The development of a novel smart material based on colloidal microgels and cotton

Colloidal microgels are often described as "smart" due to their ability to undergo quite dramatic conformational changes in response to a change in their environmental conditions (e.g. temperature, pH). A range of novel smart materials were developed by the incorporation of colloidal microgels into cotton fabric. A series of microgels have been prepared by a surfactant free emulsion polymerization based on N-isopropylacrylamide (NIPAM) monomer. Poly(NIPAM) is a thermosensitive polymer which undergoes a conformational transition close to the human skin temperature. Poly(NIPAM) was co-polymerized acrylic acid (AA), to prepare pH/temperature-sensitive microgels. Microgel particles were characterized by scanning electron microscopy (SEM), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, and dynamic light scattering (DLS). This research aims at coupling microgel particles onto cotton fibers and comparing between different attachment techniques. The coupling reactions between microgels and cotton cellulose are only feasible if they both have appropriate functionalities. For microgels, this was achieved by using different initiators which introduce different functional groups on the particle surface and different surface charges. Cotton samples were successfully modified by carboxymethylation, periodate oxidation, grafting of 1,2,3,4-butanetetracarboxylic acid, and chloroacetylation in order to target possible reactions with the terminal functional groups of the microgel particles. Microgels were attached to the cotton fabrics using different methods and the bonds formed were determined by ATR-FTIR spectroscopy and SEM. The reaction yields were quantified gravimetrically and the maximum weight increase of cotton samples due to the attached microgels was around 24% (w/w).