School of Physics and Astronomy, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, UK.
School of Physics and Astronomy, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, UK.
J Colloid Interface Sci. 2014 Mar 1;417:317-24. doi: 10.1016/j.jcis.2013.11.039. Epub 2013 Dec 1.
We present an experimental investigation into how altering the inter-particle potential between colloids affects the cracking of a ca. 100 μm film deposited on a hard substrate. The colloidal material used was titanium dioxide (r ≈ 30 nm) in an aqueous solvent with interaction strength being adjusted through alteration of the pH away from the isoelectric point. Stable suspensions were observed to form as surface charging increased. Drop casting was used to demonstrate the flow properties of the suspensions; doctor-bladed strips of suspension were subsequently imaged to capture the drying dynamics. Alteration of the pH between 3 and 4 resulted in significant changes in cracking patterns, with the normalised crack domain area α=√A/h increasing for unstable suspensions (pH 4) and the appearance of order in the initial crack pattern for stable suspensions (pH 3). These results can be unified in terms of the barrier to nucleate a new crack.
我们进行了一项实验研究，探讨改变胶体颗粒之间的相互作用势如何影响沉积在硬基底上的约 100 μm 厚薄膜的开裂。所使用的胶体材料是二氧化钛（r ≈ 30nm）在水性溶剂中，通过改变远离等电点的 pH 值来调整相互作用强度。随着表面电荷的增加，观察到稳定的悬浮液形成。通过滴铸法展示了悬浮液的流动特性；随后对刮刀刮制的悬浮液条带进行成像，以捕获干燥动力学。在 pH 值为 3 到 4 之间的变化导致了开裂模式的显著变化，对于不稳定的悬浮液（pH 值为 4），归一化裂纹域面积 α=√A/h 增加，而对于稳定的悬浮液（pH 值为 3），初始裂纹模式出现了有序性。这些结果可以根据形成新裂纹的势垒来统一。
