Effects of structure on the performance of latex nanoparticles as a pseudostationary phase in electrokinetic chromatography

The fundamental relationships between the structure and chemistry of latex nanoparticles synthesized by reversible addition fragmentation chain transfer (RAFT) controlled living polymerization and their subsequent performance as pseudostationary phases (PSP) are reported in this paper. RAFT enables the rational optimization of latex nanoparticle pseudostationary phases and control of the behavior of the PSP. Nanoparticles comprised of amphiphilic diblock copolymers of 2-acrylamido-2-methylpropane sulfonic acid-derived ionic/hydrophilic blocks and butyl- ethyl- or methyl-acrylate-derived hydrophobic blocks were synthesized in two sizes. The mobility, methylene selectivity, and efficiency of each of the six pseudostationary phases are reported, as well as the relationship between monomer quantity and NP size. Linear solvation energy relationships are reported and compared to SDS micelles and previous nanoparticle pseudostationary phases. The solvation characteristics and selectivity of nanoparticle pseudostationary phases is shown to be affected primarily by the structure of the hydrophobic copolymer block. Butyl acrylate nanoparticles 17 nm in diameter are found to provide the best overall separation performance with over 500 thousand theoretical plates generated in 6 min separations.