NEW POLYURETHANE IONOMERS CONTAINING PHOSPHATE GROUPS

The disodium salt of glycerol 2-phosphoric acid was acidified with cold concentrated hydrochloric acid. The free glycerol 2-phosphoric acid was then extracted with dimethyl sulphoxide and ethanol. The acidic diol, a solid at room temperature with a boiling point of 230-degrees-C, was very hygroscopic. The phosphate diol was incorporated into the polyurethane using methylene di(4-phenyl isocyanate), and polypropylene glycol as the soft segment, by the step growth solution copolymerization in dimethyl sulphoxide at 90-degrees-C in the presence of a catalyst, di-n-butyltin dilaurate. Nuclear magnetic resonance spectroscopy, infra-red spectroscopy, thermogravimetric analysis, stress/strain analysis and the solubility, with different ionic contents of the ionomer, were investigated. The ionic strength of this ionomer is relatively low because the ionic groups are not in the form of salt, but of the acid, and this is reflected in the properties.