Abstract:
Hydrophobic coatings from chitosan-surfactant composites (ca. 400 nm thick by UV-Vis spectroscopy) for possible corrosion protection were developed on glass and zinc substrates. The surfactants (sodium dodecyl sulfate, SDS or sodium dodecylbenzenesulfonate, and SDBS) were added to the chitosan by two methods: mixing the surfactants with the aqueous chitosan solutions before film deposition or impregnating the deposited chitosan films with surfactants from their aqueous solutions. For the mixed coatings, it was found that the lower surface tension of solutions (40-45 mN/m) corresponded to more hydrophobic (80-90°) coatings in every case. The hydrophobicity of the impregnated coatings was especially significant (88° for SDS and 100° for SDBS). Atomic force microscopy studies revealed a slight increase in roughness (max 1.005) for the most hydrophobic coatings. The accumulation of surfactants in the layer was only significant (0.8-1.0 sulfur atomic %) in the impregnated samples according to X-ray photoelectron spectroscopy. Polarization and electron impedance spectroscopy tests confirmed better barrier properties for these samples (40-50% pseudo-porosity instead of 94%). The degree of swelling in a water vapor atmosphere was significantly lower in the case of the impregnated coatings (ca. 25%) than that of the native ones (ca. 75%), measured by spectroscopic ellipsometry. Accordingly, good barrier layer properties require advantageous bulk properties in addition to surface hydrophobicity.
摘要:
壳聚糖-表面活性剂复合材料的疏水涂层(约在玻璃和锌基材上开发了用于可能的腐蚀保护的400nm厚的UV-Vis光谱)。表面活性剂(十二烷基硫酸钠,SDS或十二烷基苯磺酸钠,和SDBS)通过两种方法添加到壳聚糖中:在膜沉积之前将表面活性剂与壳聚糖水溶液混合或用其水溶液中的表面活性剂浸渍沉积的壳聚糖膜。对于混合涂层,发现在每种情况下,溶液的较低表面张力(40-45mN/m)对应于更疏水(80-90°)的涂层。浸渍涂层的疏水性尤其显著(对于SDS为88°,对于SDBS为100°)。原子力显微镜研究显示,大多数疏水性涂层的粗糙度略有增加(最大1.005)。根据X射线光电子能谱,浸渍样品中表面活性剂在层中的积累仅是显著的(0.8-1.0硫原子%)。极化和电子阻抗谱测试证实这些样品具有更好的阻隔性能(40-50%的假孔隙率而不是94%)。在浸渍涂层的情况下,在水蒸气气氛中的溶胀程度明显较低(约25%)比本地的(约。75%),用椭圆偏振光谱法测量.因此,除了表面疏水性之外,良好的阻隔层性质需要有利的本体性质。