Low molecular weight poly(acrylic acid) with nitrilodi(methylene-phosphonic acid) chain ends for scale inhibition

Poly(acrylic acid) with molecular weight of 5000 was produced by using 2-aminoethanethiol hydrochloride as chain transfer agent. Amine chain end groups of the resulting polyacrylic acid were transformed into nitrilodi(methylenephosphonic acid) by reacting formaldehyde-phosphorous acid in the presence of hydrogen chloride. ¹H NMR, ³¹P NMR and microanalysis were used for structural analysis.The modified polyacrylic acid had much better calcium carbonate scale inhibition effect than commercial poly(acrylic acid).