Metathesis-Based Monoliths: Influence of Polymerization Conditions on the Separation of Biomolecules

Monolithic materials were prepared by transition metal-catalyzed ring-opening metathesis copolymerization of norborn-2-ene and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endodimethanonaphthalene within the confines of surface-derivatized borosilicate columns in the presence of the porogenic solvents toluene and 2-propanol using Cl2(PCy3)2Ru(=CHPh) (1) as initiator. Relevant physicochemical data of the porous structure (specific surface area (sigma), pore volume (Vp), volume fraction of pores (epsilonp), and intermicroglobule volume (epsilonz)) of the monolithic columns were determined by inverse size exclusion chromatography in tetrahydrofuran. Mean particle diameters were determined via electron microscopy. The influence of variations in polymerization conditions in terms of stoichiometry of the monomers and porogenic solvents on the chromatographic separation of the oligodeoxynucleotides dT12-dT18 and eight model proteins (ribonuclease A, insulin, cytochrome c, lysocyme, alpha-lactalbumin, alpha-chymotrypsinogen, beta-lactoglobulin B, catalase) were studied. Also, the role of additional phosphine on the entire polymerization setup and the associated chromatographic separations was elucidated. Relevant chromatographic data as well as differences between the separation of oligodeoxynucleotides and proteins may directly be attributed to the above-mentioned physicochemical properties of the metathesis-based monoliths. Finally, DSC-TGA-MS investigations on various monoliths of different composition and age were carried out in order to provide information on stability and oxidation behavior.