Thermally induced phenomena leading to degradation of poly(silsesquioxane) materials

Thermal degradation of oligomeric ladder-like vinyl- and phenylsilsesquioxanes can proceed at relatively low temperatures via evaporation of the shortest oligomers, accompanied by partial redistribution of side groups. The results of thermogravimetric (TGA) and differential thermogravimetric analysis (DTG) as well as differential scanning calorimetry (DSC) of the thermal decomposition process were combined with studies on the structure of the formed volatiles using Fourier transform infrared spectroscopy (FTIR) and gas chromatography coupled with mass spectrometry (GC–MS), as well as FTIR examination of the solid residues. The investigations have shown that the evaporation of oligomers is the main but not the only reason for the matrix decay. It can be accompanied by partial crosslinking of organic substituents even at relatively low temperatures. The latter process becomes more significant on both prolonged exposure to the mild heating or at temperatures higher than those characteristic for evaporation of oligomers.