Some thermal studies of polysilanes and polycarbosilanes

Some thermal (TGA and DSC) studies of polysilanes viz., polydimethylsilane (PDMS), copolymer of polydimethyl-methylphenylsilane (PDMMPS), polydimethyl-methylsilane (PDMMS), polydimethyl-methylvinylsilane (PDMMVS) and polycarbosilanes (PCS) synthesized using PDMS have been carried out. PDMS and PDMMPS found more suitable for synthesizing meltable and soluble polycarbosilanes and gave better char yield compared to PDMMVS and PDMMS. The polydimethyl-methylvinylsilane (PDMMVS) did not show any melting behavior and cured at ∼166 °C as an endotherm was noticed in DSC. The PCS-N (mp ∼124 °C) on heating up to 450 °C become non-meltable but remain soluble in common organic solvents, which on further heating up to ∼650 °C become non-meltable and non-soluble. The thermal recycling of the PCS-N at ∼350 °C minimized the exotherms as observed in the DSC. The XRD studies revealed that the α-SiC and β-SiC formation took place at ∼930 and 1250 °C, respectively as reported earlier too.