DEVELOPMENT OF A TEMPERATURE PROGRAMMABLE LANGMUIR TROUGH AND MEASUREMENTS OF A-T ISOBARS OF MYRISTIC ACID MONOLAYERS

A temperature programmable Langmuir trough using a large number of Peltier elements has been developed. Surface temperature of the subphase water in the trough can be changed at a maximum rate of 8-degrees-C/min linearly with time in both heating and cooling. Fluctuation of the surface temperature was within +/- 0.02-degrees-C at a constant temperature control. heating-rate dependence and surface-pressure dependence of A-T isobars of myristic acid monolayers at the air/water interface were measured with this instrument. The first-order phase transition from liquid-condensed to liquid-expanded state of monolayers considerably depended on the heating rate. The transition temperature also depended on the surface pressure. This trough will be especially useful for making defect-free LB films by the "isobaric thermal treatment" of monolayers.