Andreas Geissler

This contribution reports an efficient method for the production and use of biocide-loaded cellulose acetate nanoparticles. As well-known model biocides 4-Hexylresorcinol and Triclosan were used for in situ nanoparticle loading during a nanoprecipitation process. We show that the nanoparticle size can be well-controlled by variation of the cellulose acetate concentration during nanoprecipitation. Apart from strong evidence suggesting cellulose acetate particle formation according to a nucleation-aggregation mechanism, we further show that the biocide loading of the particles occurs by a diffusion process and not via co-precipitation. The quantity of particle loading was analyzed by ¹H-NMR spectroscopy of re-dissolved nanoparticles, and it was observed that a decisive factor for high packaging efficiency is the use of a biocide with low water solubility and high hydrophobicity. SEM studies showed no influence on the particle morphology or size by both biocides 4-Hexylresorcinol and Triclosan. Finally, an aqueous nanoparticle dispersion can be coated onto model paper sheets to yield pronounced antimicrobial surface-properties. Nanoparticles loaded with the biocide Triclosan showed a high antimicrobial activity against Bacillus subtilis, a cellulase producing bacteria, if applied to model paper substrates, even at extremely low coating weights of 1–5 g/m², respectively. Additional long-term efficacy renders these nanoparticles ideal for various applications.

This scientific−technical approach describes a unique self‐structuring coating material made of wax and polysaccharide derivatives, which results in extremely water‐repellent properties if applied to solid surfaces. When cooling the coating down from the molten state, the material forms a nanostructured superhydrophobic surface within seconds. This possibility of a fast thermally induced regeneration of nanoscale surface textures creates the potential to restore superhydrophobic coating properties even after mechanical damage caused, among others, by long‐term use and complex processing and machining steps. Therefore, this coating material has great potential for engineering applications such as superhydrophobic wettability of paper surfaces. Depending on a particular application, there are different requirements for the interaction of paper with water. The highest possible water resistance, which is achieved by superhydrophobic properties, is a quality feature for a majority of paper products, such as packaging materials or novel construction materials, since the ingress of moisture is a major cause of paper damage.