H NMR Study of the States of Water in Equilibrium Poly(HEMA-co-THFMA) Hydrogels

Abstract

The spin−spin relaxation times, T₂, of hydrated samples of poly(hydroxymethyl methacrylate), PHEMA, poly(tetrahydrofurfuryl methacrylate), PTHFMA, and the corresponding HEMA−THFMA copolymers have been examined to probe the states of the imbibed water in these polymers. The decay in the transverse magnetization of water in fully hydrated samples of PHEMA, PTHFMA, and copolymers of HEMA and THFMA was described by a multiexponential function. The short component of T₂ was interpreted as water molecules that were strongly interacting with the polymer chains. The intermediate component of T₂ was assigned to water residing in the porous structure of the samples. The long component of T₂ was believed to arise from water residing in the remnants of cracks formed in the polymer network during water sorption.