Abstract: Molecular orientation and phase transition behavior in the multilayer Langmuir-Blodgett(LB) film of reversed duckweed polymer ES-3 were investigated by infrared grazing reflection-absorption(IR-GRA) spectroscopy. It was found that the orientation of alkyl chains was nearly perpendicular to the substrate surface for ES-3 LB film on Au-evaperated glass slide. The study on its thermal transition behavior indicates that ES-3 LB film has three phase transition processes,occurring near 65, 105 and 140 ℃, respectively. The first transition corresponds to a conversion from a highly ordered state to the slightly less ordered one with a little increase in the mobility of alkyl chains; the second process is attributable to the order-disorder transition of alkyl chains; and the third is a process of collapse of layer structure.

Key words: Reversed duckweed, LB film, Phase transition, Grazing reflection-absorption infrared spectroscopy