Langmuir and Langmuir-Blodgett films of side-chain liquid-crystalline poly(maleic acid-alt-1-alkene)s

Langmuir layers of side-chain liquid-crystalline poly(maleic acid-alt-1-alkene)s(SCLCPs) with biphenyl mesogens were studied on water subphases but were also transferred by the use of the Langmuir-Blodgett technique. Brewster angle microscopy showed that the SCLCPs with methoxybiphenyl mesogens strongly aggregate on the water subphase and form islands, which merge upon compression. In contrast, SCLCPs with cyanobiphenyl mesogens spread nicely and compression of these polymers resulted in the formation of triple layers. Langmuir monolayers of SCLCPs with methoxybiphenyl mesogens show Z-type transfer. Atomic force microscopy and X-ray reflectivity measurements of the resulting Langmuir-Blodgett mono and/or multilayers indicate that the side chains of these polymers are possibly tilted. The multilayers have a double layer periodicity, which requires a reorientation of the side chains during or after transfer. Annealing of these Langmuir-Blodgett films resulted in an increase of the mean film thickness and a more uniform d spacing within the multilayer. With atomic force microscopy droplets were observed on top of the multilayer, indicating dewetting of the upper layers.