Multifunctional Nanoparticles for Magnetic Dyeing and Antimicrobial Finishing

Current textile dyes are limited to dyeing purposes only and the dyeing techniques are challenged by growing environmental and economic concerns, i.e., high consumption of water, salts, auxiliaries and energy, and production of substantial amounts of industrial polluting waste waters. We show here that multifunctional nanoparticles were prepared by impregnating the magnetic F₃O₄@SiO₂core-shell structures with both textile dyes and quaternary ammonium moieties. These resulting colored multifunctional nanoparticles not only dyed cotton fabrics but also provided fabrics with potent antimicrobial activities in one step; moreover, they were recycled after the dyeing process using a magnet. In our approach, a textile dye, Disperse Red 1 (DR1) was functionalized with trialkoxysilane groups through the nucleophilic addition reaction of 3-isocyanatopropyl triethoxysilane with DR1. The trialkoxysilane functionalized DR1 and an organosilane quaternary ammonium were used to coat the magnetic F₃O₄ nanoparticle cores through the Stöber method, yielding red multifunctional nanoparticles. These red multifunctional nanoparticles were easily dispersed in water and manipulated with a magnet for their movement. The resulting suspension was used to dye cotton fabrics without the presence of any salts and auxiliaries. Large surface area, high surface energy, and positively charged surface of the multifunctional nanoparticles were believed to be responsible for their high affinity toward the fabrics which ensured high fastness, thus endowing fabrics robust colors and durable, potent antimicrobial properties. Moreover, after the dyeing process, unconsumed dye nanoparticles in the wastewater can be efficiently recycled with a magnet for future use, avoiding tedious wastewater treatment. Thus, this technique provides an environment friendly and cost-effective one-step dyeing and antimicrobial finishing process that will greatly benefit the textile industry, especially for healthcare applications.