M. Mabuchi et al., Nanostructure and thermal stability of the polyglutamate Langmuir-Blodgettfilms probed by interlayer energy transfer method, MACROMOLEC, 31(25), 1998, pp. 8802-8808
Ultrathin films of alpha-helical polyglutamate with long flexible side chai
ns (PG) were fabricated by the LB technique, and their nanostructure was in
vestigated by the energy transfer method. The rodlike main chain of PG was
labeled by incorporating either energy donor (naphthalene, Np) or acceptor
(anthracene, An) molecules via short side chains. The fluorescence spectra
of Np-An multilayers with the same number of spacing layers gave different
energy transfer efficiencies, depending on the mode of depositions. This ph
enomenon was interpreted as being caused by the noncentered structure of th
e polymer backbone, which was probed by both X-ray reflectometry and fluore
scence spectroscopy. The Y-type deposition induced a bilayer structure in w
hich the stiff main chains of each monolayer were located close to the cent
er of the bilayer. The layered structures showed excellent thermal stabilit
y up to around 120 degrees C; By thermal treatment higher than 120 degrees
C, the layered structure relaxed to a stable state in which the alpha-helic
al backbones in each layer became intermingled.