Reaction pathways during the thermal conversion of polysiloxane precursors into oxycarbide ceramics

Study on the synthesis and thermal degradation of silicone resin containing silphenylene units

“…It is considered that water comes from the condensation of the residual Si-OH groups. As previously reported [9,18,19], Si-OH groups still existed in cured silicone resins. In this study, silphenylenes units in the silicone resin increased the rigidity of the backbones and decreased the mobility of Si-OH groups, so a few Si-OH groups still existed in the cured silicone resin even though the curing temperature is up to 270 • C. The mobility of backbone would increase with the increase of temperature, so the mobility of residual Si-OH groups would increase and react again when temperature was high enough.…”

“…Additionally, the appearance of peak at around 1360 cm −1 indicates the formation of Si-CH 2 -Si structure [25]. As previously reported [18,19,24], the formation of Si-CH 2 -Si structure is a radical reaction through the cleavage of Si-C and C-H bonds. This reaction results in crosslinking of the residue and finally formation of silicon-oxycarbide.…”

Branched Polyesters From Germylated and Fatty Compounds

“…The higher molecular weight polymers give rise to higher pyrolysis residues. This behavior is consistent with that also observed for similar preceramic polymer systems, such as polysicarbosilanes and polycarbosizanes 37 . The transesterification reaction of germylated fatty tri-ester to obtain 1, 2 and 3 involved the use of three different diol monomers; 1,4-butandiol, PTMO 650 and PTMO 1000 represented by the following general structure:…”

“…It is well known that aromatic rings produce a residual free carbon at elevated temperatures much more effectively than linear hydrocarbon chains 37 . Also, the presence of aromatic rings in the precursors enhances processing properties.…”

High temperature structure evolution of macroporous SiOC ceramics prepared by a sol–gel method

“…SiOC is a metastable phase in which the silicon atoms are bonded to oxygen and carbon atoms simultaneously [1]. It often appears to be amorphous by X-ray diffraction but has a heterogeneous structure at nanometer-sized scale [2][3][4][5][6][7][8].…”