ISSN:
0887-624X
Keywords:
poly(carbosilane)
;
poly(silylenemethylene)
;
glass transition
;
1,3-disilacyclobutane
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Poly(silylenemethylene)s of the types [SiMeRCH2]n and [SiHRCH2]n were prepared by the ring-opening polymerization (ROP) of 1,3-disilacyclobutanes (DSCBs) containing n-alkyl substituents, such as C2H5, n-C3H7, n-C4H9, n-C5H11, and n-C6H13, or a phenyl group on the Si. These new polymers include a monosilicon analog of poly(styrene), [SiHPhCH2]n. Improved synthesis routes to the DSCB monomers were developed which proceed through Grignard ring closure reactions on alkoxy-substituted chlorocarbosilanes. All of these asymmetrically substituted polymers were obtained in high molecular weight form, except for [SiHPhCH2]n. The configurations of all of the polymers were found to be atactic. The aryl-substituted polymers have higher glass transition temperatures (Tgs) and thermal stability than those of the alkyl-substituted poly(silylenemethylene)s. Unlike the polyolefins of the type [C(H)(R)CH2]n, where Tg drops continuously from R = Me to n-Hex, the Tgs of the n-CnH2n+1 (n = 2-6)-substituted [SiMeRCH2]n PSM's appear to reach a maximum (at -61°C) for the R = n-Pr-substituted polymer. Moreover, where it was possible to make direct comparisons among similarly substituted atactic polymers, all of the poly(silylenemethylene)s were found to have lower Tgs than their all-carbon analogs. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3193-3205, 1997
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
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