FORMATION OF ORGANOSILICON COMPOUNDS .116 . THE INFLUENCE OF CHLORINATION, HYDROGENATION, AND CROSS-LINKING ON THE THERMAL-BEHAVIOR OF THE POLYMERIC (-ME2SI-CH2-)(N)

In the reaction of the polymeric (-Me2Si-CH2-)(n) PCS1 with I-2/Cl-2 o nly one methyl group was substituted to form (-CIMeSi-CH2-)(n) PCS2. B y chlorination with I-2/Cl-2/Al2Cl6 we get a further replacement of th e methyl group by chlorine (Si:Cl = 1:1.2; 1:1.18; 1:1.98; 1:2.07). Th e reduction of the chlorination products (Si:Cl=1:1.12 and 1:1.98) wit h LiAlH4 led to SiH-rich derivatives. The thermal behaviour of these d erivatives has been investigated. Up to 800 degrees C the weight loss is 18.5%. Further heating by thermal gravimetry (TG) up to 1400 degree s C results in an additional weight loss of 2% with beta-Sic formation . The polymeric (-ClMeSi-CH2-)(n) PCS2 reacts with MeNH2 to form -MeSi -NHMe groups. Separation of MeNH2 led to a crosslinked chain which the n condenses to a polymer with Si4C10H16N2-units PCSN2. This reaction i s completed at about 300 degrees C, between 500 and 800 degrees C thes e polymer undergos further crosslinking with the elimination of CH4, H -2, and viscous polymers in the destillate. At 800 degrees C in the po lymeric PCSN2 the ratio Si:C decreases from 1:2.5 to 1:1.3, the ratio Si:H from 1:6.6 to 1:2 but the ratio Si:N remains nearly constant at 1 :0.5. The weight loss of the X-ray amorphous sample up to 800 degrees C is 74% however, up to 1400 degrees C no further weight loss is obser ved.