POLYMERIC SELF-ASSEMBLED MONOLAYERS .2. SYNTHESIS AND CHARACTERIZATION OF SELF-ASSEMBLED POLYDIACETYLENE MONOLAYERS AND MULTILAYERS

We report the synthesis and characterization of self-assembled mono- and multilayers of omega-functionalized diacetylenic thiols. We used the carboxylic acid-terminated alkanethiol diacetylene HS(CH2)(10)C=CC=C(CH2)(10)-COOH as a block for preparing multilayers. Individual layers are covalently bonded through a thioester linkage. These two orthogonal polymerization steps yield a highly structured three-dimensional, surface-confined polymer. The results of infrared external reflectance spectroscopy and ellipsometry clearly indicate layer-by-layer growth up to at least 6 layers. The multilayers can be polymerized by UV irradiation either after the deposition of each individual layer or after all layers are deposited. The appearance of bands attributable to C=C vibrational modes in resonance Raman spectra confirms polymerization. Transmission UV-vis spectroscopy indicates the films consist of the highly conjugated blue polydiacetylenic polymer, and that polymerization is complete within 5 min of initial irradiation.