Interactions of binary liquid mixtures with polysaccharides studied using multi-dimensional NMR relaxation time measurements

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• 作者：J. Kolz ; Y. Yarovoy ; J. Mitchell ; M.L. Johns ; L.F. Gladden
• 关键词：Starch ; Water– ; glycerol mixture ; T₂– ; T₂ exchange
• 刊名：Polymer
• 出版年：2010
• 出版时间：19 August 2010
• 年：2010
• 卷：51
• 期：18
• 页码：4103-4109
• 全文大小：672 K

文摘

Nuclear magnetic resonance transverse T₂ relaxation time has proven to be a valuable parameter for characterizing liquid/polymer interactions. This measurement is applicable to many food, personal care, and cosmetic products that contain multi-component liquid mixtures. Here, we investigate the interactions of corn starch with water/glycerol mixtures of different weight compositions and explore liquid exchange dynamics; such a system is relevant to the personal care industry. We use a combination of chemical shift resolved ¹H T₂ relaxation measurements and corresponding two-dimensional T₂ relaxation exchange experiments using both a conventional experimental protocol and a modified method with the addition of NMR chemical shift selectivity. Two relaxation regimes were evident for the hydroxyl ¹H (found in both water and glycerol) whilst three relaxation regimes are evident for the aliphatic glycerol ¹H associated here with strongly bound, weakly bound, and free (bulk) liquid, respectively. At higher water contents preferential absorption of glycerol was evident. T₂–T₂ exchange maps with a range of storage times reveal molecular exchange rates between all three regimes due to self-diffusion. Rapid exchange of water between the bulk and bound locations was evident in the case of pure water. Exchange rates for hydroxyl ¹H was considerably reduced by the inclusion of glycerol.