Photodeposition technique for restoring holographic films of polydiacetylene

Polydiacetylenes are a very promising class of polymers for both photonic and electronic applications1-3 because of their highly conjugated structures. We, recently, have discovered the possibility of depositing a permanent holographic grating of information, made of polydiacetylene on a glass substrate. A novel technique for obtaining high quality thin films of a polydiacetylene derivative of 2-methyl-4-nitroaniline (PDAMNA) using photodeposition from monomer solutions onto UV transparent substrates was discovered by members of our group a few years back4. This compound was one of several asymmetric diacetylenes that were first studied extensively for their optical and electronic properties by Garito and co-workers in the late 1970s; however, their investigations did not include behavior in solutions5,6. PDAMNA films can be obtained readily from solutions of DAMNA in 1,2-dichloroethane by irradiation with UV light through a quartz or glass window, which serves as the substrate. This simple straightforward process yields transparent films with thickness on the order of 1μm7. To obtain PDAMNA thin films, a solution of DAMNA in 1,2-dichloroethane is placed inside a chamber shown in figure 1. DAMNA monomer strong absorption at 366nm. A hand-held 15W UV lamp placed directly in front of the substrate ( approximate radiation intensity of 800 μW/cm2 at 6 in.), a film of approximately 0.6 μm thickness is obtained after 24 hours of exposure.