Phosphinate oligomers, compositions containing them and methods of making and using them

A predominantly phosphinate containing composition which has as its major ingredient more than 32 mole percent of a phosphinicosuccinic acid oligomer having the probable structural formula: M is H, Na, K, NH4, or mixtures thereof; and m and n are either 0 or a small whole number with the proviso that either m or n is a small whole number and the sum of m plus n is greater than 2. Also disclosed is a method of making these compositions which involves reacting a water-soluble hypophosphite excess maleic acid, in a molar ratio of 2.3 to 3, and the use of these compositions and of the oligomer in the prevention or inhibition of formation of scale in aqueous media, particularly alkaline cooling water.