通过现场圆测量研究的多层聚酸的稳定性:干燥和积聚后温度和pH值变化的影响
Tobias J Halthur1, Per M Claesson, Ulla M Elofsson
1YKI, Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden. tobias.halthur@surfchem.kth.se
Journal of the American Chemical Society
|December 23, 2004
概括
用聚L-胺酸 (PGA) 和聚L-氨酸 (PLL) 构建的多电解质多层 (PEM) 在干燥和重新湿时呈现可逆的厚度变化. 然而,pH值和温度的变化会导致不可逆转的变化和歇斯底里,影响薄膜的稳定性.
科学领域:
- 材料科学 材料科学 材料科学
- 表面化学 表面化学
- 聚合物科学 聚合物科学
背景情况:
- 聚电解质多层 (PEM) 是使用层次组装 (LbL) 制造的多功能材料.
- 了解PEM在各种环境条件下的稳定性对于其应用至关重要.
研究的目的:
- 研究由聚L-胺酸 (PGA) 和聚L-氨酸 (PLL) 组成的PEM薄膜在和表面的现场稳定性.
- 分析干燥/重新湿,温度周期和pH值变化对PEM厚度和结构的影响.
主要方法:
- 使用逐层 (LbL) 技术制造PEM,初始的聚乙烯胺 (PEI) 层.
- 在不同环境条件下使用圆测量在现场监测薄膜厚度和稳定性.
主要成果:
- 在干燥时,PEM薄膜显示显著的厚度减少 (~70%),在重新湿时完全可回收,允许持续的薄膜积累.
- 在干燥状态下,薄膜厚度对环境湿度高度敏感,需要数小时才能平衡.
- 温度和pH值的变化导致可逆的胀 (高达8%) 和脱水 (分别为10-20%).
- pH诱导的厚度变化表现出歇斯底里,表明不可逆转的结构变化.
结论:
- 膜在干燥/重新湿周期后具有良好的可逆性,适合进一步的层沉积.
- 湿度,温度和pH值等环境因素显著影响PEM稳定性和结构.
- 在pH响应中观察到的hysteresis表明了受控结构修改和需要记忆效应的应用的潜力.
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