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Syntheses of poly[(dimethyl)‐ co ‐(4,7,10,13‐tetraoxatetradecylmethylsilanes)].An evaluation of the use of C 8 K versus Na in the preparation of polysilanes
Author(s) -
Cleij Thomas J.,
Jenneskens Leonardus W.
Publication year - 2000
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20000901)201:14<1742::aid-macp1742>3.0.co;2-h
Subject(s) - polymer chemistry , chemistry , materials science , polymer science
To evaluate the use of C 8 K versus Na as the reducing agent in the preparation of polysilanes, the homopolymers poly(4,7,10,13‐tetraoxatetradecylmethylsilanes) 1 and poly(dimethylsilane) 5 as well as the copolymers poly[(dimethyl)‐ co ‐(4,7,10,13‐tetraoxatetradecylmethylsilanes)] 2 – 4 were synthesized from 4,7,10,13‐tetraoxatetradecylmethyldichlorosilane ( 6 ) and/or dimethyldichlorosilane ( 7 ). C 8 K in comparison to Na gave an increased yield and enhanced purity, when used with polar monomers, such as 6 , that presumably intercalate into graphite. In the presence of increasing amounts of apolar 7 both a decrease in yield as well as purity is observed in the C 8 K based copolymerizations. In contrast, the type of monomer does not affect the results of the Na based copolymerizations. Whereas at ambient temperatures the introduction of dimethylsilane units in 2 – 4 , causes minor changes in the polysilane optical properties, as compared to 1 , at low temperatures differences are discernible both in solution and the solid state (thin film) in the case of 4 Na . Apparently, the incorporated dimethylsilane moieties reduce the mean free energy of defect formation E , i. e. at these low temperatures the silicon backbone adopts a more extended conformation as reflected by the occurrence of an additional “abrupt” transition.