Spin coated cellulose nanocrystal/silver nanoparticle films

In this study, thin films of cellulose nanocrystals (CNC) and silver nanoparticles (Ag) were assembled on different substrates by spin coating. The effect of substrates, deposition parameters, and nanocrystal modification on the topographical and hydrophilic properties of the obtained layers was investigated. Dilute concentrations of pristine cellulose nanocrystals (CNC) and surfactant modified crystals (s-CNC) were used in order to evaluate the effect of modification and concentration on the uniformity of the spin coated cellulose/silver layers. Morphological investigations by field emission scanning electron microscopy and atomic force microscopy were performed in order to prove the uniformity of the obtained films, while the wettability of different surfaces were studied and correlated to the cellulose modification and content. The ability of s-CNC to form a stable dispersion in chloroform permits the formation of a uniform cellulose film on the substrate surfaces generating regular films during the spin coating process. Topographical investigations show, on the other hand, that the CNC/Ag suspension produces a non-uniform distribution. These effects can be mainly attributed to the surfactant action rather than to the chemical and electrical properties of the substrate surface. Finally, contact angle studies, underline the hydrophilic nature of s-CNC/Ag based films highlighting that the wettability properties are strongly influenced by the cellulose nanocrystal nature.