Magnetic resonance imaging of spatially resolved acrylamide photopolymerization

ZMagnetic resonance imaging was employed to examine spatially and temporally resolved photopolymerization of acrylamide gels. Fast exchange between free and bound water results in single exponential T-2 decay, where 1/T-2 scales linearly with polymer concentration. Measured T(2)s are sensitive to the experimental conditions; however, the 1/T-2 relationship to polymer concentration allows a straightforward interpretation of image contrast changes during photopolymerization. The polymer appears to form at a nearly constant rate until the monomer concentration is significantly depleted. Conventional spin-echo images and quantitative CPMG-weighted spin-echo images were acquired. Photopolymerization of a partially masked sample produced a sharp transition (1 mm width) between polymer and monomer regions of the sample. The image intensity is uniform throughout the illuminated region of the sample, indicating uniform polymer formation. Interrupting the illumination quenches polymer formation. Copyright (C) 2003 John Wiley Sons, Ltd.