Effect of pH and salt on the stiffness of polyelectrolyte multilayer microcapsules
Effect of pH and salt on the stiffness of polyelectrolyte multilayer microcapsules
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DOI：
10.1021/la049934h
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发表时间：
2004-03-30
期刊：
影响因子：
3.9
通讯作者：
Vinogradova, OI
中科院分区：
文献类型：
--
作者：
Lulevich, VV;Vinogradova, OI
通过使用原子力和共聚焦显微镜的组合，我们探讨了pH值和盐的刚性的聚阴离子和弱聚阳离子组成的外壳的微胶囊的效果。发现胶囊的刚度在水中最大。它会随着盐的加入而略微降低，并且在酸性和碱性溶液中都会变得更小。胶囊在电解质溶液中的适度软化表明，即使是高盐浓度也不会显着解离多层中的聚电解质。胶囊在高pH值下的急剧软化可能反映了聚阳离子的电荷密度的降低，这导致离子交联数量的减少。相比之下，在酸性溶液中的胶囊的低刚度似乎主要与多层壳的增强的渗透性有关。
By using a combination of atomic force and confocal microscopy, we explore the effect of pH and salt on the stiffness of polyelectrolyte microcapsules with shells composed of strong polyanions and weak polycations. The stiffness of the capsules was found to be largest in water. It decreases slightly with added salt and gets much smaller both in acidic and in alkaline solutions. The moderate softening of the capsules in electrolyte solutions indicates that even high salt concentration does not significantly dissociate polyelectrolytes in the multilayer. The dramatic softening of the capsules at high pH probably reflects a decrease in the charge density of a polycation, which leads to a reduction in the number of ionic cross-links. In contrast, low stiffness of the capsules in acidic solutions seems to be connected mostly with the enhanced permeability of the multilayer shell.