Nanopillar array with multi-scale inter-pillar spacing as chromatography stationary phase support: Theoretical performance evaluation

Abstract

Nanopillar arrays with nanoscale inter-pillar spacing can be fabricated with increasingly high precision in recent years. We propose to use nanopillar arrays with multi-scale inter-pillar spacing to play the role of porous microstructures in columns for pressure driven liquid chromatography. The pattern of the nanopillar array is adjusted to create special “core–shell” or “totally porous” structures with multi-scale ordered pores. We predict the column performance and the pressure drop of the hypothetical columns by a theoretical model with the aid of the pore scale numerical simulation. The prediction indicates that hypothetical columns have better column performance than that of a real column filled with vertically aligned “core–shell” micropillars with ordered inter-pillar pores but disordered intra-pillar pores. We attribute the better performance of hypothetical columns to the multi-scale ordered, size controllable pores in the special “core–shell” or “totally porous” structures. We also investigate the effect of the velocity slip that may occur at hydrophobic nanopillar surfaces and show that further column performance improvement and flow rate enhancement can be expected.