Synthesis of stimuli-responsive ionic cyclopolymers in search of phosphorous-free antiscalants

Ammonium persulfate-initiated cyclopolymerization of maleic acid (HO2CC=CCO2H) (MA) with diallylamine (-NR2, R = CH2 = CH-CH2) derivatives (DADs): R2NH+CH2CO2- (I), R2NCH2CO2-Na+ (II), R2NCH2CO2Et (III), R2NH+(CH2)(3)CO2- (IV), R2N(CH2)(3)CO2Et (V), R2NH+(CH2)(3)SO3- (VI) and R2N(CH2)(3)SO3-Na+ (VII) gave a series of new pH-responsive alternate copolymers: -[(DAD-alt-MA)](n)- VIII-XIV, respectively. Homopolymers XV and XVI of the corresponding monomers IV and V center dot HCl were also synthesized. The evaluation of the synthesized polymers as potential antiscalants in reverse osmosis (RO) plants was examined. An effective scale inhibitor must arrest the formation of scale for a residence time (approximate to 15 min) of feed water in the RO chamber. R2NH+(CH2)(3)CO2- (IV)-alt-MA copolymer XI at a concentration of 5 ppm imparted 99% scale inhibition for 360 min, while at 2.5 and 1 ppm concentrations, the CaSO4 scale inhibitions were found to be 99% and approximate to 100% during 120 and 20 min, respectively, at 40 degrees C. Homopolymers XV and XVI, at a 20-ppm concentration, demonstrated approximate to 95% efficiency in inhibiting mild steel corrosion in 1 M HCl. In some important oilfield applications, requirement of simultaneous scale and corrosion inhibition make these polymers potential candidates for desalination and oilfield applications.

Automated summary

The study showed that a series of new pH-responsive alternate copolymers can be synthesized through cyclopolymerization, some of which exhibit excellent antiscalant properties in reverse osmosis plants, and also demonstrate some corrosion inhibition efficiency in mildly acidic environments.