Investigations of polymer dynamics in nanoporous media by field cycling NMR relaxometry and the dipolar correlation effect

The chain dynamics of short-chain perfluoropolyether melts confined in Vycor nanoporous media has been characterized by field cycling nuclear magnetic resonance relaxometry and the dipolar correlation effect. The slowdown of motions under confinement, leading to larger residual dipolar couplings, has been probed by looking at the quotient of stimulated and primary echoes. Using field cycling rclaxornetry, it has been shown that there is strong evidence of reptation-like motion, even for such short-chain polymers as shogun by die frequency and molecular weight dependences of the spin lattice relaxation time. (C) 2007 Elsevier Inc. All rights reserved.