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Methods of  Identifying the Rigidity and solvation profile of Bacterial Cellulose hydrogels  and its hemicelluloic counterparts using Solid state NMR Techniques.            
  • Haider Salam
Haider Salam
University of East Anglia
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Abstract

\cite{Uhlin_1995}\cite{Tzvi_2001}\cite{MCCANN_2008}\cite{Kaflak_2008} The structure of Protiated, Deuterated and composite Cellulose hydrogels with plant cell wall (PCW) polysaccharides has been investigated using Solid state NMR. A combination of CP kinetics and Water polarisation transfer (WPT) experiments enabled the identification of structural features of Cellulose Crystallinity/rigidity and solvation profile respectively. The ratio of amorphous to crystalline region increases by 15% thereby decreasing the crystallinity of the Cellulose gel and this connects with the fact that the rigidity of Cellulose-Xyloglucan composite is significantly lower as compared with Bacterial Cellulose Gel as evidenced by AFM studies. (by contrast, Arabinoxylan-Cellulose composite experienced negligible differences in rigidity and crystallinity). These results seem to be paradoxical with CP kinetics results which show that Bacterial Cellulose gel and its Hemicelluloic Composites all exhibit High and relatively similar degree of rigidity. This indicates that the rigid components for all of the hydrogels remain at the same degree of rigidity but ratio of rigid to non-rigid components in the hydrogel changes and these changes of crystallinity at the nanostructure have compounded effects on the rigidity of the microstructure. These results highlight the potential Solid State NMR has to probe the multi-scale architecture of Cellulose hydrogels and to observe changes to that structure once hemicelluloses are added to it.  \cite{P_rez_Hern_ndez_2012}\cite{Kolodziejski_2010}\cite{Renard_1999}