Cellulose fibers have properties that make them a promising renewable resource for creating strong composite materials. A weakness of cellulose-based materials is, though, that their advantageous properties are seriously affected when coming in contact to water. One contributing reason for this effect is the relatively high density of hydroxyl groups on the fiber surface through which water can modulate fiber-fiber interactions. If the state of the surface hydroxyl groups were characterized better, it should be possible to develop a better understanding of how to minimize the effect of water in cellulose composites. Traditionally, deuterium (2H) NMR studies of cellulose assessed molecular mobility by detecting the motionally averaged 2H spectrum. Here, we demonstrate using 2H magic-angle-spinning (MAS) NMR to access different populations of hydroxyl groups at the surface of 2H-exchanged cellulose fibers. The cellulose fibers are initially equilibrated in 2H2O atmosphere of controlled humidity and then dried in a highly controlled manner so as to avoid contact with ambient H2O. This process replaces the hydrogens of the accessible hydroxyl groups by 2H. Different surface hydroxyl groups with distinct molecular mobility are then observed by their response in inversion recovery experiments with 2H MAS NMR detection.

Identifying different hydroxyl populations in cellulose by 2H MAS NMR

249th National Meeting (2015)

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