Reversible collapse of the Langmuir films of a series of triphenylsilyl ether-terminated amphiphiles

The Langmuir films of a series of triphenylsilyl ether (TPSE)-terminated amphiphiles were investigated in order to explore the bulge amphiphile model developed by Haycraft et al. [Thin Solid Films, 515 (2007) 2990]. The TPSE series was examined using surface pressure–surface area isotherms over a range of temperatures (287–298 K) with simultaneous acquisition of Brewster angle microscopy images. The Langmuir films of the TPSE series exhibit the reversible collapse process characteristic of bulge amphiphiles, including an observation consistent with the reversed cybotactic cluster model and increased entropy upon collapse. No solid-like monolayer phases were found over the temperature range studied. The reversed cybotactic clusters displayed for these films show domain growth and coalescence that differ from those observed by Haycraft et al.