Determination of Water-Polymer Interactions in Micro-Porous Polymers by Low Resolution NMR Spin -Spin Relaxation Time Measurements

Since many years, Nuclear Magnetic Resonance (NMR) relaxation (7y techniques have been used prolifically in study of surface interaction at the liquid/solid interface of micro- structurally complex materials. In the first part of this study, polyHLPE polymers (PHPs) were utilized to demonstrate the effects of water absorption on the NMR T2 measurement. PHPs used in this experiment were prepared from styrene, divinyl benzene and sorbiton monoleate. In the second part of this work, different molecular weight polyethylene glycols (PEG) and polyethylene oxide (PEO) were used. These powder form polymers were laboratory-grade chemicals. Since both are relatively soluble in water, aqueous polymers solutions were prepared in five different concentrations namely 1%, 5%, 10%, 15% and 20% (by weight). In this study, T2 relaxation for the PHPs have yielded a narrow distribution while the PEG polymers have given a very wide distribution of the relaxation times. Also, for the PHPs, it is shown that the distribution of T 2 shifts towards higher values (longer time) as water content increases. In the case of water soluble polymers (PEG and PEO), similar results are obtained where the shift to higher T2 values requires higher water content