To understand the intermolecular forces that govern the final characteristics of a material is relevant for the design of new commercial products with tailored optimal properties. This is particularly important in the case of nanocellulose. Nanocellulose (cellulose fibrils of few nanometers in width and up to several micrometers in length) exhibits excellent mechanical properties, including a high Young's modulus, high strength and low density. Due to its unique mechanical properties and renewable nature, nanocellulose is a very promising candidate to replace existing, widely-used, fossil-oil based materials. Of high interest is, for instance, the use of nanocellulose or polymer-nanocellulose composites in the development of tough materials for load-bearing applications (transportation, construction), barrier films for packaging, or biocompatible substrates for medical applications. In the latter case, nanocellulose materials able to withstand high applied loads, with a high resistance to wear and with low friction coefficient could be the basis for a new generation of efficient, low-cost cartilage implants. Although it is assumed that the mechanical performance of nanocellulose materials depends critically on the interphase phenomena between cellulose fibrils and, in the case of polymer-nanocellulose composites, between cellulose fibrils and other polymer molecules, so far that relation is poorly understood. This work is an attempt to unravel such a relation in certain nanocellulose-based, tough biomimetic materials with potential application in transportation or medicine. The colloidal probe microscopy, which combines the high sensitivity of the atomic force microscope and the colloid probe technique, was used to measure the interfacial and friction forces at micro/nanoscale between cellulose microspheres and nanofibrillated cellulose substrates. The lubrication and reduction of adhesion associated to polymer adsorption was also analyzed. The relevance of the results for the design of new nanocellulose materials of interest in the industrial and medical sectors will be discussed.

Relevance of the interfacial and friction forces at micro/nanoscale in the design of nanocellulose materials for transportation or medical applications

247th National Meeting (2014)

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