Polymerization of Langmuir-Blodgett films. A comparison of two different methods

We have formed Langmuir-Blodgett (LB) multilayers of a poly 6 (imidazolium) salts both by polymerizing the compound at the air/water interface and by spreading pre-formed polymers of the material. Low angle X-ray studies showed the multilayers formed by the first technique had a repeat distance of 3.75 nm whereas multilayers formed by the latter technique had a repeat distance of 3.96 nm and were less well ordered. Cast films of the pre-formed polymers also had a repeat distance of approximately 3.95 nm. Pre-formed polymers would only deposit as LB films after the initial compression. Subsequent expansion and compression produced monolayers at the air/water interface which would not form LB films. We believe that this particular phenomenon is unique. (C) 2001 Elsevier Science B.V. All rights reserved.