Rhythmic Evaporation Rings of Orange II and Fast Red B

Abstract

IntroductionThe first study of the peculiar structures obtained when two dissolved substances are allowed to react slowly to form a precipitate was made by Rungel in 1865, when he was attempting to add stiffness or rigidity to blotting papers. He conceived the idea of forming precipitates between the fibres of the paper by first saturating the paper with some soluble compound that would later be precipitated by the diffusion of a second soluble compound into the paper. In the course of his investigations he noticed peculiarities in the form and shape of the precipitates, which peculiarities he found to be a function of the rates of diffusion.Ord,* in 1869, accidentally obtained other growth forms when he allowed ammonium oxalate to diffuse into isinglass which was slightly impregnated with calcium chloride. The insoluble calcium oxalate was obtained in some very fantastic forms, quite different from those obtained when the two reacting salts were mixed in solution.While experimenting with diffusion phenomena, Lupton3 noticed that in certain cases layers or rings were produced. However, he merely mentioned their occasional occurrence and did not attempt to investigate them.It remained for Liesegangl in 1896, to report his exhaustive investigations of ring formation in gels. He is the first author to give exact data upon these ring structures, and is among the first to point out t'heir significance in explanation of geological diffusion phenomena. His first preparations were made by placing a drop of silver nitrate solution upon a glass plate that had been coated with gelat,in impregnated with potassium bichromate. This gave a series of concentric rings consisting of insoluble silver chromate, the rings being spaced a t wider intervals apart in proportion as the distance from the center increased.In 1914, E. Kiisters reported and described the rhythmic crystallizations obtained when trisodium orthophosphate, cupric sulfate, ferrous sulfate, potassium ferrocyanide, and ammonium sulfate separated from gelatin solutions on drying at ordinary temperatures. This is thought to be the

Patterned deposition at moving contact lines

“…The field remained active during the following decades (see, e.g., Ref. [25]), and became also important in the context of the assembly of proteins and colloidal particles into crystals (cf. discussions and reviews of the usage of evaporating films and drops in Refs.…”

“…Often the patterns are robust and can be post-processed, e.g., to create double-mesh structures by crossing and stacking two ladder films [42]. A number of investigations focuses on deposition patterns resulting from more complex fluids, such as phase separating polymer mixtures [57]; solutions of the biomolecule collagen [58], liquid crystals [59], dye molecules [25,56,60], dendrimers [61], carbon nanotubes [62][63][64], DNA [65,66], DNA and colloidal particle mixtures [67], lysozyme [68], viruses [43] and graphene [69]; and biofluids like blood [70][71][72]. The latter has potential medical implications as one may learn how illnesses can be detected through simple evaporation experiments on small samples [73].…”

Modelling the formation of structured deposits at receding contact lines of evaporating solutions and suspensions

“…Right column: Corresponding profiles for M = −(3.3, 3.2, 3.1, 2.9, 2.8) × 10 −3 , from top to bottom. in the Krieger-Dougherty law (16). In the thin film literature the value ν = 2 is often used, 59,68 and our standard configuration employs the value ν = 1.575 corresponding to spherical colloidal particles as discussed above following Eq.…”

“…12,13 In fact, crack patterns in sol-gel processes had already been studied somewhat earlier, 14,15 however, we do not consider them here. The related concept of using evaporation at contact lines to assemble colloidal particles or proteins into crystals actually has a longer history -see for example the discussions and reviews by Davies et al 16 , Denkov et al 17 , Adachi and Nagayama 18 , Maenosono et al 19 , Kinge et al 20 .…”

“…31 Often the patterns are robust and can be post-processed, e.g., to create double-mesh structures by crossing and stacking two ladder films. 21 A number of investigations focus on deposition patterns resulting from more complex fluids, such as phase separating polymer mixtures; 32 solutions of DNA, 33,34 collagen, 35 liquid crystals, 36 dye molecules, 16,31,37 dendrimers, 38 carbon nanotubes, 39,40 and graphene; 41 and biofluids like blood. 42,43 The latter has medical implications as it is thought that one may learn how to detect some illnesses by simple evaporation experiments on small samples.…”