Sol-gel preparation and properties of interpenetrating, encapsulating and blend silica-based urea-formaldehyde hybrid composite materials

摘要

Four different silica-based urea-formaldehyde (UF/SiO2) composite materials were prepared by various sol-gel synthetic procedures to yield an interpenetrating (IPN-UF/SiO2), a micro-size UF resin encapsulated inside silica shell (Encap-UF/SiO2), a micro-size silica encapsulated inside UF shell (Encap-SiO2/UF), and a blend mixture (Blend-UP SiO2) hybrid systems. The thermal properties of the obtained organic-in organic hybrid composite materials were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The structure and morphology of the obtained systems were investigated by infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Their surface porosity and acidity were evaluated from the nitrogen adsorption isotherm and the pH of the corresponding 10% aqueous suspension, respectively. All the results provided evidence for the formation of different hybrid systems with different surface, structural and morphological characteristics. (C) 2004 Elsevier Ltd. All rights reserved.