FUNCTIONALIZATION OF NANOCHANNELS BY GRAFTING POLYMERIZATION ON PET TRACK-ETCHED MEMBRANES

SILVIA SOTO ESPINOSA; CLAUDIA ARBEITMAN; MARIE CLOUDE CLOCHARD; MARIANO GRASSELLI

Cracovia

Simposio; 10th meeting of the Ionnizing Radiation and Polymer Symposium; 2012

IRaP IAEA

Track-etched membranes are a special kind of membranes were pores are build ’one per one’ by swift-heavy ions bombardment onto polymeric films. Latent tracks made by particle bombardment are subsequent etched with specific chemical reagents according to the chemical structure of the trunk polymer. Unique properties of these membranes, very narrow pore size distribution and controlled pore number per area have specific applications in biology area. Track-etched membranes are currently commercial products useful for cell separation and air monitoring, cell biology, and liposome preparation by lipid extrusion. Novel application to nanotechnology such us to prepare nanowires, nanofilters and sensors for special usage has been reviewed [1]. In addition, single-ion nanochannels and nanowires fabrication are currently possible [2]. In the progress of the chemical etching the damaged region is dissolved by hydrolyzing polymer chains, reaching pore diameters in the range of nano to micrometer scale. After the etching procedure on irradiated polymer still there are enough active sites left that can be used to initiate a polymerization process. In this way, grafting polymerization in the track pores can be performed selectively. Acrylic acid has been polymerized onto the pore wall of track-etched membranes of polypropylene and PVDF [3,4]. In this work track-etched polyethylene terephthalate (PET) membrane has been grafted onto nanopore walls with the reactive glycildyl methacrylate (GMA) monomer. To visualize the grafting yield we used very sensitive techniques such as Field Emission SEM (FESEM) and fluorescent methods. Grafting was performed with 10% GMA solution at 62 C under nitrogen atmosphere in the range of 15 min to 24 h. Epoxy groups from grafted polyGMA were revealed by covalent link to fluorescein and measured directly by the spectrofluorometer Nanodrop® 3300. Fluorescent relative units (RFU) increase up to four hours of grafting time. This result was also confirmed by fluorescence microscopy and confocal microscopy where fluorescence signals were restricted to pore regions. Using a PET foil with the same ion fluence, we found a direct correlation between RFU and pore diameter between 50 and 540 nm. Taking into account a functional membrane property, a reduction in solute permeability of grafted membranes was analyzed by molecular diffusion of fluorescent probes. References 1. A. Waheed, D. Forsyth, A. Watts, A.F. Saad, G.R. Mitchell, M. Farmer, P.J.F. Harris (2009); Radiat. Meas. 44, 1109. 2. R. Spohr, C. Zet, B. E. Fischer, H. Kiesewetter, P. Apel, I. Gunko, T. Ohgai, L. Westerberg (2010); NIMBS B 268, 676. 3. O. Cuscito, M.-C. Clochard, S. Esnouf, N. Betz, D. Lairez (2007); NIMBS B 265, 309. 4. R. Mazzei, G. García Bermúdez, V.C. Chappa, M.F. del Grosso, A. Fernandez (2006); NIMBS B 251, 99.