Molar mass distribution of a commercial aliphatic hyperbranched polyester based on 2,2-bis(methylol)propionic acid.
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.
Zagar
Ema
E
National Institute of Chemistry, PO Box 660, Hajdrihova 19, SI-001 Ljubljana, Slovenia. ema.zagar@ki.si
Zigon
Majda
M
D000081:Acetamides / Q000737:chemistry; D005663:Furans / Q000737:chemistry; D006860:Hydrogen Bonding; D006880:Hydroxy Acids; D008970:Molecular Weight; D011091:Polyesters / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D000081:Acetamides; D005663:Furans; D006880:Hydroxy Acids; D011091:Polyesters; D011422:Propionates; C018674:tetrahydrofuran; C110034:2,2-bis(hydroxymethyl)-propionic acid; C013959:dimethylacetamide