Department of Physics and Surrey Materials Institute, University of Surrey, Guildford, Surrey, United Kingdom.
ACS Appl Mater Interfaces. 2009 Mar;1(3):631-9. doi: 10.1021/am800179y.
Polymer colloids are often copolymerized with acrylic acid monomers in order to impart colloidal stability. Here, the effects of the pH on the nanoscale and macroscopic adhesive properties of waterborne poly(butyl acrylate-co-acrylic acid) films are reported. In films cast from acidic colloidal dispersions, hydrogen bonding between carboxylic acid groups dominates the particle-particle interactions, whereas ionic dipolar interactions are dominant in films cast from basic dispersions. Force spectroscopy using an atomic force microscope and macroscale mechanical measurements show that latex films with hydrogen-bonding interactions have lower elastic moduli and are more deformable. They yield higher adhesion energies. On the other hand, in basic latex, ionic dipolar interactions increase the moduli of the dried films. These materials are stiffer and less deformable and, consequently, exhibit lower adhesion energies. The rate of water loss from acidic latex is slower, perhaps because of hydrogen bonding with the water. Therefore, although acid latex offers greater adhesion, there is a limitation in the film formation.
聚合物胶体通常与丙烯酸单体共聚，以赋予胶体稳定性。在这里，报道了 pH 值对水基聚（丙烯酸丁酯-丙烯酸）薄膜纳米级和宏观粘附性能的影响。在从酸性胶体分散体浇铸的薄膜中，羧酸基团之间的氢键主导着颗粒-颗粒相互作用，而在从碱性分散体浇铸的薄膜中，离子偶极相互作用占主导地位。原子力显微镜的力谱和宏观力学测量表明，具有氢键相互作用的乳胶膜具有更低的弹性模量和更大的可变形性。它们产生更高的粘附能。另一方面，在碱性乳胶中，离子偶极相互作用增加了干燥薄膜的模量。这些材料更硬、更不易变形，因此表现出较低的粘附能。酸性乳胶的水分流失速度较慢，这也许是因为与水形成氢键。因此，尽管酸性乳胶具有更大的粘附力，但在薄膜形成方面存在限制。
