VISCOELASTIC PROPERTIES AND COLLAPSE BEHAVIOR OF A SMECTIC LIQUID-CRYSTALLINE POLYMER AT THE AIR-WATER-INTERFACE

The viscoelastic behavior of a monolayer of a liquid-crystalline side-chain polymer in its collapse region is discussed. The material shows a reversible collapse with a strong temperature and compression speed dependence. The collapse process can be empirically described as a viscoelastic relaxation with two relaxation times. Because of this behavior, the importance of the ''time of observation'' is pointed out. A second increase of the surface pressure at lower mean molecular area and stepwise increases of the collapse viscosity are associated with the formation of bi- and trilayers. Reflectivity measurements with a Brewster angle microscope are used to confirm that the collapse is a homogeneous process, leading to multilayers with liquid crystalline properties at the air/water interface.