Syntheses of poly[(dimethyl)-co-(4,7,10,13-tetraoxatetradecylmethylsilanes)]. An evaluation of the use of C8K versus Na in the preparation of polysilanes
Tj. Cleij et Lw. Jenneskens, Syntheses of poly[(dimethyl)-co-(4,7,10,13-tetraoxatetradecylmethylsilanes)]. An evaluation of the use of C8K versus Na in the preparation of polysilanes, MACRO CH P, 201(14), 2000, pp. 1742-1747
Full Paper: To evaluate the use of C8K versus Na as the reducing agent in t
he preparation of polysilanes, the homopolymers poly(4,7,10,13-tetraoxatetr
adecylmethyl-silanes) 1 and poly(dimethylsilane) 5 as well as the copolymer
s poly[(dimethyl)-co-(4,7,10,13-tetraoxatetradecyl-methylsilane)] 2-4 were
synthesized from 4,7,10,13-tetraoxatetradecylmethyldichlorosilane (6) and/o
r dimethyldichlorosilane (7). C8K in comparison to Na gave an increased yie
lds and enhanced purity, when used with polar monomers, such as 6, that per
sumably intercalate not graphite. In the presence of increasing amounts of
apolar 7 both a decrease in yield as well as purity is observed in the C8K
based copolymerizations. In contrast, the type of monomer does not affect t
he results of the Na based copolymerizations. Whereas at ambient temperatur
es the introduction of dimethylsiline units in 2-4, causes minor changes in
the polysilane optical properties, as compared to 1, at low temperatures d
ifferences 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 formulation E, i.e. at these low tem
peratures the silicon backbone adopts a more extended confirmation as refle
cted by the occurrence of an additional "abrupt" transition.