Polymer Ultra-Thin Film

The conformation of polymer chains in an ultra-thin film has been an attractive subject in the field of polymer physics. The chain conformation has been extensively discussed theoretically and experimentally [6-11] however, the experimental technique to study an ultra-thin film is limited because it is difficult to obtain a signal from a specimen due to the low sample volume. The conformation of polymer chains in an ultra-thin film has been examined by small angle neutron scattering (SANS), and contradictory results have been reported. With decreasing film thickness, the radius of gyration, Rg, parallel to the film plane increases when the thickness is less than the unperturbed chain dimension in the bulk state [12-14]. On the other hand, Jones et al. reported that a polystyrene chain in an ultra-thin film takes a Gaussian conformation with a similar in-plane Rg to that in the bulk state [15, 16]. 

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Conducting polymer ultra-thin films with monomolecular thickness (mono-layers) having the minimum dimension and of built-up multilayers with anisotropic structures were constructed. The properties from the monolayers and the evaluation of functions of these films were investigated. The... 

Ultra-thin films of polyanilinc may be spin-coaled onto the ITO substrates. By studying thick films, spectra of the polymer itself are obtained. As the thickness of the polymer overlayer is reduced, some of the subtle details of the interface between the very thinnest possible polymer layer (essentially a mono-layer, in the... 

For the investigation of polymer systems under spatial confinement, fluorescence microscopy is a powerful method providing valuable information with high sensitivity. A fluorescence microscopy technique with nanometric spatial resolution and nanosecond temporal resolution has been developed, and was used to study the structure and dynamics of polymer chains under spatial confinement a polymer chain in an ultra-thin film and a chain grafted on a solid substrate. Studies on the conformation of the single polymer chain in a thin film and the local segmental motion of the graft polymer chain are described herein. 

Figure 4.4 Histogram of the lateral chain dimension for the PMMA-Pe chains in ultra-thin films with thickness 15, 50, and 80 nm.The PMMAchains with a molecularweightof4 x 10 were selected in the SNOM images and analyzed to construct the histogram. Reproduced with permission from The Society of Polymer Science, Japan.

Aoki, H., Morita, S., Sekine, R. and Ito, S. (2008) Conformation of single poly(methyl methacrylate) chains in ultra-thin film studied by scanning near-field optical microscopy. Polym. J 40, 274-280. 

Plasma surface treatment of many polymers, including fabrics, plastics, and composites, often occurs. The production of ultra-thin films via plasma deposition is important in microelectronics, biomaterials, corrosion protection, permeation control, and for adhesion control. Plasma coatings are often on the order of 1 100 nm thick. 

Thin polymer films have many possible technical applications. Transistors and light-emitting diodes are the obvious ones. In ultra-thin films, one may even approach an electronics of molecular dimension. Molecular electronics will be a future challenge for basic and applied science. Nature applies it on a large scale in the reaction centers of the photosynthetic process, where photoinduced mobile charges are separated in some analogy to the separation of the photo-(p-n)-pair in the junction zone of a semiconductor (see Section 13.3.1). 

The samples studied in connection with work discussed here consist of ultra-thin films of molecular solids, either polymers or condensed molecular solids. It is useful, however, to describe first the molecular photoelectron emission process, at least from a phenomenological view point, and then present the extra issues in dealing with solids. 

In chapter 7, all works discussed on model molecular systems for conjugated polymers refer to condensed molecular solid ultra-thin films, generally prepared by condensation of molecules from the effusion of a Knudsen-type cell, in UHV, on to clean metallic substrates held at low temperatures. Clean is defined as atomically clean as determined by core-electron level XPS, such that there is intimate contact between the molecules at the substrate-film interface, without the influence of, for example, a metallic oxide, hydrocarbon... 

We focus on periodic systems (ID ordered polymers, 2D slabs and ultra-thin films, 3D —> crystals). A considerable variety of DFT implementations exists in codes for such systems, depending on the choice of basis set. (Somewhat confusingly for begiimers, in solid-state physics the choice of a basis commonly has been called a method , presumably because special techniques evolved to exploit the advantages and minimize the difficulties of each choice.) With few exceptions, modem codes are based on some approximate eigenvalue problem for an effective Hamiltonian, hence they expand the eigensolutions in linear combinations of one of four types of basis functions ... 

The vectors k are 3D, 2D, or ID for a crystal, slab, or periodic polymer respectively. Keep in mind that the nomenclature nD refers to the number of cartesian directions in which nuclei have periodic ordering. The electron density is three-dimensional, as is r, whatever the system periodicity. Thus, when we treat an ultra-thin film (UTF) with GTOFF, we are not doing a super-cell calculation on a fictitious crystal consisting of the UTF interspersed by layers of vacuum . GTOFF can do such super-cell calculations but more importantly, it can handle the UTF as a fi ee-standing object periodic in two Cartesian directions and of finite thickness in the third direction (conventionally z), subject to vacuum boundary conditions in z. Note also that a 2D GTOFF calculation does not require inversion s)mimetry with respect to z, hence can treat an even number of nuclear planes as readily as an odd number. 

However, ultra-thin films of unsubstituted polyaniline deposited on ITO glass electrode produced by dip coating, spin coating and the LB technique showed the most informative voltammetric characteristics. The single-layer LB films of polymer showed much better and reversible electrochromic activity on repeated scanning within up to 0,9 V in 1,0 M HCl solution than in electrochemically prepared materials [287],... 

Paddeu S., Ram M. K., and Nicolini C., Investigation of ultra-thin films poly (ortho)-anisidine conducting polymer obtained by the Langmuir-Blodgett technique J. Phys. Chem. B., 101, 4759-4766, 1997. 

J. Stumpe, Polymer Interfaces and Ultra-thin Films Characterized by Optical Evanescent Wave Techniques, Makromoleku-lare Chemie-Macromolecular Symposia 48/49, 363 (1991)... 

ULTRA-THIN FILMS OF TRICOSANOYL AND PENTACOSANOYL-10 12-DIYNOIC ACIDS AND THE RESULTANT POLYMERS... 

Standing of polymer crystallization in quasi-two dimensions. Simultaneously performed experiments on ultra-thin films (monolayers) of rather short polymers, obtained by autophobic dewetting in thin PEO or PS-PEO(3-3) films [36-38], will be presented subsequently. 

R. Silva, E.C. Muniz, A.F. Rubira, Multiple hydrophilic polymer ultra-thin layers covalently anchored to polyethylene films. Polymer 49, 4066 075 (2008)... 

The resistance to thermo-oxidation of the composite particles is much higher than that of the reduced iron particles due to the protection of ultra-thin polymeric film outside the iron powder. Also, the polymer encapsulation with the ultra-thin film enhances the resistance to acidic corrosion of the reduced iron particles. 

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