Mauser Tatjana, Déjugnat Christophe, Sukhorukov Gleb B
Max Planck Institute of Colloids and Interfaces, Wissenschaftspark Golm, 14424 Potsdam, Germany.
J Phys Chem B. 2006 Oct 19;110(41):20246-53. doi: 10.1021/jp063502t.
A detailed study of the role of solution pH and ionic strength on the swelling behavior of capsules composed of the weak polyelectrolytes poly(4-vinylpyridine) (P4VP) and poly(methacrylic acid) (PMA) with different numbers of layers was carried out. The polyelectrolyte layers were assembled onto silicon oxide particles and multilayer formation was followed by zeta-potential measurements. Hollow capsules were investigated by scanning electron microscopy and atomic force microscopy. The pH-dependent behavior of P4VP/PMA capsules was probed in aqueous media using confocal laser scanning microscopy. All systems exhibited a pronounced swelling at the edges of stability, at pHs of 2 and 8.1. The swelling degree increased when more polymer material was adsorbed. The swollen state can be attributed to uncompensated positive and negative charges within the multilayers, and it is stabilized by counteracting hydrophobic interactions. The swelling was related to the electrostatic interactions by infrared spectroscopy and zeta-potential measurements. The stability of the capsules as well as the swelling degree at a given pH could be tuned, when the ionic strength of the medium was altered.
对溶液pH值和离子强度对由不同层数的弱聚电解质聚（4-乙烯基吡啶）（P4VP）和聚（甲基丙烯酸）（PMA）组成的胶囊溶胀行为的作用进行了详细研究。将聚电解质层组装到氧化硅颗粒上，并通过ζ电位测量跟踪多层的形成。通过扫描电子显微镜和原子力显微镜对中空胶囊进行了研究。使用共聚焦激光扫描显微镜在水性介质中探测了P4VP/PMA胶囊的pH依赖性行为。所有体系在稳定性边缘（pH值为2和8.1时）均表现出明显的溶胀。当吸附更多聚合物材料时，溶胀度增加。溶胀状态可归因于多层内未补偿的正电荷和负电荷，并通过抵消疏水相互作用而稳定。通过红外光谱和ζ电位测量将溶胀与静电相互作用相关联。当改变介质的离子强度时，可以调节胶囊的稳定性以及在给定pH值下的溶胀度。
