According to the current state of the art, there are currently no alternatives to the use of fluoropolymers despite intensive research in the field of finishing textiles with fluorine-free coatings for the production of outdoor and sports clothing and especially for protective textiles with high standardised safety standards. The project objective is therefore to develop water-, oil-, dirt- and media-repellent finishes and functionalisations for technical textiles and textiles that are suitable for use as protective and outdoor clothing. For this development, the use of fluoroorganic compounds is completely avoided. The finishes to be developed are also harmless to health and are applied using resource-conserving processes.

The targeted technological development thus forms the basis for textiles that are ecologically and health safe, which on the one hand fulfil the human ecological requirements of the OEKO-TEX^® STANDARD 100 with regard to the parameter PFOA (perfluorooctanoic acids – C8) and on the other hand also take into account the foreseeable tightening amendments to the REACH Regulation – the ban on the use of perfluorinated and polyfluorinated substances. The finishing should be carried out with formulations and technologies that create an optimal balance between product-specific performance and human ecological safety. By avoiding the use of fluorinated substances and substituting them, sustainable products (clothing, protective and home textiles as well as furniture) can be designed through adapted processing. In 2017, around 10,000 tonnes of environmentally harmful perfluorinated or polyfluorinated low molecular weight chemicals (PFCs) were still used annually. The development and the textile industry's commitment to PFC-free use should greatly reduce the use of PFCs and create alternatives.

In the project, exemplary textile, cellulose and PET-based structures are equipped with ultrahydrophobic surface properties, which by definition are characterised by water advancing contact angles qadv > 150° with negligible contact angle hysteresis. Using novel hybrid organosilicon molecules, a combined ultrahydrophobic and oleophobic surface finish is to be achieved while maintaining the synthetic concept.

By developing fluorine-free surface modifiers (production of chemical products), the research project aims at a sustainable finishing of textile structures without limiting their functional properties. Fluorine-free ultra-hydrophobic, oil-repellent, dirt-repellent textile finishes are to be synthesised, applied and functionally tested according to a novel concept.

The following approach is envisaged:

1. Adsorptive binding of water-soluble polymers, such as polyamines, as reactive anchors for post-functionalisation reactions to the textile structure without chemical reaction of the adhesion-promoting layer with surface groups (e.g. hydroxyl groups of cellulose-based cotton).
    
2. Irreversible adsorptive binding to the textile fibres through partial post-crosslinking with bi- or multifunctional reagents within the adsorption layer
    
3. Covalent coupling of tris-(trimethylsiloxy)silyl compounds (TRIS), which contain a functional group in the position that is reactive towards amino groups. In the position of the molecule are sterically demanding groups that lead to hydrophobic surface properties
    
4. By varying the graft density of the TRIS, the wetting behaviour of the textile substrates towards contacting water is controlled. Alternatively, co-polymers of methacrylic acid esters can be produced as covalently coupling coatings. In addition to methyl methacylate units, these also contain sequences with glycidyl methacrylate as a reactive component for the polyamines and 3-[tris(trimethylsiloxy)silyl]propyl methacrylate as a hydrophobicising component.
    
5. In order to achieve the oleophobic, dirt-repellent surface properties, the steric demand in the position of the TRIS is increased from methyl to isobutyl to trimethylsilyl residues. In this process, the fibre surface is shielded by outwardly aligning head groups and the outermost groups (short alkyl radicals) prevent solvation by oils. If successful, a fluorine-free substance class would be created that enables both hydrophobic and oleophobic and soil-repellent surface modification.
    
6. For ultrahydrophobic or oleophobic surface finish, a sufficient roughness with a certain aspect ratio of the surfaces to be finished is also required, which is synergistically composed of a micro- and a nanoscale roughness. Even if textile surfaces naturally have a roughness, they do not a priori have to meet the requirements for achieving ultrahydrophobic or oleophobic properties. For this reason, the synthetic concept described above allows the covalent integration of silicate nanoparticles and/or microparticles into the functionalisation layer, if required, for the targeted adjustment of the roughness.

In the course of the project, findings on the development of effective water-, oil-, dirt- and media-repellent finishes meeting requirements are to be developed and their applicability to technical textiles and textiles used as protective and outdoor clothing is to be demonstrated in terms of their effectiveness. In the project, the functionalisations and the application on textiles are to be optimised. This will provide complementary research and basic development work for SMEs in the fields of textiles, finishes as well as application processes, which do not have sufficient personnel and financial capacities. The international competitiveness of these SMEs is thus increased.

The potential user group consists of textile companies, companies in the chemical industry, mechanical and plant engineering, manufacturers and users of equipment. The development of fluorine-free consumer goods and articles of daily use meets the increased and growing awareness of a healthy and sustainable lifestyle, which is es-sentially linked to living in an intact environment.

The project focuses on the development of new PFC-free finishing agents that can be used for contract furniture, outdoor textiles (e.g. outdoor furniture, sun sails) and functional textiles (sportswear) as well as protective clothing. The developments are aimed, among others, at small and medium-sized enterprises in the field of technical textiles), in particular HOMETECH , SPORTTECH, PROTECH and CLOTHTECH. These companies are given the opportunity to expand their business with the use of functionally appropriate finishes or optimised functionalisation technologies using their core competences. Innovative material developments are of great importance for the German textile industry in order to consolidate or establish this technological lead on the European and international market.