Molecular motion of small molecules in cellulose gels studied by NMR

Measurements of relaxation times, T₁ and T₂, and self-diffusion coefficients, D, for small molecules, viz., H₂O, dioxane and t-butanol, in the gel system cellulose/H₂O are reported and compared with those for H₂O in a polyacrylamide gel of the same polymer content. The temperature dependence of T₁ and D can for all the penetrants be represented by Arrhenius type relations which merely are parallel shifts by the same amount, towards smaller values, of those obtained without polymer. The T₂ values for H₂O in both gels pass through a shallow minimum over the considered temperature interval (14°?44°C). Furthermore, relaxation times T₁ of D₂O in the gel system cellulose/D₂O are reported; in a plot of ln T₁ vs. 1/T, a plateau region is observed at higher temperatures.