Spectroscopic Analysis of Binary Mixed-Solvent-Polyimide Precursor Systems with the Preferential Solvation Model for Determining Solute-Centric Kamlet-Taft Solvatochromic Parameters.
Hydrogen bond donor/acceptor mixed-solvent systems for solutes that exhibit strong specific interactions are not readily characterized with methods that depend on solvatochromic parameters. In this work, the reaction of two monomers, 4,4′-oxidianiline (ODA) and pyromellitic dianhydride (PMDA), to form the common engineering plastic precursor, poly(amic acid) (PAA), are studied for the tetrahydrofuran (THF) mixed-solvent systems (THF-methanol, THF-ethanol, THF-water) with spectroscopy. Solute-centric (SC) Kamlet–Taft solvatochromic (K-T) parameters for the solvent environment around the monomer are determined using a proposed model that incorporates spectroscopically determined local composition (X(L)) around the ODA monomer and the preferential solvation model. For the example reaction to occur under homogeneous conditions, mixed-solvent conditions need have HBA-rich local compositions (0.30 < X(HBA)(L) < 0.83), high solute-centric basicity (β(SC) > 0.60), high solute-centric polarity, (π(SC)* > 0.63), and low solute-centric acidity (α(SC) < 0.63). The method developed allows characterization of mixed-solvent effects and can be readily extended to other systems that have strong specific interactions.
Graduate School of Engineering and ‡Graduate School of Environmental Studies, Research Center of Supercritical Fluid Technology, Tohoku University , Aramaki Aza Aoba 6-6-11, Aoba-ku, Sendai 980-8579, Japan.
Alif
A
Duereh
Graduate School of Engineering and ‡Graduate School of Environmental Studies, Research Center of Supercritical Fluid Technology, Tohoku University , Aramaki Aza Aoba 6-6-11, Aoba-ku, Sendai 980-8579, Japan.
Yoshiyuki
Y
Sato
Graduate School of Engineering and ‡Graduate School of Environmental Studies, Research Center of Supercritical Fluid Technology, Tohoku University , Aramaki Aza Aoba 6-6-11, Aoba-ku, Sendai 980-8579, Japan.
Richard Lee
RL
Smith
Graduate School of Engineering and ‡Graduate School of Environmental Studies, Research Center of Supercritical Fluid Technology, Tohoku University , Aramaki Aza Aoba 6-6-11, Aoba-ku, Sendai 980-8579, Japan.
Hiroshi
H
Inomata
D007094:Imides / Q000737:chemistry*; D008956:Models, Chemical; D012997:Solvents / Q000737:chemistry*
D007094:Imides; D012997:Solvents