Blodgett Films Of Poly Research Articles

Langmuir–Blodgett films of poly(phenylacetylene) derivatives

LB films of poly(alkoxyphenyl)acetylenes were fabricated, and the higher order structure in the bidimensional field was examined. The polymers formed monolayer films on water surface, though these polymers have no hydrophilic group. For the preparation of the multilayer LB film the horizontal lifting method was more effective than the vertical dipping. The type of substituent affected the aggregated structure and orientation of the film. Area per monomer unit decreased when a chiral alkoxyl group was introduced into para-position. The LB films for the meta-substituted polymer showed some anisotropy in the polarized ultraviolet visible absorption spectrum, indicating that in-plane orientation was induced by compression. The absorbance observed in the perpendicular to direction of compression was stronger than that of parallel one.

Langmuir−Blodgett Films of Poly(3-hexylthiophene) Doped with the Endohedral Metallofullerene Dy@C82: Preparation, Characterization, and Application in Photoelectrochemical Cells

We have successfully constructed photoelectrochemical (PEC) cells based on the Langmuir−Blodgett (LB) films of poly(3-hexylthiophene) (P3HT) doped with Dy@C82. The composite structure is featured by the interaction between Dy@C82 and the thiophene building blocks of P3HT, which take an edge-on arrangement at the air/water interface. The usage of the P3HT−Dy@C82 composite LB films in photoelectrochemical (PEC) cells yields a dramatic enhancement of the cathodic photocurrent, with the power-conversion efficiency (ηe) and quantum yield (Φ) being up to 16-fold and 9-fold higher, respectively, than those of pure P3HT cells. This is attributed to the facile photoinduced electron transfer between P3HT and Dy@C82, which is also revealed by photoluminescence (PL) spectroscopic characterization. The optimum PEC performance is found to be correlated with an ordered film structure as revealed by AFM measurements. The effects of the electron acceptor, bias voltage, light intensity, and number of layers have been studied in detail. Comparison studies have also been conducted with bilayer PEC cells and PEC cells in which Dy@C82 is replaced by C60. A possible mechanism for the cathodic photocurrent generation is proposed on the basis of these studies.

Structure and Characterization of Nanocomposite Langmuir−Blodgett Films of Poly(maleic monoester)/Fe3O4 Nanoparticle Complexes

Nanocomposite Langmuir−Blodgett films of poly(maleic monoester) (PMA)/Fe3O4 nanoparticles were prepared by transferring PMA/iron oxide nanoparticles complex monolayers in a hydrosol subphase of Fe3O4 nanoparticles onto solid substrates. A Mossbauer spectrum of the nanoparticles showed the highly crystalline nature of the magnetite structure. Homogeneous dispersion of Fe3O4 nanoparticles between poly(maleic monoester) layers was observed with transmission electron microscopy (TEM), and surface morphology of the nanocomposite film was studied with atomic force microscopy (AFM). The magnetic properties of the Fe3O4 nanoparticles and the nanocomposite Langmuir−Blodgett film of poly(maleic monoester) (PMA)/Fe3O4 nanoparticles were studied with vibrating magnetometry (VSM) by obtaining magnetic hysteresis loops. The PMA is a polymeric surfactant and interacts with Fe3O4 nanoparticles by electrostatic attraction between carboxylate groups of PMA and the charged Fe3O4 nanoparticles. This interaction stabilizes th...

A Grazing Incidence X-ray Diffraction Study of Langmuir−Blodgett Films of Poly(vinylpyridine) Quaternized with n-Docosyl Bromide

The in-plane order of Langmuir−Blodgett multilayers of a poly(4-vinylpyridine) quaternized with n-docosyl bromide has been studied by grazing incidence X-ray diffraction. Strong evidence has been found for interactions of the alkyl side chains of the polymer molecules in neighboring layers, and an in-plane packing structure has been derived. Quantitative analysis of the X-ray diffraction shows that strain disorder rather than domain size is the principal source of X-ray line broadening in this system.

Structural Relaxation of Langmuir−Blodgett Films of Poly(vinyl octanal acetal) with Various Tacticities

Poly(vinyl octanal acetal) (PVO) was prepared from poly(vinyl alcohol) (PVA) in which the main chain had three different tacticities and the stereoregularity was characterized by 1H NMR spectroscopy. a-PVO prepared from atactic-PVA and s-PVO from syndiotactic-PVA had similar fractions of cis- and trans-acetals in the main chain, but i-PVO from isotactic-PVA had different ones. Ultrathin films of these polymers were prepared by the Langmuir−Blodgett (LB) technique, and the thermal relaxation of their multilayer structure was investigated by the energy-transfer method. When the LB films were composed of polymers which had a main chain with a similar stereostructure, the polymers were intermingled with each other by the thermal treatment and the onset of the diffusion of polymer segments was affected by the glass-transition temperature of the bulk. In contrast, the polymers with different stereostructures in each layer were not mixed with each other, but phase-separated, presumably forming droplets in the ultrathin films. It is concluded that the relaxation behavior of polymer LB films strongly reflects the stereoregularity of the sample polymers.