Processing of Polyamides in the Presence of Water via Hydrophobic Hydration and Ionic Interactions
Processing of Polyamides in the Presence of Water via Hydrophobic Hydration and Ionic Interactions
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DOI：
10.1021/ma300459q
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发表时间：
2012-07-24
期刊：
影响因子：
5.5
通讯作者：
Rastogi, Sanjay
中科院分区：
文献类型：
--
作者：
Harings, Jules A. W.;Deshmukh, Yogesh S.;Rastogi, Sanjay
在合成和天然聚酰胺中，酰胺基序的氢键和构象受到离子及其浓度、水分子及其结构以及溶液pH值的强烈影响。该概念与合成脂肪族聚酰胺，特别是尼龙，在高温和相应的蒸汽压下在水中的溶解度相结合，作为这些聚合物加工中的新的可逆屏蔽路线进行评价。到目前为止，可逆屏蔽还不可行，由于缺乏控制所需的活化和去活化的氢键在明智的时刻。在这里，我们表明，在大卤素阴离子的存在下，从无规卷曲状态的结晶被抑制疏水水合，其中快速结晶的尼龙的无定形状态可以保持，即使在20摄氏度。小的水合锂阳离子是有利的，因为它们增强了阴离子的疏水性质。加工后，通过离子在水中的简单迁移促进氢键的完全去屏蔽，这允许恢复所需的构象和结构。过热水
In synthetic as well as natural polyamides, hydrogen bonding and conformations of amide motifs are strongly influenced by the presence of ions and their concentration, water molecules, and their structure, as well as the pH of the solution. This concept combined with solubility of synthetic aliphatic polyamides, in particular nylons, in water at elevated temperature and corresponding vapor pressure is evaluated as a new reversible shielding route in the processing of these polymers. So far, reversible shielding has not been feasible due to a lack in controlling desired activation and deactivation of hydrogen bonding at the judicious moments. Here we show that in the presence of large halogen anions, crystallization from the random coil state is suppressed by hydrophobic hydration, where the amorphous state of the fast crystallizing nylons can be maintained even at 20 degrees C. Small hydrating lithium cations are favored since they strengthen the hydrophobic nature of the anions. Complete deshielding of hydrogen bonding, after processing, is facilitated by simple migration of ions in water that allows recovery of the desired conformation and structure. superheated water