Investigation of Plasma-Assisted Functionalization of Graphitic Materials for Epoxy Composites

Innovative surface bio-functionalization by fungal hydrophobins and their engineered variants

Research on innovative surface functionalization strategies to develop materials with high added value is particularly challenging since this process is a crucial step in a wide range of fields (i.e., biomedical, biosensing, and food packaging). Up to now, the main applied derivatization methods require hazardous and poorly biocompatible reagents, harsh conditions of temperature and pressure, and are time consuming and cost effective. The discovery of biomolecules able to adhere by non-covalent bonds on several surfaces paves the way for their employment as a replacement of chemical processes. A simple, fast, and environment-friendly method of achieving modification of chemically inert surfaces is offered by hydrophobins, small amphiphilic proteins produced by filamentous fungi. Due to their structural characteristics, they form stable protein layers at interfaces, serving as anchoring points that can strongly bind molecules of interest. In addition, genetic engineering techniques allow the production of hydrophobins fused to a wide spectrum of relevant proteins, providing further benefits in term of time and ease of the process. In fact, it is possible to bio-functionalize materials by simply dip-casting, or by direct deposition, rendering them exploitable, for example, in the development of biomedical and biosensing platforms.

Investigation and Optimization of Vacuum Plasma Treatment of PA66 Fabric for Reduced Fire Retardant Consumption

Flame retardant (FR) textiles were obtained by surface treatments of polyamide 66 fabrics with microwave (MW) plasma technology in order to reduce the amount of FR involved in the fabric finishing process. More specifically, MW vacuum plasma was employed for polymer surface activation by using a helium/oxygen (He/O₂) gas mixture, evaluating the effect of different treatment parameters on the affinity toward thiourea impregnation. Surface fabric modification was investigated both in terms of uniformity and increased thiourea absorption by infrared spectroscopy, wicking properties, and gravimetric characterization to define an operative window for plasma treatment conditions. According to the results obtained, the dry add-on content of thiourea improved up to 38%, thanks to the increase of the fabric surface activation. The effectiveness of plasma treatment resulted in an absolute increase up to 2% in limiting oxygen index (LOI) performance with respect to untreated fabric. As a consequence, a drastic reduction of 50% in thiourea concentration was required to achieve a similar fire retardant performance for plasma-treated fabric. On the basis of these preliminary results, a design of experiment (DoE) methodology was applied to the selected parameters to build a suitable response surface, experimentally validated, and to identify optimized treatment conditions. At the end, a final LOI index up to 43% has been reached.