Hyperbranched polyalkoxysiloxanes via AB(3)-type monomers

摘要

We have synthesized polyethoxysiloxanes starting from the AB(3)-type monomers triethoxysilanol and acetoxytriethoxysilane. The polymers are liquid and soluble in organic solvents. Si-29 NMR spectroscopy and MALDI-ToF mass spectrometry analyses show that the polymers have a hyperbranched structure with additional internal cyclization. Si-29 NMR spectroscopy indicates that the polymer synthesized from acetoxytriethoxysilane is less branched than the polymer synthesized from triethoxysilanol. Analysis of the molar mass and mass distribution of the polymers via size exclusion chromatography (calibrated via MALDI-ToF MS and viscosimetry) yields a molar mass of (M) over bar (n)approximate to2 kg.mol(-1) and (M) over bar (w)approximate to8 kg.mol(-1) for polymers synthesized from triethoxysilanol. The molar mass of the polymers synthesized from acetoxytriethoxysilane can be controlled by variation of the polymerization time in the range of (M) over bar (n)approximate to1.8-12 kg.mol(-1) and (M) over bar (w)approximate to2.1-2 200 kg.mol(-1). References: 51