Wettability and surface composition of partly and fully regenerated cellulose thin films from trimethylsilyl cellulose

The wettability and surface free energy (SFE) of partly and fully regenerated cellulose model surfaces from spin coated trimethylsilyl cellulose were determined by static contact angle (SCA) measurements. In order to gain detailed insight into the desilylation reaction of the surfaces the results from SCA measurements were compared with data from other surface analytical methods, namely thickness measurements, X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared spectroscopy (ATR-IR). Additionally, the influence of ultra high vacuum treatment (UHV) during XPS measurements on the water wettability and surface morphology of regenerated cellulose thin films was investigated. The wetting of polar and non-polar liquids increased with prolonged regeneration time, which is reflected in the higher SFE values and polarities of the films. After UHV treatment the water SCA of partly regenerated films decreases, whereas fully regenerated cellulose shows a higher water SCA. Therefore it is assumed that volatile desilylation products tend to adsorb on partly regenerated films, which strongly influences their wettability.

Wettabilities (left) and surface morphology (right) of cellulose model films, regenerated from trimethylsilyl cellulose for different regeneration times, were investigated and compared with the elemental composition of these films.Figure optionsDownload high-quality image (80 K)Download as PowerPoint slideHighlights
► We investigate the wettability and surface free energy of regenerated cellulose films.
► The surface elemental composition is compared with the wetting behavior.
► Nanometric morphological changes of vacuum treated model films are observed.
► The adsorption of regeneration products on the model films influences the wettability.