D. Jocic

Functionalization of cotton with poly-NiPAAm/chitosan microgel: Part II. Stimuli-responsive liquid management properties

Stimuli-responsive microgel, based on synthetic polymer (poly-NiPAAm) and biopolymer (chitosan), was incorporated onto cotton fabric surface by pad-dry-cure method using 1,2,3,4-butanetetracarboxylic acid (BTCA) as crosslinker. In order to assess the moisture management properties of cotton functionalized with responsive microgel, the effects of temperature, relative humidity and concentration of microgel on water vapour transmission rate (WVTR) and moisture content (MC) were quantified. Since the use of experimental design is considered as a highly attractive feature in dealing with experiments and variables of this nature, the effects were quantified by using a central composite design. The regression equations obtained from the statistical analysis allowed the prediction of WVTR and MC at different ambient conditions. Material properties such as crease recovery and whiteness were also measured. The results indicate that both relative humidity and temperature significantly influence studied responses (WVTR and MC), showing that good perspiration can be achieved at lower humidity levels and at higher temperatures. The observed phenomena are attributed to controlled expansion (or contraction) of the surface incorporated microgel, which acts as a sensor of temperature and as a valve to regulate the water vapour permeability of functionalized cotton.

Functional finishing of aminated polyester using biopolymer-based polyelectrolyte microgels

This study focuses on a microgel-based functionalization method applicable to polyester textiles for improving their hydrophilicity and/or moisture-management properties, eventually enhancing wear comfort. The method proposed aims at achieving pH-/temperature-controlled wettability of polyester within a physiological pH/temperature range. First, primary amine groups are created on polyester surfaces using ethylenediamine; second, biopolymer-based polyelectrolyte microgels are incorporated using the natural cross-linker genipin. The microgels consist of the pH-responsive natural polysaccharide chitosan and pH/thermoresponsive poly(N-isopropylacrylamide-co-acrylic acid) microparticles. Scanning electron microscopy confirmed the microgel presence on polyester surfaces. X-ray photoelectron spectroscopy revealed nitrogen concentration, supporting increased microscopy results. Electrokinetic analysis showed that functionalized polyester surfaces have a zero-charge point at pH 6.5, close to the microgel isoelectric point. Dynamic wetting measurements revealed that functionalized polyester has shorter total water absorption time than the reference. This absorption time is also pH dependent, based on dynamic contact angle and micro-roughness measurements, which indicated microgel swelling at different pH values. Furthermore, at 40 °C functionalized polyester has higher vapor transmission rates than the reference, even at high relative humidity. This was attributed to the microgel thermoresponsiveness, which was confirmed through the almost 50% decrease in microparticle size between 20 and 40 °C, as determined by dynamic light scattering measurements.

Biopolymer-based Stimuli-Responsive Polymeric Systems for Functional Finishing of Textiles

The technological developments of the first decade of 21st century are slowly changing the way we live by controlling our surroundings and regulating our every day life with intelligent objects. Smart Materials and Intelligent Structures are novel disciplines which are currently rapidly growing into an interdisciplinary technology. This new technology is being incorporated in contemporary engineering and design with the aim to create the path for materials to gain “intelligent” features. Textile materials also benefit from the rapid advances in a new interdisciplinary technology. Development of textile materials with new advanced functionalities is the perfect example where these base technologies can be brought together by using the knowledge involving surface science and surface engineering at molecular and atomic level. This knowledge is being responsible for developing and creating a new generation of so-called “smart” textile materials. By redesigning textile material surface, operating at microscopic level, many new possibilities emerge for adapting the macroscopic properties of the material to the present needs of the textile industry and thus fulfil current and future end-user expectations. In this context, this book chapter will focus on an innovative strategy for functional finishing of textile materials by application of surface modifying systems (SMS) based on stimuli-responsive polymers.