RAFT polymerized nanoparticles: Influences of shell and core chemistries on performance for electrokinetic chromatography

The performance and solvation characteristics of two novel latex nanoparticle (NP) pseudo-stationary phases (PSPs) for EKC are determined and compared to those of previously reported micellar, polymeric, and NP materials. The new NPs have shells composed of strongly acidic poly(AMPS) as opposed to the poly(acrylic acid) shell of the prior NP, and have varied hydrophobic core chemistry of either poly(butyl acrylate) or poly(ethyl acrylate). The NPs poly(AMPS) shell shows only minor changes in mobility and selectivity between pH 4.9 and 9.4, allowing adjustment of pH to influence and optimize separation performance. All of the NP phases have significantly different solvation characteristics and selectivity relative to SDS micelles. The selectivity and solvent character are similar for NPs with poly(butyl acrylate) cores and different shells, but vary significantly between NPs with poly(butyl acrylate) versus poly(ethyl acrylate) cores. NPs with poly(butyl acrylate) cores are among the least cohesive PSPs reported to date, while the NP with poly(ethyl acrylate) core is among the most cohesive. The results demonstrate that PSPs with unique selectivity can be generated by altering the chemistry of the hydrophobic core.