JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS Vol. 14, No. 9- 10, September – October 2012, p. 846 - 851 Coloured silica hybrids for functionalizing cellulose materials A. RADITOIU, V. RADITOIU * , V. AMARIUTEI, M. GHIUREA, C.A. NICOLAE, R. GABOR, R.C. FIERASCU, L.E. WAGNER National Research and Development Institute for Chemistry and Petrochemistry – ICECHIM, 202 Splaiul Independentei, 6-th district, 060021, Bucharest, Romania The paper presents new types of coloured organic-inorganic hybrids deposited as coating materials on the surface of cellulose materials by sol-gel processes. Coated materials were characterized by: XRF spectrometry, FT-IR spectrometry, UV-VIS reflectance spectra and colour measurements in CIELAB system, scanning electron microscopy (SEM), thermal analysis (TA) and dynamic mechanical analysis (DMA). Structure-properties relationships of the obtained coated cellulose materials are discussed with respect to the structure and nature of the hybrid organic-inorganic coloured coatings. (Received July 11, 2012; accepted September 20, 2012) Keywords: Silica hybrids, Cellulose materials, Non-ionic dyes, Coatings 1. Introduction In the last years the interest showed for textile fibres has changed with obtaining nanodispersions having a high solid content and particle diameters below 50 nm. Nanosols used as coating materials have the advantage of high storage stability, a good adhesion to textile fibres and require a short drying time at relatively moderate temperatures. Coatings obtained are interesting in particular to functionalize textile surfaces because they can be easily chemical or physical modified allowing changes of the resulting properties in a very extensive domain [1]. There are many studies on the modification of textile fibres using organosilane compounds, many of them focusing on their impact on mechanical properties of the obtained composites. This type of treatments involves condensation of silanole groups with functional groups from the fibre surface. Thermal curing processes, that occur after chemical grafting, leads to a chemical change of textiles surface [2] and as a consequence properties are strongly influenced. Regarding usage of dyes in sol-gel systems on textile substrates, is to be mentioned an enhanced activity for achieving applications of such systems in the biomedical field [3,4], but also in textile dyeing of hydrophilic [5] or hydrophobic [6,7] substrates as: anionic, cationic and non- ionic dyes embedded in various silica networks. Properties of the obtained coatings and the influence of the host matrix on the washing fastness, stiffness, water contact angle, is also subject of several works [8-10]. 2. Experimental 2.1 Materials All of the chemicals used were of laboratory reagent grade and were obtained from Merck (Germany) and Aldrich (USA). Hydrochloric acid (0.1 N), tetraethylortosilicate (TEOS), phenyltriethoxysilane (PhTES), ethanol, tetrahydrofuran (THF) were used in this study as they were received. Silicon anhydride (SiO 2 content: 83.71%) from Merck was used as standard for quantitative XRF measurements. Disperse Red 1 - C.I. 11110 (DR1) was obtained by us as it was described elsewhere [11] and purified by extraction with toluene in a Soxhlet extractor followed by re-crystallization. The preparation of Disperse Red 1 chemically modified with NCOTEOS (DR1-PTES) followed a published procedure [12]. Textile material used was a 100% cotton fabric having a specific weight of 106 g/m 2 , chemically whitened. 2.2 Procedures 2.2.1 Obtaining the impregnation bath A solution made of 3.25 ml TEOS, 3.25 ml PhTES, 3.9 ml solution (DR1 or DR1-PTES 1.7 g / 100 ml THF), 0.65 ml water, 2.35 ml ethanol and a few drops of hydrochloric acid was stirred one hour at room temperature. Reactions were conducted in the usual manner of sol-gel processes [13]. The mixture was maintained under vigorous stirring, at room temperature and used immediately for padding cellulose materials. 2.2.2 Pad-drying procedure A textile test-piece of about 2 g was padded with sol to a degree of assumption of 80%, by several successive passes in a laboratory Ernst BENTZ padding mangle, at a constant rate of 0.5 m/min. and pressure of 0.4 kg/cm 2 . Coated materials were dried at room temperature for 2 h and then subjected to heat treatment at 120 0 C for 1 h in a thermo-fixation oven.