium carboxymethyl cellulose). Morphological features and surface topography are studied on 1–4 wt.% WS2/NaCMC nanocomposite films by employing high resolution scanning electron microscopy (HR-SEM) and atomic force microscopy (AFM) employed in semi-contact mode. The development of termite-like, fractal patterns in the nanocomposites can be visualized from the micrographs. Using a box-count method, we predict bi- and tri-modal fractals in the background of 2D, giving out asymmetric shapes in the dimension vs. frequency curves. While typical fractal dimension reduces from 1.98 to 1.6 with increasing WS2 content, the AFM images exhibited an evenly spread rough units while giving a root mean square (RMS) roughness of σ = 66.5 nm, for 4 wt.% specimen. Moreover, Raman analysis exhibited an augmented in-plane (E12g ∼350 cm−1) to out-of-plane (A1g ∼418 cm−1) intensity ratio with an increase in WS2 loading. Also, the intensities of individual Raman modes were found to vary nonlinearly with an increase in concentration of WS2(1-16%) being dispersed in cellulose-based polymer. Furthermore, the force constants are estimated using vibrational frequencies observed in the fourier transform infrared (FTIR) spectra which predict several orders of higher strength in W−S relative to S−S, depending on stretching or bending vibrations. The hexagonal, 2H phase of WS2 system with prominent (002) diffraction plane along the c-axis representing crystalline nature in the composites can be seen from the XRD patterns. Association of fractal-like textural patterns in 2D is expected to draw implications in advanced sensing, antifouling, photo-catalysis, energy storage etc.