New “one-step” method for the simultaneous synthesis and anchoring of organic monolith inside COC microchip channels

Abstract

A new method for monolith synthesis and anchoring inside cyclic olefin copolymer (COC) microchannels in a single step is proposed. It is shown that type I photoinitiators, typically used in a polymerization mixture to generate free radicals during monolith synthesis, can simultaneously act as type II photoinitiators and react with the plastic surface through hydrogen abstraction. This mechanism is used to "photograft" poly(ethylene glycol) methacrylate (PEGMA) on COC surfaces. Contact angle measurements were used to observe the changes in surface hydrophilicity when increasing initiator concentration and irradiation duration. The ability of type I photoinitiators to synthesize and anchor a monolith inside COC microchannels in a single step was proved through SEM observations. Different concentrations of photoinitiators were tried. Finally, electrochromatographic separations of polycyclic aromatic hydrocarbons were realized to illustrate the beneficial effect of anchoring on chromatographic performances. The versatility of the method was demonstrated with two widely used photoinitiators: benzoin methyl ether (BME) and azobisisobutyronitrile (AIBN).

A new strategy for simultaneous synthesis and efficient anchorage of polymer monoliths in native PDMS microchips

“…Until now, no work has been devoted to the investigation of the role of PI on the efficiency of monolith polymerization in PDMS microchannels. However, from a point of view of MN anchoring, Ladner et al [38] demonstrated that Type I photoinitiators such as benzoin methyl ether and AIBN, could also act as Type II photoinitiators and abstract hydrogen from a plastic surface. These properties allowed the simultaneous synthesis and anchorage of hexyl and glycidyl acrylate MN inside COC microchannels.…”

Sequence-specific DNA solid-phase extraction in an on-chip monolith: Towards detection of antibiotic resistance genes

“…On the other hand, polypropylene's low reactivity makes anchoring of the monolith more challenging, since attachment of a porous polymer to the wall through covalent bonds is complicated by polypropylene's lack of reactive sites. However, using sufficiently concentrated type I photoinitiators like BME, it is possible to link the monolith to the substrate through hydrogen abstraction, allowing formation of covalent bonds to the polymer network in one step [28]. Monoliths prepared with concentrations of 1%, 2% and 3% BME in the polymerization mixture and exposed for 10, 12 and 15 minutes were evaluated by observing monolith stability in the microfluidic channel under 6 bars applied pressure at 70 °C.…”

Methacrylate Polymer Monoliths for Separation Applications

“…The integration of methacrylate and other monolithic materials into microfluidic devices has benefited both analyte separation and pre-concentration in modular microfluidics as the quest for the miniaturization of chromatographic devices continues [41,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70]. …”