Estruturação com partículas de sílica e silanização binária no desenvolvimento de revestimento para tecido de algodão

Abstract

The improvement on the properties of cotton fabrics to make them hydrophobic and durable, has been carried out mainly through the addition of fluorinated compounds, which implies on the formation of substances harmful to humans and the environment. Thus, this work proposed the functionalization of cotton by electrostatic deposition of core-shell fluorescent silica particles (SiPs) with two different sizes (150 nm and 600 nm) and surface charges (positive and negative), and binary silanization, using a mixture of two hydrophobic organosilanes. The particles were characterized in terms of size distribution, polydispersity index (PDI), and zeta potential (ζ). The dynamic light scattering (DLS) technique was used to determine the hydrodynamic diameter (HD) and PDI, and electrophoretic mobility to obtain ζ. Different treatments applied to the fabric were systematically evaluated, considering three parameters: particles’ coating, covalent bond with silanes, and curing process. The produced SiPs were considered monodisperse and stable in aqueous media. To assess hydrophobicity and durability, the material was analyzed for its wettability by measuring the water contact angle (WCA), repellency grade (GR), and water uptake (CA). Laser scanning confocal microscopy (LSCM) analysis verified the distribution of the silica particles along the cotton fibers and proved their fluorescent nature. Images obtained by scanning electron microscopy (SEM) enabled to assess the state of the fibers and the presence of the nanostructures. Particle impregnation and electrostatic assembly were not enough to guarantee lasting hydrophobicity. However, the functionalization with hydrophobic organosilanes and the electrostatic deposition of SiPs provided an effective and long-lasting coating (10 washes), maintaining the WCA above 130º, GR of 3 and lower CA (165%) compared to pure (600%) and silanized cotton (340%). The presence of SiPs helped to retain the silanization layer and, in a complementary way, this layer increased the adhesion of particles in the textile. Thus, a superior performance was observed when the fabric surface was treated with silica particles and a binary mixture of silanes. In this sense, the methodology developed in this study consists of an effective ecologically sustainable alternative in comparison to the conventionally used functionalization processes.