Molecularly imprinted polymer membranes for substance-selective solid-phase extraction from water by surface photo-grafting polymerization

Hydrophilized polyvinylidene fluoride microfiltration membranes were surfac e-modified in the presence of a template (terbumeton) in methanol with a gr aft copolymer of a functional monomer (2-acrylamido-2-methyl-1-propane sulf onic acid, AMPS, methacrylic acid, MAA, or acrylic acid, AA) and a cross-li nker (N,N'-methylene-bis-acryiamide) using UV irradiation and benzophenone as photoinitiator. As result, membranes covered with a thin layer of imprin ted polymer selective to terbumeton were obtained. Blank membranes were pre pared with the same monomer composition, but in the absence of the template . The membranes' capacity to adsorb terbumetone from aqueous solution was e valuated yielding information regarding the effect of polymer synthesis (ty pe and concentration of functional monomer, concentration of cross-linker) on the resulting membranes' recognition properties. UV spectroscopic studie s of the interactions with terbumetone revealed that AMPS forms a stronger complex than MAA and AA. In agreement with that finding, imprinting with AM PS Save higher affinities than with MAA and AA. The terbumeton-imprinted me mbranes showed significantly higher sorption capability to this herbicide t han to similar compounds (atrazine, desmetryn, metribuzine). With the novel surface modification technology, the low non-specific binding properties o f the hydrophilized microfiltration membrane could successfully be combined with the receptor properties of molecular imprints, yielding substance-spe cific molecularly imprinted polymer composite membranes. The high affinity of these synthetic affinity membranes to triazine herbicides together with their straightforward and inexpensive preparation provides a good basis for the development of applications of imprinted polymers in separation proces ses such as solid-phase extraction. (C) 2001 Elsevier Science B.V. All righ ts reserved.