Observation of the internal network structure of a polymer-stabilized liquid crystal via transmission electron microscopy

The internal structure of the network component of a polymer-stabilized liq uid crystal has been observed for the first time. These are systems in whic h a small amount of a monomer is dissolved within a LC host and then polyme rized in situ to produce a network. Studies performed on a system prepared using the diacrylate monomer RM60 and the nematic mixture BL087 are present ed. The concentration of the monomer was I wt %. After formation of the net work through photopolymerization of the monomer between Melinex layers with in a glass cell, the LC host was removed by dissolving it in heptane. Subse quent observation of the internal network structure by transmission electro n microscopy was made possible by bromine staining of the network, followed by embedding and ultramicrotomy. A collection of solid, near-circular obje cts was observed, of mean diameter 0.13 mu m. These objects were found to b e highly permeable to bromine vapour, suggesting an open, but homogeneous s tructure.