Facile synthesis of porous monolithic membrane microdevice Hany Hassan El-Feky a , Àngels Cano-Òdena b , Tània Gumí a,n a Departament d'Enginyeria Química, Escola Tècnica Superior d'Enginyeria Química, Universitat Rovira i Virgili, Av. Països Catalans, 26, 43007 Tarragona, Spain b POROMETER, Begoniastraat 17, 9810 Eke, Belgium article info Article history: Received 17 October 2012 Received in revised form 8 February 2013 Accepted 6 March 2013 Available online 2 April 2013 Keywords: Porous polymer monoliths Microfluidic device Microchip Membrane microdevice (S)-ibuprofen abstract Incorporation of membranes into microfabricated devices is a topic of growing interest. Porous monolithic polymers offer the desired characteristics to be used as membrane materials for that purpose. In this work, porous monolithic membranes have been prepared by polymerization through UV irradiation. A mixture of hydroxymethyl methacrylate, 2-aminoethylmethacrylate and ethylene dimethacrylate were used with cyclohexanol and dodecanol, which have the role of porogenic solvents. The membranes have been characterized by scanning electron microscopy (SEM). A monolithic polymer- based membrane with surface area of 1.9 mm 2 was successfully incorporated into a microfabricated device. The membrane microdevice was used for incorporation of lipase enzyme and separation of ibuprofen. The membrane microdevice system showed an enantiomeric excess of ca. 40% of (S)-ibuprofen. & 2013 Elsevier B.V. All rights reserved. 1. Introduction Membrane processes have been increasingly gaining importance as separation techniques in the last decades, since they offer several advantages over traditional methods, such as simplicity in set-up and handling, lower time consumption, they offer a relative cheap technology and they are environmentally respectful [1,2]. Recently, due to the rapid development of microtechnology, hybrid mem- brane microfluidic systems have been explored. These microfluidic systems show promising advantages compared with current mem- brane systems used for separation and analytical processes. These advantages are: speed of response, cost effectiveness, sample handling and reagent mixing (i.e. the use of smaller volume of reagents and raw samples and high area to volume ratio) [3–9]. Nowadays membranes are readily incorporated into microfluidic systems and the use of membranes in microfluidics has been a topic of growing interest. Different approaches have been reported to combine membranes and microfluidics such as direct incorporation of commercial membranes into a poly(dimethylsiloxane) (PDMS) casted device [10], in-situ photo-polymerization of polymeric membranes in microchips [11] and coupling of a nanospray micro- chip with a poly(vinylidene difluoride) (PVDF) membrane [12]. Other approaches that have been explored and there are some examples available in the literature [1,9]. Over the last decade, porous monolithic polymer materials have been developed to provide special properties for analytical applications. They have been used within microfluidic devices for applications such as enzyme immobilization [13,14]. Monoliths used for microfluidic devices can be easily fabricated or modified to have a wide variety of functionalities. Some examples are the fabrication of simple and efficient micromixers [15], the prepara- tion of microfluidic devices for solid-phase extraction [16,17]. Polymerization of a mixture that typically contains monomers, free-radical initiator and porogenic solvents leads to porous monolithic polymer materials with large through-pores that enable flow-through applications [18]. Therefore they can be considered as promising membrane materials. The pore size distribution of the porous monolithic materials during the poly- merization process can be controlled by many parameters. The most important ones are generally thought to be the concentration of the cross-linking monomer and the ratio and the type of the porogenic solvents in the polymerization mixture and the poly- merization temperature [19–21]. The ratio of mono-functional, i.e. monomer, over the difunctional compound, i.e. crosslinker, is of utmost significance. The more crosslinking agent is present, the higher the degree of crosslinking will be at early stages of the polymerization [18]. Due to the chemical characteristics, e.g. functionality, and physical characteristics (porosity and high mechanical strength) of the porous monolithic polymer, they can be tailored by selecting the appropriate constituents of the polymeric solution. Moreover they show fast mass transport which results in ultimately better analytical performance com- pared to other conventional media [22]. In general, the immobilization of an enzyme in a membrane improves its stability, and the separation of products by mem- branes simplifies the downstream processing steps and promotes Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/memsci Journal of Membrane Science 0376-7388/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.memsci.2013.03.008 n Corresponding author. Tel.: +34 977559617; fax: +34 977559621. E-mail address: tania.gumi@urv.cat (T. Gumí). Journal of Membrane Science 439 (2013) 96–102