For certain commercial applications such as enhanced oil recovery, sterically-stabilized colloidal dispersions that exhibit extreme salt tolerance are desirable. Herein we report a series of cationic nano-objects that display high colloidal stability in highly salty aqueous media. More specifically, various binary mixtures of poly(N’N-dimethylacrylamide) (PDMAC) and poly(2-(acryloyloxy)ethyl trimethylammonium chloride) (PATAC) chains were chain-extended with diacetone acrylamide (DAAM) via reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization at 70 °C to produce (n PATACx + 1-n PDMACy) - PDAAMz diblock copolymer nano-objects at 20 % w/w solids via polymerization-induced self-assembly (PISA). TEM analysis confirms that systematic variation of the mean degrees of polymerization (x, y and z) of each block and the mole fraction of the cationic PATAC (n) enables the formation of well-defined cationic spheres, worms or vesicles. The cationic character of the spheres can be tuned simply by varying the mole fraction of PATAC (n) for fixed x, y and z values, as indicated by aqueous electrophoresis. SAXS analysis indicates that the mean diameter can be adjusted by varying z (for fixed n, x and y). Remarkably, dynamic light scattering studies confirmed that highly cationic spheres prepared using PATAC as the sole steric stabilizer remained well-dispersed in the presence of 4 M KCl. Similarly, cationic worms and vesicles prepared using binary mixtures of PATAC and PDMAC remained stable up to 1 M KCl. Such systems are expected to be useful models for understanding the behavior of aqueous colloidal dispersions in the presence of high salt.

New cationic sterically-stabilized diblock copolymer nanoparticles exhibit exceptionally high salt tolerance in aqueous media

2019 Fall National Meeting

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