Perstorp Holding 1H 2008: Research co-operation in bio-chemical processes

Abstract

The determination of absolute molar mass averages (MMA) and molar mass distribution (MMD) of the fourth generation hyperbranched polyester Boltorn H40 (Perstorp Specialty Chemicals AB), synthesized from 2,2-bis(methylol)propionic acid (bis-MPA) as the AB2 monomer and ethoxylated pentaerythritol as the B4 core molecule was studied in dependence on the type of solvent, preparation procedure and solution concentration. Due to a large number of polar hydroxyl groups, ester, and also some residual carboxyl groups, a very stable H-bond network is formed at room temperature, that can-not be completely disrupted by dissolving the sample in solvents such as tetrahydrofuran (THF), N,N-dimethylacetamide (DMAc), a mixture of THF and methanol (9:1, v/v), and a solution of 0.7% LiBr in DMAc. The H-bonds between the polar groups break down completely and the dissolution of Boltorn H40 on the molecular level is achieved only when the sample is thermally pretreated at a minimum 140 °C for at least 20 min prior to dissolution in solvents THF/methanol or LiBr/DMAc. Thus, determined MMA and molar mass distribution (MMD) of Boltorn H40 are independent on the kind of the solvent and solution concentration.