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The article presents a study which synthesized and characterized poly(urethanes) by solution polymerization from bis(chloroformates) and aromatic diamines with both silicon (Si) or germanium (Ge) as central atom. Poly(urethanes) with Ge showed higher thermal stability than the corresponding Si because of the higher bond energy of the carbon (C)-Ge bond in front of the C-Si one. Poly(urethanes) with aromatic side rings indicated higher thermal stability than those with methyl groups.

Following the reaction route between a diphenol and phosgene/toluene solution in basic medium, six new bis(chloroformates) containing germarylene or silarylene units were synthesized with good yield. The variation on the structure is due to the nature of the groups bonded to the heteroatom. Therefore, combinations of Me, Et and Ph groups were used. 4,4′-(Diethylsilylene)bis(phenyl chloroformate), 4,4′-(ethylmethylsilylene)bis(phenyl chloroformate) and 4,4′-(diethylgermylene)bis(phenyl chloroformate) were obtained as a slightly yellow oil, while 4,4′-(diphenylsilylene)bis(phenyl chloroformate), 4,4′-(methylphenylsilylene)bis(phenyl chloroformate) and 4,4′-(diphenylgermylene)bis(phenyl chloroformate) were obtained as a white solid. The new bi-functional monomers were characterized by FT-IR, 29Si-, 13C- and 1H-NMR spectroscopy and elemental analysis. The Tm of the products in general was higher in samples containing germanium as the central atom, compared to those containing silicon. [ABSTRACT FROM AUTHOR]

The thermal properties of poly(carbonates) and poly(thiocarbonates) containing silicon or germanium in the main chan, derived from thediphenolsbis(4-hydroxy-phenyl)-dimethylsilane, bis(4-hydroxyphenyl)-dimethylgermane, bis(4-hydroxy-phenyl)-diphenylsilane and bis(4-hydroxyphenyl)-diphenylgermane, and phosgene or thiophosgene, were studied by differential scanning calorimetry and dynamic thermogravimetry. Polymers containing phenyl groups bonded to the heteroatoms showed higher Tg values, and the same was valid for those with Ge in respect to Si. Poly(carbonates) showed higher Tg values than poly(thiocarbonates). The thermogravimetric curves revealed that poly(carbonates) are more stable than poly(thiocarbonates)and the same is valid for those containing Ge with respect to the silicon-containing polymers. The kinetic parameters associated with the degradation process, showed that probably there are complex degradation mechanisms, which depend on the heteroatom in the main chain, Si or Ge, and the groups bonded to it, and the nature of the functional group, carbonate or thiocarbonate. [ABSTRACT FROM AUTHOR]