Poly(glycidyl\nmethacrylate-<i>co</i>-ethylene\nglycol dimethacrylate) Monolith with Dual Porosity for Size Exclusion\nChromatography

The use of polymeric monoliths as stationary phases for\nliquid\nchromatography has been limited, despite their ability to enhance\nthe convection flow of the mobile phase with respect to particulate-based\ncolumns. This is due to a poor balance between the volume of flow\nthrough pores and the number of active sites within polymeric monoliths.\nIn this paper, we present the obtainment of poly(glycidyl methacrylate-<i>co</i>-ethylene glycol dimethacrylate) (P(GMA-<i>co</i>-EDMA)) monoliths with dual pore size distributions (with pore sizes\nof 60 and 550 nm). Hierarchical pore size distributions were achieved\nby performing the monolith synthesis by reversible addition–fragmentation\nchain transfer (RAFT) polymerization as well as using ternary porogen\nmixtures (containing PEG, dodecanol, and dioxane). While the controlled\npolymerization mechanism promoted mesopores in the monolith, ternary\nporogen mixtures allowed the formation of macropores. The monoliths\nobtained were used as stationary phases for size exclusion chromatography\n(SEC) for the separation of poly(methyl methacrylate) standards with\nmolar masses between 2.50 × 10<sup>3</sup> and 3.06 × 10<sup>6</sup> g/mol, allowing selectivities that were comparable with commercially\navailable SEC columns packed with porous particles. We believe the\napproach presented in this work could be the first step toward the\nobtainment of stationary phases for SEC with enhanced accessibility\nof exclusion pores. Monolithic columns with accessible porous structures\ncan be beneficial for size-based separations of ultrahigh molar mass\nanalytes with low diffusion coefficients.