Title Etherification as side reaction in the hyperbranched polycondensation of 2,2-bis(hydroxymethyl)propionic acid
Date 17.04.2002
Number 10133
Abstract The existence of ether byproducts could be clearly proven for the hyperbranched polymerization of 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) using NMR spectroscopy. Polymerizationexperiments were performed under standard conditions with different catalysts. The ether structureswere identified by characteristic <SUP>13</SUP>C NMR signals of the quarternary carbons and of the ether methylenecarbons. Different substitution pattern of these ether units could be distinguished. Using high-resolutionmagic-angle spinning (HR-MAS) NMR spectroscopy also cross-linked, swollen samples could be analyzed.The amount of ether side products was calculated from <SUP>1</SUP>H NMR spectra after alkaline hydrolysis of thepolymer samples. Etherification can occur as an intramolecular reaction resulting in cycles. Intermolecularetherification results in molecules with two or more focal groups which can act as cross-linker in thepolymerization. Thus, cross-linked samples were obtained at high degrees of conversion.
Publisher Macromolecules
Citation Macromolecules 35 (2002) 3514-3519
Authors Komber, H. ; Ziemer, A. ; Voit, B.
Tags aliphatic polyesters structural units polymers polymerization cyclization dendrimers monomers kinetics nmr

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