Amphiphilic diacetylenes with pyridine and 2,2′-bipyridine headgroups — polymerization properties in the crystalline state, in LB-multilayers, and in complexes with transition metal salts. Morphology of polymerized multilayers

Abstract

Synthesis, amphiphilic properties and polymerization behaviour of a variety of single and double chain esters of pyridine- and 2,2′-bipyridine-carboxylic acids containing the diacetylene moiety are described. Conversion versus⁶⁰Co-γ-ray dose curves indicate significant differences in solid-state reactivity of the individual compounds. The esters of isonicotinic acid form polymers that are soluble in chloroform. The monomers can be converted into salt derivatives and transition metal complexes, some of which are characterized concerning their solid state reactivity.

Esters of isonicotinic acid form stable monolayers if spread onto neutral or acidified aqueous subphases at temperatures ≤ 15 °C. These monolayers can be deposited on substrates by the Langmuir-Blodgett technique and subsequently be UV-polymerized. In addition, attempts are reported to form polymeric mono- and multilayers by spreading the soluble polymeric amphiphiles at the air-water interface and subsequently transferring the films onto substrates.

The two types of polymeric films exhibit morphologies that are significantly different. Polarizing micrographs indicate a domain structure of randomly shaped crystallites of only a few micrometers in diameter for LB-monolayers built up as monomers and polymerized on the substrate. On the other hand, polymer films built up as polymers are inhomogeneous and do not actually represent monomolecular films.