A water-soluble polysilane having a trimethylammonium group has been synthesized and its spectroscopic properties in water, ethanol and their binary mixtures are investigated. In water-ethanol binary mixtures, variations in the UV absorption and fluorescence properties attributed to the delocalized σ electron in the Si backbone exhibit a maximum at intermediate mixing ratios.
Poly(dihexylsilane) (PDHS) and arachidic acid (AA) were co-spread onto a cadmium-containing water subphase and transferred onto a solid substrate as multilayers by the Langmuir-Blodgett method. The structure of these films was evaluated by means of UV-visible absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry, and film thickness measurements. The results indicated that the PDHS ultrathin film is incorporated into a well-structured AA multilayer matrix without appreciable destruction of the layer structure. The conformational behavior of PDHS embedded within this film was evaluated by UV-visible absorption spectroscopy. The phase transition temperature of the ordered (alltrans zigzag) to the disordered (helical gauche) state on the AA monolayer at the air-water interface is lowered and the conformational state is virtually maintained in the as-deposited multilayers during storage at room temperature at least for a month. PDHS in the AA multilayer on heating showed a substantially broadened transition around 40 8C, which clearly reflects a geometrical restriction effected by the AA multilayer matrix.
Langmuir-Blodgett (LB) films of a water solu ble cationic polysilane are successfully prepared by ion-complexation with an arachidic acid monolayer at the air-water interface; UV absorption characteristics of the LB films are dependent on the pH of the water subphase on transfer.
Monolayers of anionic amphiphiles, arachidic acid
(C19COOH) and a double long chain
sulfonic acid derivative (2C12SO3Na),
were spread on the water subphase containing an ammonium-containing polysilane (APS), and Langmuir−Blodgett (LB) films from
these polyion complex monolayers
were prepared. Single layer deposition of these polyion complex
monolayers was successfully achieved
onto a hydrophilic substrate under all conditions examined, but
multilayers could be prepared under
limited conditions in the Z-type mode. The UV absorption spectra
of the transferred C19COO(H)/APS
monolayers indicated that the conformational state of APS in the films
are dependent on the subphase
pH. The absorbance of the transferred LB films confirmed that the
APS is incorporated monomolecularly
on the lifting process. Polarized UV absorption spectra revealed
no preferential orientation of the APS
backbone in the LB films. The multilayers formed in the Z-type
deposition were eventually inverted to
stacked bilayer structure (Y-type layers) after aging and successive
annealing, as proven by the small
angle X-ray reflectometry. LB films composed of
2C12SO3
-/APS possessed a
more refined layer structure
with a more smooth surface than those of
C19COO(H)/APS, probably due to a better
dimensional matching
of the APS unit and the cross section of the amphiphile. Finally,
structural features of the C19COO(H)/APS polyion complex LB film were discussed in comparison with those of a
homologous amphiphilic
material reported previously (Seki et al. Macromolecules
1995, 28, 5609).
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