Homeotropic orientation behavior of nematic liquid crystals induced by copper ions

Abstract A homeotropic ordering film of nematic liquid crystal (LC) induced by copper ions (Cu 2+ ) had been developed. The Cu(ClO 4 ) 2 was directly spin-coated on the glass substrate without any other chemical modification. A homeotropic orientation of LC thin-film was generated by the interfacial chemical interaction between nitrile-containing LC and copper ions on the surface. Results showed that an appropriate density of Cu 2+ could shorten the response time of orientation, but a shelf-time was prolonged. The LC film fabrication not only offered a simple process, but also presented a great repeatability to detect organophosphonates (DMMP). This study provided guidance for the design of LC films responding to organic molecules as a biosensor.