Synthesis of Novel Size Exclusion Chromatography Support by Surface Initiated Aqueous Atom Transfer Radical Polymerization

Abstract

We report the use of aqueous surface-initiated atom transfer radical polymerization (SI-ATRP) to grow polymer brushes from a "gigaporous" polymeric chromatography support for use as a novel size exclusion chromatography medium. Poly(N,N-dimethylacrylamide) (PDMA) was grown from hydrolyzable surface initiators via SI-ATRP catalyzed by 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA)/CuCl. Grafted polymer was characterized semiquantitatively by ATR-FTIR and also cleaved and quantitatively characterized for mass, molecular weight, and polydispersity via analytical SEC/MALLS. The synthesis provides control over graft density and allows the creation of dense brushes. Incorporation of negative surface charge was found to be crucial for improving the initiation efficiency. As polymer molecular weight and density could be controlled through reaction conditions, the resulting low-polydispersity grafted polymer brush medium is shown to be suitable for use as a customizable size exclusion chromatography medium for investigating the principals of entropic interaction chromatography. All packed media investigated showed size-dependent partitioning of solutes, even for low graft density systems. Increasing the molecular weight of the grafts allowed solutes more access to the volume fraction in the column available for partitioning. Compared to low graft density media, increased graft density caused eluted solute probes to be retained less within the column and allowed for greater size discrimination of probes whose molecular weights were less than 10(4) kDa.

The influence of grafted polymer architecture and fluid hydrodynamics on protein separation by entropic interaction chromatography

“…The general synthetic steps for the ATRPbased synthesis of EIC stationary phases are adapted from Jayachandran et al (2002) and Coad et al (2006) as follows. The Toyopearl 1 AF-Amino-650M base matrix (supplied as a gift from Tosoh Biosep Inc., Montgomeryville, PA) was prepared for grafting by converting the surface amine groups into hydroxyl groups by reacting with ring-opening d-gluconolactone in anhydrous solvent (Narain and Armes, 2003).…”

“…Reactions for production of end-grafted PDMA layers by surface-initiated ATRP and saponification by sodium hydroxide. Saponification over time periods of several hours was used to vary the graft density at constant molecular weight according to the method described in Coad et al (2006). Exhaustive cleavage of graft polymer for the purpose of characterization was accomplished by hydrolysis over a 3-week period.…”

A substrate-independent method for surface grafting polymer layers by atom transfer radical polymerization: Reduction of protein adsorption

“…In membrane science, SI-ATRP has been used for the surface modification of filters and membranes composed of polycarbonate [39], nylon [40], porous alumina [41], and fluorinated nanofibres [42] as well as molecular transport through silica-based colloidal films [43]. Finally, in separation science, SI-ATRP has been used as a modifier of chromatographic stationary phases including silica beads [44,45], capillaries [46,47], and beaded polymeric stationary phases [48][49][50].…”

Architecture of polymer particles composed of brush structure at surfaces and construction of colloidal crystals

“…4-Vinylbenzyl N,N-diethyldithiocarbamate (VBDC) was synthesized by the reaction of p-chloromethylstyrene (Seimi Chemical Industry, Tokyo) with N,N-diethyldithiocarbame sodium (Tokyo Kasei Organic Chemicals, Tokyo) in acetone. Details concerning the synthesis and purification of VBDC were given elsewhere [22]. 2,2 0 -Azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70; Wako Pure Chemical Industries, Ltd., Tokyo) and potassium persulfate (KPS; Kanto Chemicals, Tokyo) was purified by crystallization from water.…”

“…We found that photo-induced atom transfer radical polymerization (ATRP) of DC groups in the presence of copper(I) bromide (CuBr)/2,2 0 -bipyridine (bpy) proceeded with living radical mechanism [21]. There are recently reports concerning polymer brush synthesis by grafting-from approach using the radical initiators on the surface by means of ATRP [22,23]. Surface properties can be easily modified by varying the composition of the polymer brush, grafting density, and the degree of polymerization.…”