Traditionally associated with small
molecules,
liquid crystal phases can also form in
polymeric systems.
Liquid crystal polymers (LCPs) may be
classified as
main chain or
side chain LCPs. In the former, the
mesogen is located in the main
backbone of the
polymer. In the latter the
mesogens are
side groups which are attached by one end to the main
backbone of the
polymer.
Sections of the molecule are composed of different substances, and the dissimilar parts of the molecule are immiscible like oil and water. The polymer chains self organise to keep these incompatible microphases separate.
The surface between the different microphases has a high interfacial energy. To reduce this energy the polymer folds itself in such a way as to minimise the interfacial area.
An equilibrium structure is formed that can be complex and repeat in 3 dimensions. The structure can be more complex than the traditional liquid crystals, which typically are ordered in only 1 or 2 dimensions.
Some of these structures are bicontinuous. In this case the two continuous interpenetrating networks of liquid weave in and out of each other in a repeating pattern. The liquids spontaneously organise into two labyrinths related to each other by symmetry and do not mix
The surface separating the two microphases is called the intermaterial dividing surface (IMDS). If the two microphases are present in equal proportion, the surface may be a triply period minimal surface. These surfaces are beautiful to look at and were discovered and analysed by mathematicicans long before they were observed in nature.