scholarly journals Growth and Switching of Ferroelectric Nanocrystals from Ultrathin Film of Copolymer of Vinylidene Fluoride and Trifluoroethylene

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
R. Gaynutdinov ◽  
V. Fridkin ◽  
H. Kliem
Keyword(s):  
Self Assembly ◽  
Vinylidene Fluoride ◽  
Paraelectric Phase ◽  
Orthorhombic Space Group ◽  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Storage Media ◽  
Atomic Force ◽  
Kinetics Of

The ferroelectric nanocrystals of the copolymer of vinylidene fluoride and trifluoroethylene P(VDF-TrFE) were grown from ultrathin Langmuir-Blodgett (LB) films on Si substrate. The annealing of ultrathin LB films with thickness of 3 monolayers (5 nm) in air in paraelectric phase at temperature 125∘C was performed. The self-assembly leads to the growth of nanocrystals of ferroelectric copolymer 15–25 nm thick and 100–200 nm in diameter. The nanocrystals presumably belong to orthorhombic space group, where axis 2 is the direction of spontaneous polarization (and normal to substrate). By means of atomic force microscopy (AFM), the kinetics of ferroelectric nanocrystals growth and their switching were investigated. The obtained results confirm the conclusions that copolymer nanocrystals are candidates for high-density nonvolatile storage media devices.

Structural and Morphological Characterization of Ultrathin Films of an Asymmetric Polydiacetylene

1996 ◽  
Vol 440 ◽  
Author(s):  
H. C. Wang ◽  
D. W. Cheong ◽  
J. Kumar ◽  
C. Sung ◽  
S. K. Tripathy
Keyword(s):  
Second Harmonic ◽  
Morphological Characterization ◽  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Glass Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Air Water Interface

AbstractA soluble, asymmetrically substituted polydiacetylene, poly(BPOD), has been reported to form stable monolayers at the air-water interface by the Langmuir-Blodgett (LB) technique [2]. Preformed polydiacetylene has been deposited onto hydrophobic substrates as multilayers to form second order nonlinear optical thin films. Second harmonic generation was found to increase with the number of layers. From previous atomic force microscopy (AFM) studies backbone orientation along the dipping direction with an interchain spacing of about 5 A° was indicated [2].The film morphology and preferential molecular orientation of these LB films are further investigated by transmission electron microscopy (TEM). A specifically tailored sample preparation method for the ultrathin LB films was used. Multilayer films were deposited on hydrophobic collodion covered glass substrates for this purpose. Electron diffraction was employed to study the crystalline organization of mono and multilayers of LB films as well as cast films.

scholarly journals Self-Assembly of Rice Bran Globulin Fibrils in Electrostatic Screening: Nanostructure and Gels

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Lihua Huang ◽  
Yehui Zhang ◽  
Haibin Li
Keyword(s):  
Ionic Strength ◽  
Rice Bran ◽  
Self Assembly ◽  
Gel Properties ◽  
Sem Images ◽  
Force Microscopy ◽  
Atomic Force ◽  
Repulsive Forces ◽  
Low Ionic Strength ◽  
Kinetics Of

The effects of various ionic strengths and protein concentrations on the fibrils structure and gel properties of rice bran globulin (RBG) at pH 2.0 were investigated using atomic force microscopy (AFM), rheometer, and scanning electron microscope (SEM). AFM images showed the morphology of assembling RBG fibrils from strand beads to becoming branch clustered, when electrostatic repulsive forces attenuated gradually with increasing ionic strength. NaCl seems to accelerate the kinetics of fibrils formation, resulting in a significant increase in Th T fluorescence intensity. The increased ionic strengths promote particle size increasing and zeta potential decreasing synchronously. The percolation modelG'~C-Cpnbe used to calculate theoretical RBG gels concentration at various ionic strengths (0–500 mM), which decreased from 15.17 ± 0.63 to 2.26 ± 0.27 wt%. SEM images exhibited a granular mesh-like gel structure. A more homogenous structure occurred in low ionic strength. This study elucidates properties of RBG fibrils and gels as a bioactive material.

Atomic Force Microscopy (AFM) Investigation of Langmuir-Blodgett (LB) Films of Sugar Cane Bagasse Lignin

Holzforschung ◽  
2000 ◽  
Vol 54 (1) ◽  
pp. 55-60 ◽  
Author(s):  
C. J. L. Constantino ◽  
A. Dhanabalan ◽  
M. A. Cotta ◽  
M. A. Pereira-da-Silva ◽  
A. A. S. Curvelo ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sugar Cane ◽  
Sugar Cane Bagasse ◽  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Domain Structures ◽  
Atomic Force ◽  
Poor Stability ◽  
Cadmium Stearate

Summary The morphological features of Langmuir-Blodgett (LB) films of pure lignin extracted from sugar cane bagasse and composites of lignin and cadmium stearate have been investigated using atomic force microscopy (AFM). Results indicated that despite the non-amphiphilic nature of lignin and associated relatively poor stability and transferability of the lignin monolayer, the surface of the film is smooth at the micron level and comparable to that of LB films from typical amphiphilic compounds. Distinct domain structures from lignin and cadmium stearate could be visualized in the composite LB film even in one monolayer thick LB films. The mean surface roughness increases with increasing numbers of layers.

Langmuir-Blodgett Films of Calcium Stearate

1994 ◽  
Vol 351 ◽  
Author(s):  
Necesio Costa ◽  
Mark Aindow ◽  
Peter M. Marquis
Keyword(s):  
Film Surface ◽  
Organic Matrix ◽  
Calcium Stearate ◽  
Contact Mode ◽  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Atomic Force ◽  
A Value ◽  
Langmuir Blodgett Films

ABSTRACTThe Langmuir Blodgett (LB) Process has been shown to be an appropriate method for use in mimicking of biological processes for producing engineering materials such as bioceramics. The main advantages of this approach are that the layers form at low temperatures, that they are fully dense and that the process of densification is by infiltration rather than by sintering. Moreover, biological hard tissues are self-assembled to perform certain functions; the architecture being controlled by an epitaxial organic matrix. Clearly, if this process can be understood in detail then it is possible that LB films may be used to replicate this architecture for engineering purposes.Atomic Force Microscopy (AFM) and X-ray diffraction (XRD) have been used to study and characterise LB films of calcium stearate obtained by the repeated dipping into and withdrawal of a (001) Si wafer from a subphase containing calcium ions and using stearic acid as the surfactant. Contact-mode AFM images of the film surface have been used to measure the thickness of the LB layers and to reveal the nature and distribution of defects in the film. The measured thickness of the calcium stearate layers is about 2.5 nm; a value consistent with that obtained by XRD, but smaller than the length of an individual calcium stearate molecules.

Optical changes induced in Zn porphyrin solutions and LB films by exposure to amines

2006 ◽  
Vol 10 (07) ◽  
pp. 978-985 ◽  
Author(s):  
Alan D. F. Dunbar ◽  
Tim H. Richardson ◽  
Alex J. McNaughton ◽  
Ashley Cadby ◽  
Jordan Hutchinson ◽  
...  
Keyword(s):  
Near Field ◽  
Chloroform Solution ◽  
Electron System ◽  
Visible Range ◽  
Material System ◽  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Atomic Force ◽  
Good Material

The 5,10,15,20-tetrakis[3,4-bis(2-ethylhexyloxy)phenyl]-21 H ,23 H -porphinato zinc(II) ( ZnEHO ) is highly stable and exhibits a colorful absorption spectrum in the visible range. Exposure of a chloroform solution of ZnEHO to amines is shown to induce changes in the characteristic optical spectrum owing to charge transfer between the amine and the delocalized π-electron system within the highly conjugated molecule. Solid state Langmuir Blodgett (LB) films containing only ZnEHO are compared to films containing a mixture of ZnEHO and calix[8]arene. The transparent calix[8]arene does not change the optical response but aids the diffusion of the amine gas into the LB films. Atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) images demonstrate the topological and compositional differences between the samples. The response of the LB films of ZnEHO and calix[8]arene to a variety of different amines demonstrates that this is a good material system for use as an amine sensor.

THE KINETICS OF THE AS GROWN AND ANNEALED SELF-ASSEMBLED MONOLAYER STUDIED BY FORCE SPECTROSCOPY

2018 ◽  
Vol 25 (02) ◽  
pp. 1850054
Author(s):  
HUMA HABIB ◽  
M. YASAR ◽  
S. MEHMOOD ◽  
SAIMA RAFIQUE ◽  
A. S. BHATTI ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Self Assembly ◽  
Surface Coverage ◽  
Work Of Adhesion ◽  
Self Assembled Monolayer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Alkane Thiol ◽  
Self Assembled ◽  
Kinetics Of

The growth of biological systems like DNA, peptides and proteins are accredited to the self-assembly processes from the molecular level to the nanoscale. The flawless immobilization of DNA on any surface is quite an important step to the development of DNA-based biosensors. The present paper reports the use of atomic force microscopy to determine the mechanical properties of the as grown and annealed self-assembled monolayer (SAM) as well as the mutated DNA immobilized on the SAM. The SAM of alkane thiol (16-mercapto-1-hexadecanol) was developed on Au surface, which was then annealed and analyzed for its structural and mechanical properties. The surface coverage, height and monolayer’s order was studied as a function of incubation time and annealing time. Excessive annealing led to the defragmentation and desorption of SAM structures due to breaking of hydrocarbon bonds. AFM was employed to determine the detach separation, pull-off and work of adhesion of the as grown and annealed SAM.

A STUDY ON THE LANGMUIR–BLODGETT (LB) FILMS OF C60/POLY (N-VINYLCARBAZOLE) (PVK) POLYMERS

2006 ◽  
Vol 20 (13) ◽  
pp. 753-760 ◽  
Author(s):  
XIAOHONG JIANG ◽  
XINGTANG ZHANG ◽  
YABIN HUANG ◽  
ZULIANG DU
Keyword(s):  
Arachidic Acid ◽  
Composite Films ◽  
Deposition Method ◽  
Hybrid Films ◽  
Lb Films ◽  
Vertical Deposition ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Atomic Force ◽  
Vertical Deposition Method

The Langmuir–Blodgett (LB) films of Poly (N-vinylcarbazole) (PVK) Polymers and its hybrid films with arachidic acid (AA) and C 60 were prepared by a vertical deposition method. Atomic Force Microscopy (AFM) and UV-Vis absorption spectroscopy were used to investigate the assembly of PVK/AA and PVK/ C 60/AA LB films. It was found that the C 60 molecules could be aggregated into smaller particles on the base of PVK polymers. The photoluminescence (PL) of PVK was dramatically quenched resulting from the electron transfer from PVK to C 60 in their composite films.

Nanostructured LB Films Developed from Ferrocenylthioamide and Ferrocenylselenoamide Compounds

2014 ◽  
Vol 1613 ◽  
pp. 67-72
Author(s):  
Rosa E. Lazo-Jiménez ◽  
María C. Ortega-Alfaro ◽  
José G. López- Cortés ◽  
José A. Chávez-Carvayar ◽  
Jordi Ignés-Mullol ◽  
...  
Keyword(s):  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Glass Substrates ◽  
Molecular Monolayers ◽  
Atomic Force ◽  
Pharmacological Interest ◽  
Air Water Interface ◽  
Conjugated Compounds ◽  
Donor Moiety

ABSTRACTIn this work, the synthesis of two amphiphilic π-conjugated compounds such as ferrocenylthioamide and ferrocenylselenoamide, with the general formula FcC=MNH(CH2)15CH3 with M = S or Se, are reported. The ferrocenyl group is a donor moiety forming a π-conjugated system with the amides of sulfur and selenium; both elements have also bioactivity with pharmacological interest. These two compounds formed Langmuir (L) monolayers at the air-water interface, which were characterized by isotherms of surface pressure versus molecular area (π-A) and compression/expansion cycles (hysteresis curves); Brewster angle microscopic images were also obtained. By using the Langmuir-Blodgett method molecular monolayers were transferred onto glass substrates. These nanostructures, in form of Langmuir-Blodgett (LB) films, were characterized through atomic force microscopy (AFM).

Langmuir-Blodgett Film Stability Via Atomic Force Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 306-307
Author(s):  
Dawn Y. Takamoto
Keyword(s):  
Fatty Acid ◽  
Monolayer Film ◽  
Fatty Acid Salt ◽  
Film Stability ◽  
Blodgett Film ◽  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Atomic Force ◽  
Langmuir Blodgett Film

Langmuir-Blodgett (LB) films of fatty acid salts are inherently unstable due to the fundamental incompatibility of the asymmetric monolayer film transferred from the water surface with the centrosymmetric equilibrium form of the fatty acid bulk crystal. One consequence of this incompatibility is that fatty acid salt films deposited by the LB technique do not remain as flat and uniform films, but reorganize into bilayer step islands. By using mixed chain length films, the islands and holes had distinct heights that suggest this reorganization occurs by a bulk folding of the layers rather than a molecular reorganization of the molecules.We have studied cadmium arachidate (CdA) LB films, varying the substrate used, the number of layers deposited, and the time the film spends under the aqueous subphase. All films were imaged in air with an Atomic Force Microscope (AFM).

Dynamics of InAs Quantum Dots Formation on AlAs and GaAs

2000 ◽  
Vol 648 ◽  
Author(s):  
M. Yakimov ◽  
V. Tokranov ◽  
S. Oktyabrsky
Keyword(s):  
Quantum Dots ◽  
Self Assembly ◽  
Single Layer ◽  
High Energy ◽  
Ex Situ ◽  
Inas Quantum Dots ◽  
Force Microscopy ◽  
Atomic Force ◽  
Kinetics Of

AbstractWe have studied the formation of InAs quantum dots (QDs) grown by molecular beam epitaxy on top of GaAs and 2 ML-thick AlAs layers in the temperature range from 350 to 500°C. In-situ reflection high energy electron diffraction (RHEED) patterns were recorded in real time during the growth and analyzed to characterize the 2D-to-3D transition on the surface, including QD formation, and ripening process. The kinetics of QD formation was studied using the InAs growth rates ranging from 0.01 to 1 ML/s and different ratios of As2/In fluxes. RHEED patterns and ex-situ atomic force microscopy images were analyzed to reveal the development of sizes and shapes of the single-layer and stacked QD ensembles. The critical InAs coverage for QD formation was shown to be consistently higher for dots grown on the AlAs overlayer than for those grown on GaAs surface. Self-assembly of multilayer QD stacks revealed the reduction of the critical thickness for dots formed in the upper layers.

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