FABRICATION OF ALTERNATING MULTILAYERS OF A DIACETYLENE GROUP CONTAINING AMPHIPHILIC LIGAND AND ACID, USING THE LANGMUIR-BLODGETT TECHNIQUE

The structure of alternating multilayers of two diacetylene group cont aining amphiphiles (an acid (A) and a pyridine ligand (B)), built up f rom a 5 mM CdBr2 subphase, is examined. SAXR measurements revealed tha t these multilayers have a regular layer structure with a bilayer spac ing of 55.2 Angstrom. From this bilayer spacing in combination with FT -IR measurements, it can be concluded that the aliphatic tails of amph iphile A have a tilt angle (ct) of about 34 degrees with respect to th e surface normal, while in the case of amphiphile B, alpha has a value of about 45 degrees. In the all-trans aliphatic alkyl chains of both amphiphiles, the C-C-C plane has a preferred orientation such that the symmetric stretches of the methylene groups of the aliphatic chain mu st be close to being in a plane parallel to the substrate. These multi layers can be partly polymerized by means of UV irradiation, forming t he red form (lambda(max) = 540 nm) of the polymer. Upon polymerization the regular layer structure is preserved and the bilayer spacing incr eases from 55.2 up to 57.9 Angstrom. The preferred orientation of the C-C-C plane of the aliphatic tail chain around the chain director is l ost during the polymerization process. Also, the all-trans alkyl chain is partly converted in a more irregular one containing gauche conform ations.