Multifunctional coatings for plant-based textiles and other cellulosic substrates

Many materials and surface treatments used today are based on unsustainable fossil-fuel derived synthetic polymers. Cellulose, a raw material from nature, has the potential to be used in many applications, but its widespread application is hampered by its inherent hydrophilic properties. In this work, wax particles are used together with polycations to render cellulosic surfaces hydrophobic yet breathable using the layer-by-layer method. Already two bilayers gave good hydrophobicity, which could be enhanced by optimizing the polycation adsorption, the curing temperature and surface roughness of the substrate. The adsorption and layer properties were studied by quartz crystal microbalance with dissipation and atomic force microscopy, the effect of curing temperature was evaluated by scanning electron microscopy, water contact angle and X-ray photoelectron spectroscopy, and the surface roughness was studied by white light interferometer. The coatings were studied on thin films, free-standing cellulose nanofibril films, textiles and all-cellulosic composites. Large-scale fabrics could also be coated. Cooling properties could be added by functional pigments, and dehydroabietanes were studied as contact-active, biocompatibile antimicrobial agents. The results showed that only a small amount of the dehydroabietanes needed to be on the surface to introduce good antimicrobial properties, and the hydrophobicity was increased at the same time. The various surface modifications could enhance the properties of cellulosic materials consequently increasing the use of natural and non-toxic materials in various applications.