Organized multilayers of polydiacetylenes prepared by electrostatic self-assembly

New types of polydiacetylene multilayer are presented. The first type is based on electrostatic self-organization of diacetylene bolaamphiphiles and polyelectrolytes on a charged substrate followed by subsequent ultraviolet (UV) polymerization. The second type is prepared by direct adsorption of a water soluble polydiacetylene and a polyelectrolyte in alternating sequence. The monomeric diacetylenes are of general formula X(CH₂)₉CCC C(CH₂)₉X, with X being a sulfate (1a), phosphate (2) or pyridinium (3) head group. The polydiacetylene (1b) chosen for the multilayer is obtained by γ irradiation of the corresponding diacetylene monomer 1a. It is found that all diacetylene derivatives are well suited for building up self-assembled multilayers and that two of the monomers (1a, 2) can be polymerized on the substrate, while 3 is photo-inactive. The morphology of the multilayers is studied by scanning force microscopy and discussed. The smoothest surface topology is found for multilayers built up from the polydiacetylene 1b and a cationic polyelectrolyte in alternating sequence, while the largest unevenness is found when the anionic diacetylene 1a is alternatingly adsorbed with the cationic bolaamphiphile 3 followed by subsequent UV polymerization on the substrate.