Smooth and flexible filler-nanocellulose composite structure for printed electronics applications

A new type of micro/nanocomposite was made by using only micro fibrillated cellulose and inorganic fillers. This composite structure can contain up to 90% fillers being still mechanically stable and flexible. Calendering can be used to produce dense structures with extremely smooth surface. To study the effect of filler shape and type, both kaolin and precipitated calcium carbonate (PCC) based sheets were examined. Microscopy (cross-sectional and surface SEM images) and mechanical and morphological properties, including strength properties, surface roughness and dimensional stability as a function of moisture were analysed. After calendering the surface of the PCC containing sheets was smoother than that of photopaper and in the same level as reference plastic film Mylar A. The dimensional stability of the sheets was clearly better than that of paper sheets. The combination of a good dimensional stability with low surface roughness makes these structures potential for printed electronics applications, in which they could replace oil-based plastic substrates. Suitability for printed electronic applications was tested by inkjet printing conductors with silver nanoparticle ink. The sheet resistances of conductors printed on kaolin based sheets were close to those printed on plastic Mylar A film.