A novel study of the polymerisation process involved in the formation of the network component of polymer-stabilised liquid crystals within electro-optic cells using high performance liquid chromatography

Polymer-stabilised liquid crystals are systems in which a small amount of m onomer is dissolved within a liquid crystalline host, and then polymerised in situ to produce a network. The progress of the polymerisation, performed within electro-optic cells, was studied by establishing an analytical meth od novel to these systems. Samples were prepared by photopolymerisation of the monomer under well-defined reaction conditions: subsequent immersion in acetone caused the host and any unreacted monomer to dissolve. High perfor mance liquid chromatography was used to separate and detect the various sol utes in the resulting solutions, enabling the amount of unreacted monomer f or a given set of conditions to be quantified. Longer irradiations cause a decrease in the proportion of unreacted monomer since more network is forme d, while a more uniform LC director alignment (achieved by decreasing the s ample thickness) or a higher level of order (achieved by decreasing the pol ymerisation temperature) promotes faster reactions.