Macroscopic pattern formation of liquid crystal in κ-carrageenan gel

Abstract

A macroscopic pattern consisting of liquid crystal layers in hydorgel is self-organized. The pattern forms when potassium ion diffuses into a κ-carrageenan solution from one end of the glass capillary that contains the κ-carrageenan solution. Both the distance between two adjacent liquid crystalline layers (spacing, x n+1 − x n ,) and thickness of liquid crystalline layers (width, w n ) depend linearly on the distance from the diffusing end of the potassium ion x n . The time prior to the formation of the nth liquid crystalline layer t n depends linearly on x n 2 . In addition, the spacing coefficient p is inversely proportional to the concentration of potassium ions. These results are in good agreement with the Liesegang phenomenon. In this system the κ-carrageenan solution behaves as a supporting medium for the spatial pattern, as well as the pattern forming substance. The lower values of p, rather than the common Liesegang pattern, in this system could be attributed to the large molecular weight of the κ-carrageenan–potassium complex. The pattern consisted of discrete liquid crystal phases must be formed due to the much larger diffusion constant of potassium ion (diffusant) than that of κ-carrageenan (product).