Micellar aggregation of poly(acrylamide-co-styrene): Towards ‘self-removing’ polymers from solution

Polymer drag reducing agents (DRAs) are used in hydraulic fracturing processes to reduce frictional drag developed in fully turbulent pipe-flows. The drag reduction lowers energy consumption required to pump fluids. Removal and/or recovery of DRAs from the fracking fluids remains challenging causing environmental issues. We used model aqueous hydraulic fracturing fluids containing poly(acrylamide-co-styrene) P(AAm-co-St) as DRA and demonstrate an approach to ‘self-remove’/recover the P(AAm-co-St) copolymers by up to 55%. This approach involves foaming of P(AAm-co-St) solutions by sparging gas into fluid (at application relevant conditions) resulting in copolymer enrichment in a generated foam phase and subsequent removal from solution. Our observations suggest a simple method to remove or recover DRAs after drag reduction applications from fracking fluids. Liquid foams containing the P(AAm-co-St) copolymer were dried and redissolved in water offering the potential to be reused for further drag reduction applications or, in case of waste, explored for other applications as emulsifier or in macroporous materials.