High microfluidic polymerization

SIP-driven polymer brush library fabrication leverages the fact that the polymerization initiation species are permanently bound to the substrate. Since the initiators are tethered, controlled delivery of monomer solution to different areas of the substrate results in a grafted polymer library. In NIST work, initiators bound via chlorosilane SAMs to silicon substrates were suitable for conducting controlled atom transfer radical polymerization (ATRP) [53] and traditional UV free radical polymerization [54, 55]. Suitable monomers are delivered in solution to the surface via microfluidic channels, which enables control over both the monomer solution composition and the time in which the solution is in contact with the initiating groups. After the polymerization is complete, the microchannel is removed from the substrate (or vice versa). This fabrication scheme, termed microchannel confined SIP ([t-SIP), is shown in Fig. 10. In these illustrations, and in the examples discussed below, the microchannels above the substrate are approximately 1 cm wide, 5 cm long, and 300-500 [tm high. 

Abstract In sensor and microfluidic applications, the need is to have an adequate solvent resistance of polymers to prevent degradation of the substrate surface upon deposition of sensor formilations, to prevent contamination of the solvent-containing sensor formulations or contamination of organic liquid reactions in microfluidic channels. Unfortunately, no comprehensive quantitative reference solubility data of unstressed copolymers is available to date. In this study, we evaluate solvent-resistance of several polycarbonate copolymers prepared from the reaction of hydroqui-none (HQ), resorcinol (RS), and bisphenol A (BPA). Our high-throughput polymer evaluation approach permitted the construction of detailed solvent-resistance maps, the development of quantitative structure-property relationships for BPA-HQ-RS copolymers and provided new knowledge for the further development of the polymeric sensor and microfluidic components. 

In the following we introduce two key solutions of our platform technology, a concept able to control highly integrated systems containing hundreds or thousands of active polymeric elements and active microfluidic basic components. 

An alternative option to packed channels is the use of monolithic materials, which may have many of the same benefits as packed beds, including high surface area and easily controlled surface chemistry. However, a distinct advantage of monoliths is the ability to prepare them easily and rapidly via polymerization of liquid precursors within the channels of the microdevice without the need for any retaining structures. Despite the popularity of monolithic capillary columns for separations of a variety of low and high molecular weight compounds in HPLC mode, > their first application in microfluidic chips dates back only to 2005. 

In addition to the possibility of using PCSLs to construct microfluidics in various polymeric materials, this approach could also facilitate the implementation of new analysis techniques in a microchip format. For example, applications that require high pressures, such as for loading viscous sieving polymers for DNA separation or for packing small-diameter-particle stationary phases for... 

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