Aryl Acrylate Based High-Internal-Phase Emulsions as Precursors for Reactive Monolithic Polymer Supports PETER KRAJNC, 1,2 DEJAN S ˇ TEFANEC, 1 JANE F. BROWN, 2 NEIL R. CAMERON 2 1 Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia 2 Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, United Kingdom Received 28 July 2004; accepted 3 September 2004 DOI: 10.1002/pola.20501 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Water-in-oil high-internal-phase emulsions (HIPEs), containing 4-nitro- phenyl acrylate and 2,4,6-trichlorophenyl acrylate as reactive monomers, were pre- pared and polymerized, and highly porous monolithic materials resulted. The novel materials were studied by combustion analysis, Fourier transform infrared spectros- copy scanning electron microscopy, mercury porosimetry, and N 2 adsorption/desorption analysis. With both esters, cellular macroporous monolithic polymers were obtained; the use of 4-nitrophenyl acrylate resulted in a cellular material with void diameters between 3 and 7 m and approximately 3-m interconnects, whereas the use of 2,4,6-trichlorophenyl acrylate yielded a foam with void diameters between 2 and 5 m, most interconnects being around 1 m. The resulting monoliths proved to be very reactive toward nucleophiles, and possibilities of functionalizing the novel polymer supports were demonstrated via reactions with amines bearing additional functional groups and via the synthesis of an acid chloride derivative. Tris(hydroxymethyl)amin- omethane and tris(2-aminoethyl)amine derivatives were obtained. The hydrolysis of 4-nitrophenylacrylate removed the nitrophenyl group, yielding a monolithic acrylic acid polymer. Furthermore, functionalization to immobilized acid chloride was performed very efficiently, with more than 95% of the acid groups reacting. The measurement of the nitrogen content in 4-nitrophenyl acrylate poly(HIPE)s after various times of hydrolysis showed the influence of the total pore volume of the monolithic polymers on the velocity of the reaction, which was faster with the more porous polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 296 –303, 2005 Keywords: foams; functionalization of polymers; high-internal-phase emulsions; macroporous polymers; monolithic polymers INTRODUCTION Since their glamorous introduction into synthetic chemistry via Merrifield’s peptide synthesis in 1963, polymer supports have been developed to a huge degree. 1 The majority of the synthetic pro- cesses involving polymer supports described so far use polymer beads prepared by suspension polymerization. Because of the relative ease of preparation and the possibility of controlling the size distribution, many types of polymer beads are now available commercially. However, some characteristics of bead-type supports limit their use, especially in a flow-through context, which is considered an advantageous method for conduct- ing supported synthesis. 2 In the case of gel-type beads, swelling of the particles is necessary for reactive sites to become accessible. This requires the use of an appropriate solvent for the process Correspondence to: P. Krajnc (E-mail: peter.krajnc@uni- mb.si) or N. R. Cameron (E-mail: n.r.cameron@durham.ac.uk) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 43, 296 –303 (2005) © 2004 Wiley Periodicals, Inc. 296