Advanced microgel-functionalized polyester textiles adaptive to ambient conditions

Abstract

A new approach toward textile-based multi-functional and stimuli-responsive materials is proposed. Polyelectrolyte microgel technology is combined with conventional functionalization methods of photo- and thermo-crosslinking to activate the surface of polyester textiles, making them interactive with their environment. The microgels consisted of pH/thermo-responsive poly(N-isopropylacrylamide-co-acrylic acid) (PNIAA) microparticles either alone or complexed with oppositely charged macromolecular chains of the pH-responsive natural polysaccharide chitosan. Microgel incorporation into polyester surface layers was achieved either through UV irradiation in the presence of the photoinitiator benzophenone or through low temperature treatment using the natural crosslinker genipin. The adaptivity of the functionalized textiles to ambient conditions of pH, temperature and relative humidity was expressed by changes in the textile physicochemical and water management properties. These changes were found to occur within a physiological pH/temperature range of the human body (pH 4–8 and 20–40°C). More specifically, functionalized polyester textiles exhibited a shift in surface charge from positive to negative values at pH ranging from 5.0 to 6.6, following the trend of the incorporated microgels. Below the microgel Lower Critical Solution Temperature (36oC), the chitosan-containing functionalized textiles exhibited improved water wettability compared with reference textiles. Above 36oC, functionalized textiles had lower moisture regains and higher water vapor transmission rates than the reference textiles. Microgel incorporation was found to be sufficiently durable, in some cases even after 30 washing cycles. However, some of the textile advantageous properties (e.g. whiteness, crease recovery) deteriorated due to the functionalization process. Possible applications of the microgel-functionalized polyester textiles lie in the fields of biomedicine and protective clothing.