Self-regenerating, fluorine-free, hydrophobic and oleophobic finishing of textile materials based on self-opening micelles

IGF 20153 N

When using textile materials (e.g. as clothing textiles or textile floor coverings), wetting or penetration of the textile material with liquids as well as contamination of the textile surface is undesirable in a wide range of applications. Textile materials are therefore often finished with fluorocarbon (FC) polymers, which make the textile material water and oil repellent.

Recently fluorochemicals have been strongly criticized because representatives of this group, which are produced as by-products in the production of FC-polymers, are regarded as persistent and bioaccumulative. The environmental and health impacts of fluorochemicals from textile finishes are therefore discussed critically. For first FC polymers (FC8 derivatives), restrictions are already in place.

Against the background of legal regulation of fluorocarbon polymers as well as increasing efforts towards sustainable, environmentally friendly processes, there is a great need in fluorine-free alternatives which allow simultaneous oleophobic and hydrophobic treatment of textiles.

However, there are no alternative processes available yet that allow both hydrophobic and oleophobic treatment of textile materials. So far, only a fluorine-free hydrophobization can be achieved.

A self-regenerating, fluorine-free textile finish was therefore developed within the scope of the research project. With such a textile finish, it is possible to achieve not only water repellency but also repellency against liquids with lower surface tensions, which can penetrate currently available fluorine-free finishes.

The finish consists of micellar aggregates of special copolymers with polydimethylsiloxane (PDMS) side chains (PDMS micelles) statistically distributed in a polymeric matrix.

PDMS micelles open up at the air interface due to polarity inversion at the interface and repulsive interactions in the micelle core, resulting in a monolayer of aligned PDMS side chains on the surface of the textile finishing. Low surface energy combined with high mobility of aligned PDMS chains lead to the good liquid repellent properties of the textile finish.

PDMS micelles present in the matrix do not open due to steric hindrance by surrounding matrix. Mechanical removal of top layer of finishing exposes and opens next layer of PDMS micelles, repeating the process of forming an aligned PDMS chain monolayer (self-regeneration).

The research report is available on request from FRT.

The IGF-project 20153 N of the research association For­schungs­kuratorium Textil e.V., Reinhardtstr. 14-16, D-10177 Berlin, was supported via the AiF within the funding program „Industrielle Gemeinschaftsforschung und -entwicklung (IGF)“ by the Federal Ministry of Economic Affairs and Energy (BMWi) due to a decision of the German Parliament.