Original scientific paper
Softening of Octyl-modified Phenylsilsesquioxanes
Jelena MACAN
orcid.org/0000-0003-0614-194X
; University of Zagreb, Faculty of Chemical Engineering and Technology, Zagreb
Kiyoharu TADANAGA
; Osaka Prefecture University, Graduate School of Engineering, Department of Applied Chemistry, Osaka, Japan
Masahiro TATSUMISAGO
; Osaka Prefecture University, Graduate School of Engineering, Department of Applied Chemistry, Osaka, Japan
Abstract
Octyl-modifi ed phenylsilsesquioxanes were prepared from phenyltriethoxysilane and octyltriethoxysilane by two-step acid-base catalysed sol-gel process. Resulting silsesquioxanes were characterized by scanning electron microscopy, X-ray diffraction analysis, gel permeation chromatography and Fourier-transform infrared spectroscopy, while the thermal properties were investigated by differential scanning calorimetry and thermogravimetric analysis. Morphology of polysilsesquioxanes was found to greatly depend on ratio of alkoxides, presumably because of poor miscibility of long alkyl chains which results in a less homogeneous initial mixture. Long alkyl chains also present steric hindrance to condensation of phenyltriethoxysilane eventually preventing the formation of particles. Incomplete condensation caused the decrease of softening temperature from 160°C to ~50°C and overall poorer thermal stability of polysilsesquioxanes. Decrease in initial temperature of degradation by at least 150°C is probably caused by alkyl chains exposed on the surface of the particles. Increased solvent content improves incorporation of octyl chains due to better solubility and yields polysilsesquioxanes with a more regular structure and a more homogeneous particle size distribution. On the other hand it adversely infl uences the level of condensation and the softening temperature.
Keywords
organic-inorganic hybrid material; polysilsesquioxanes; sol-gel process; thermal properties
Hrčak ID:
78490
URI
Publication date:
16.3.2012.
Visits: 1.214 *