A New Class of Continuous Polymer Supports Prepared by Ring-Opening Metathesis Polymerization:  A Straightforward Route to Functionalized Monoliths

Functionalized monolithic materials have been prepared by ring-opening metathesis copolymerization of norborn-2-ene (NBE) and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene (DMN-H6) within borosilicate columns in the presence of porogenic solvents such as toluene, methylene chloride, methanol, and 2-propanol. Grubbs-type initiators of the general formula Cl2(PR3)2Ru(CHPh) (R = phenyl, cyclohexyl) were used throughout. The resulting separation media possess microstructures consisting of microporous, spherical microglobules with a narrow microglobule size distribution. By variation of the polymerization conditions in terms of stoichiometry of the monomers, porogenic solvents, and temperature, microglobule diameters may be varied within a range of 2 ± 1 μm up to 30 ± 10 μm. Specific surface areas (σ) and inter-microglobule pore volumes (ε z ) may be altered within 60−210 m2/g and 2−50%, respectively. Nonfunctionalized separation media were successfully used for the separation of 10 different model proteins using reversed phase chromatography. Generally, high flow rates of up to 10 mL/min indicating fast mass transfer may be applied, resulting in fast and efficient separations. Functionalized continuous rods were synthesized by one additional synthetic step that takes advantage of the living character of the ROMP-based copolymerization. This “in situ” derivatization was achieved after the formation of the continuous rod by reacting the active, surface-bound initiator with functional, norborn-2-ene- and 7-oxanorborn-2-ene-based monomers such as endo,endo-7-oxabicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic anhydride (I), endo/exo-7-oxanorborn-2-ene-5-carboxylic acid (II), endo,endo-N,N-norborn-2-ene-5,6-dicarbimid-l-valine-m-nitroanilide (III), exo,exo-N-phenyl-7-oxabicyclo[2.2.1]hept-2-ene-5,6-dicarbimide (IV), exo,exo-N-(4-(N‘,N‘-dimethylaminophenyl)-7-oxanorborn-2-ene-5,6-dicarbimide (X), endo/exo-norborn-2-ene-5-ylmethylhydroxysiloxyl-β-cyclodextrin (XI), and endo/exo-7-oxanorborn-2-ene-5-carboxyl-β-cyclodextrin (XIII), by passing solutions thereof in dichloromethane and DMF over the rigid rod. A β-cyclodextrin-functionalized continuous rod was successfully used for the enantioselective separation of proglumide (β-blocker).