Preparation and characterization of new polycarbosilanes : part 1, synthesis, characterization and thermal properties of substituted poly(silylenemethylenes); part 2, stoichiometric polycarbosilane precursors to SiC
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Authors
Shen, Qionghua
Issue Date
1995-12
Type
Electronic thesis
Thesis
Thesis
Language
ENG
Keywords
Polymer chemistry
Alternative Title
Abstract
1,1 ,3,3-tetraalkyl-1 ,3-disilacyclobutanes were prepared from the reaction of 1,1,3,3-tetrachloro-1,3-disilacyclobutane (TCDSCB) with various RMgX reagents. ROP of these monomers gave the symmetrically substituted polymers, [SiR2CH2]n in which R ranges from ethyl to n-hexyl groups. In comparison with the asymmetrically substituted polymers [SiMe(R)CH2]n, the molecular weight of the [SiR2CH2]n polymers decreased with the increase of the
length of the alkyl groups, owing, presumably, to the steric hindrance from the alkyl groups during the ROP. DSC analysis showed that two endothermic transitions were found in all of the dialkyl substituted polymers [SiR2CH2]n, but the intermediate phases in these polymers existed in a very narrow temperature range in comparison with those phases in the corresponding poly(siloxanes) [SiR20]n and poly(silanes) [SiR2O]n. Lower thermal stabilities were observed for the [SiR2CH2]n polymers substituted with the longer side chains. All of the [SiR2CH2]n polymers gave low ceramic yields due to the lack of cross-linking groups.
Description
December 1995
School of
School of
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY