Influence of exchange in NMR pore size/relaxation correlation experiments

Abstract

The influence of molecular exchange in porous polymeric systems on experiments that simultaneously correlate and determine pore length scales and surface relaxivities is studied. Pore length scales are determined by taking advantage of the internal field gradients generated by the difference in magnetic susceptibility between the polymer matrix and the contained water, namely the Decay Due to the Internal Field experiment. Transverse relaxation is codified in the detection period thus enabling correlation with the pore length. For the hierarchical very well connected porous polymer system, the considerable molecular exchange of water between different environments renders signals in the two-dimensional maps that make the determination of the surface relaxivity a complex problem.