화학공학소재연구정보센터
Polymer, Vol.48, No.7, 1884-1892, 2007
NMR and MALDI-TOF MS study of side reactions in hyperbranched polyesters based on 2,2-bis(hydroxymethyl)propanoic acid
Hyperbranched polyesters of 2,2-bis(hydroxymethyl)propanoic acid (BMPA) with various molar ratios of tetra(hydroxymethyl)methane (PE) core molecule were characterized by NMR spectroscopy and MALDI-TOF mass spectrometry. In all polyesters, the formation of ether groups was observed. The extent of etherification increased with increasing PE content. This was assigned to a higher reactivity of PE towards etherification than BMPA. Intra- and intermolecular etherifications and intramolecular esterifications were detected by MALDI-TOF MS on the core molecule-containing polyesters, resulting in the formation of cycle-containing hyperbranched molecules. The ratio of cycle-containing molecules reached 50% at high reaction time for the polyester without core molecule, but was much lower for the polyesters containing a core molecule. As a consequence of these side reactions, the control of hyperbranched polyester molar mass by varying the core molecule (chain limiter) molar ratio is much more difficult than for linear polyesters. (c) 2007 Elsevier Ltd. All rights reserved.