Acrylic acid - 2 acrylamido-2-methylpropane sulfonate - hydroxypropyl acrylate synthesis by RAFT polymerization with potential application as antiscalant in water treatment systems

The AA-AMPS-HPA terpolymer (acrylic acid—2-acrylamido-2-methylpropane sulfonate—hydroxypropyl acrylate) synthesis was carried out by means of a controlled one-step RAFT polymerization mechanism. The material was synthesized based on monomers with different functional groups considered environmentally friendly as they do not contain phosphorus in their structure. Optimal synthesis conditions were established, covering the following parameters: monomer concentration in the solution, RAFT agent and initiator concentration, temperature and reaction time. The characterization of the AA-AMPS-HPA copolymer included physicochemical analysis, structural analysis (FTIR, ¹H and ¹³C NMR) and evaluation of thermal properties (TGA and DSC). The rate of polymerization and monomer composition were calculated using NMR techniques. In the obtained polymer, the carboxylic groups compose the main chain, and these are complemented with sulfonates, amides, ester and hydroxyl groups which allow interacting with ions in the solution, precipitated salt molecules to halt and slow down the grow of inorganic salts. The terpolymer is stable around 100 ºC which is the maximum conditions expected for its use as an antiscalant agent. The terpolymer obtained showed a complete inhibition of calcium sulfate and calcium phosphate with 5 ppm and 30 ppm dosage respectively; in the case of calcium carbonate, a maximum inhibition value of 30% was obtained.