Controlling the Rate of Water-Induced Switching in Mechanically Dynamic Cellulose Nanocrystal Composites
Controlling the Rate of Water-Induced Switching in Mechanically Dynamic Cellulose Nanocrystal Composites
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DOI：
10.1021/ma4008187
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发表时间：
2013-10-22
期刊：
影响因子：
5.5
通讯作者：
Rowan, Stuart J.
中科院分区：
文献类型：
--
作者：
Dagnon, Koffi L.;Way, Amanda E.;Rowan, Stuart J.
羧基化纤维素纳米晶体具有不同的电荷密度，范围从约。通过用不同当量的丙胺部分官能化1100 mmol/kg羧化的CNC来制备270至约1100 mmol/kg的羧化的CNC。将这些不同电荷的纳米填料并入聚（乙酸乙烯酯）中产生了一系列水响应性机械适应性纳米复合材料。纳米复合材料样品的动态力学分析和流变学研究表明，水溶胀度和机械软化率与CNC电荷密度有关。然而，有趣的是，纳米复合材料的机械性能，无论是干燥的还是完全溶胀的，或多或少与CNC纳米填料的电荷密度无关。因此，这些结果突出了一种在不显著影响其机械性能的情况下调整机械转换（或水通过纳米复合材料的扩散）速率的方法。
Carboxylated cellulose nanocrystals with varying charge densities, ranging from ca. 270 to -1100 mmol/kg, were prepared via partial functionalization of 1100 mmol/kg carboxylated CNCs with different equivalents of propylamine. Incorporation of these differently charged nanofillers into poly(vinyl acetate) produced a series of water-responsive mechanically adaptable nanocomposite materials. Dynamic mechanical analysis and rheological studies of the nanocomposite samples indicated that both the degree of water swelling and the rate of mechanical softening are related to the CNC charge density. Interestingly, however, the mechanical properties of the nanocomposites, either dry or fully swollen, are more-or-less independent of the charge density of the CNC nanofillers. Thus, these results highlight a method to tailor the rate of mechanical switching (or diffusion of water through the nanocomposite material) without significantly impacting its mechanical properties.