On the study of polyurethane ionomer — Part II

AbstractPhotosensitive‐fluorescein polyurethane (PU) ionomer was successfully synthesized at our laboratory. The reaction of toluene diisocyanate with polyester, fluorescein, hydroxypropyl acrylate and other major additives to form the structures of these ionomers has been proven by FT‐IR spectroscopy. For a dilute concentration of photosensitive‐fluorescein PU ionomer molecule in aqueous solution, the fluorescence studied exhibits fluorescence at around 508 nm. In aqueous solution, the number average particle size appears to increase with increasing concentration of epoxy, fluorescein and hydroxypropyl acrylate used to prepare the photosensitive‐fluorescein PU ionomer molecules. The reason for the free volume of photosensitive‐fluorescein PU ionomer molecules is due to strong intermolecular interactions between hydrophilic groups of these ionomer molecules increasing. Therefore, the number average particle sizes of these ionomer molecules increases. Furthermore, the addition of benzoin as a photoinitiator to photosensitive‐fluorescein PU ionomer molecule results in an increase is the average particle size of this ionomer molecule. This is due to increased free volume resulting from strong intermolecular interaction between hydrophilic groups of ionomer molecules. For self‐cured films made by photosensitive‐fluorescein PU ionomer, the tensile strength is seen to increase with increasing concentration of epoxy, fluorescein and hydroxypropyl acrylate, respectively. This may be attributed to increased crosslinking due to strong intermolecular interaction between photosensitive‐fluorescein PU ionomer molecules themselves. However, the addition of benzoin as a photoinitiator to photosensitive‐fluorescein PU ionomers results in an increase in the tensile strength of these ionomers as well. Copyright © 2002 John Wiley & Sons, Ltd.