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首页> 外文期刊>Journal of Applied Polymer Science >Urea-induced conformational changes of chitosan molecules and the shift of break point of Mark-Houwink equation by increasing urea concentration
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Urea-induced conformational changes of chitosan molecules and the shift of break point of Mark-Houwink equation by increasing urea concentration

机译：尿素浓度引起的尿素诱导的壳聚糖分子构象变化和Mark-Houwink方程断裂点的移动

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摘要

Chitosan solutions of the same 83% degree of deacetylation (DD) but different weight average molecular weights (M(w)s) (78-914 kDa) in 0.01M HCl containing different concentrations of urea (0-6M) were prepared. Intrinsic viscosity ([eta]) and weight average molecular weight (M-w) of chitosan were measured with a capillary viscometer and Light scattering, respectively. Mark-Houwink exponent a was used as the parameter of conformational index. The Mark-Houwink exponent a increased with increasing concentrations of urea. When solutions contained 0, 2, 3, 4, and 6M urea, the value of a increased from 0.715 to 0.839, 0.894, 1.000, and 1.060, respectively. This indicates the occurrence of urea-induced conformational transitions of chitosans. The break point shifted from 223 kDa in solutions containing no urea to 280 kDa in 2M urea solutions, to 362 kDa in 4M urea solutions and further to 481 kDa in 6M urea solutions. (C) 2000 John Wiley & Sons, Inc. [References: 25]
机译：制备的壳聚糖溶液在含有不同浓度尿素（0-6M）的0.01M HCl中具有相同的83％脱乙酰度（DD），但重均分子量（M（w）s）（78-914 kDa）不同。壳聚糖的特性粘度（η）和重均分子量（M-w）分别用毛细管粘度计和光散射法测量。将Mark-Houwink指数a用作构象指数的参数。 Mark-Houwink指数随尿素浓度的增加而增加。当溶液中包含0、2、3、4和6M尿素时，值分别从0.715增加到0.839、0.894、1.000和1.060。这表明发生了脲诱导的壳聚糖构象转变。断裂点从不含尿素的溶液中的223 kDa变为2M尿素溶液中的280 kDa，在4M尿素溶液中的362 kDa，再到6M尿素溶液中的481 kDa。 （C）2000 John Wiley＆Sons，Inc. [参考：25]

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