Synthesis and aqueous solution behavior of water-soluble polyurethane (IPDI-PPG-DMPA) resin

Two types of polyurethane (PU) resins were synthesized by polyaddition of i sophorone diisocyanate (IPDI), poly (propylene glycols: PPG-750 and PPG-200 0), and 2,2-bis(hydroxymethyl)propionic acid (DMPA). Chemical structure of PU was confirmed by H-1 and C-13 NMR analysis. The PU resins were found to be water-dispersible or soluble by neutralization of carboxylic acid groups in DMPA. Aggregate formation behavior of the PU and solubilizing ability f or hydrophobic probe (pyrene) were investigated at 100% neutralization.. Av erage aggregate sizes of the PU resins measured by photon correlation spect roscopy showed large values (ca. 25-120 nm). The aggregate sizes were stron gly affected by the concentration of the resin and total ionic strength in the aqueous phase. The PU resins showed superior solubilizing ability for p yrene in comparison with that of conventional short chain surfactant. Addit ionally, critical micelle concentration (CMC) of the PU resins obtained fro m pyrene fluorescence method showed extremely low values (<10(-3) mol/dm(3) water) and their aggregate numbers were 7.2 and 6.5 for PUR-750 and PUR-20 00, respectively.