Interactions between aminated cellulose nanocrystals and quartz: Adsorption and wettability studies

• Adsorption of CNCs on quartz.
• Hypothesis of different orientations of CNCs on the quartz surface.
• Comparison of the specific surface free energies of rough and smooth quartz surfaces coated with CNCs.

Cellulose nanocrystals (CNCs) are potential high-performance, biodegradable, and environmentally-friendly alternatives to the oil-derived chemicals currently used in mineral processing. For this purpose, the understanding of phenomena associated with interactions between CNCs and minerals is crucial. In the present study, aminated CNCs with varying crystal sizes and crystal size distributions were examined in terms of their adsorption properties on quartz and the wetting properties of quartz surfaces after CNC adsorption. CNCs with varying alkyl chain lengths were obtained from consequent periodate oxidation and reductive amination, followed by mechanical high-intensity homogenisation. The adsorption of CNCs was studied based on polyelectrolyte titration. An enhanced interaction between CNCs and the quartz surface, including decreasing CNC surface charges, was obtained. Subsequently, wetting studies of CNC-coated quartz were performed using the sessile drop method. The specific surface free energies of both the rough and smooth surfaces were obtained and compared to determine the effects of roughness on wetting properties. The results showed that smooth surfaces possess a low specific surface free energy due to the absence of surface heterogeneities. For rough surfaces, the specific surface free energy was decreased as the extended alkyl chains of adsorbed CNCs modified the wetting properties of the surface.

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