polymer thin-film

Top PDF polymer thin-film:

Chain end segregation at polymer thin film surfaces

Chain end segregation at polymer thin film surfaces

dPS-TFE and 6.3k PS-TFE blends, lower molecular weight end-functionalized additives may provide even higher surface coverage at low bulk concentrations,. useful from the sta[r]

97 En savoir plus

Antimicrobial Peptide Delivery from Degradable Polymer Thin Films

Antimicrobial Peptide Delivery from Degradable Polymer Thin Films

Staphylococcus aureus (MRSA). Treatment possibilities slowly become exhausted as bacteria gain further resistance to more potent drugs. Localized delivery rather than systemic delivery of novel drugs that do not cause bacterial resistance to arise is very desirable. Examples of such a class of therapeutics are antimicrobial peptides. These highly potent, broad spectrum peptides are part of the eukaryote innate immune system and display a wide range of activity against gram positive, gram negative, and drug resistant bacteria [1]. Layer-by-layer assembled thin films can be used to create a system capable of sustained delivery of therapeutic doses of antimicrobial peptides that can be administered locally. In this technique, the sequential adsorption of complementary charged polymer groups onto a charged substrate, leads to the electrostatically driven buildup of a polymer thin film [2]. Charged drugs (such as an antimicrobial peptide) containing layers can also be assembled in these architectures. Film
En savoir plus

3 En savoir plus

Influence of outer-layer finite-size effects on the dewetting dynamics of a thin polymer film embedded in an immiscible matrix

Influence of outer-layer finite-size effects on the dewetting dynamics of a thin polymer film embedded in an immiscible matrix

perhaps due to disjoining forces that become dominant at these length scales, 47 are often detrimental to the improved macro- scopic or material properties of the obtained material. 48 In order to study the physical phenomena responsible for such breakups and their subsequent dynamics, we recently developed a model experiment in which we observe the rupture of a polymer thin film within two thicker layers of another polymer, i.e. a symmetric liquid system with two polymerpolymer interfaces, instead of one polymerpolymer interface and one polymer–air interface in the case of a polymer bilayer on a rigid substrate. 49 This experiment consists of placing a thin (B100 nm) film within two thicker (\1 mm) layers spin- coated on glass slides. We studied the hole formation and growth over time (i.e. R = f (t) where R is the radius of the hole and t is the time) under a microscope while heating at a temperature similar to the extrusion temperature, well above T g . In this experiment, no external flow was applied. Though
En savoir plus

9 En savoir plus

Influence of outer-layer finite-size effects on the dewetting dynamics of a thin polymer film embedded in an immiscible matrix

Influence of outer-layer finite-size effects on the dewetting dynamics of a thin polymer film embedded in an immiscible matrix

perhaps due to disjoining forces that become dominant at these length scales, 47 are often detrimental to the improved macro- scopic or material properties of the obtained material. 48 In order to study the physical phenomena responsible for such breakups and their subsequent dynamics, we recently developed a model experiment in which we observe the rupture of a polymer thin film within two thicker layers of another polymer, i.e. a symmetric liquid system with two polymerpolymer interfaces, instead of one polymerpolymer interface and one polymer–air interface in the case of a polymer bilayer on a rigid substrate. 49 This experiment consists of placing a thin (B100 nm) film within two thicker (\1 mm) layers spin- coated on glass slides. We studied the hole formation and growth over time (i.e. R = f (t) where R is the radius of the hole and t is the time) under a microscope while heating at a temperature similar to the extrusion temperature, well above T g . In this experiment, no external flow was applied. Though
En savoir plus

9 En savoir plus

Flexible PZT thin film transferred on polymer substrate

Flexible PZT thin film transferred on polymer substrate

4. Conclusion A new process for PZT transfer to polymer substrate is described in this paper. The use of chemical solution deposition for the realization of the PZT on sacrificial substrate is complementary with chemical technics developed for the transfer process. The entire process is then easy to industrialize. Structural characterizations were realized to ensure the good binding between the different layers after the transfer. The crystallinity of the PZT was also checked before ferroelectric and dielectric measurements. Before and after transfer process, comparison was done for those electrical measurements revealing a small degradation of properties due to the etching step. The explanation proposed is that the PZT porosity is enhanced because of the interaction with iron chloride solution. Nevertheless, characteristics of PZT/PET composite are very interesting and this structure will be investigated for sensing and energy harvesting applications.
En savoir plus

19 En savoir plus

Hybrid solar cells based on thin-film silicon and P3HT

Hybrid solar cells based on thin-film silicon and P3HT

Fig. 3. Absorption spectra of layers in a device of type II. is part of the absorption range of P3HT. This partly ex- plains the low level of photocurrent when amorphous sil- icon is used as the intrinsic layer. Nevertheless, the re- spective absorption maxima of the polymer and silicon are clearly separated, so the devices should make an effi- cient use of the solar spectra when the silicon layer is thin enough. Moreover, amorphous silicon is used in most sam- ples because its higher bandgap allows to reach a higher

5 En savoir plus

Self-rolled polymeric thin film: toward fully functionalized microsystems

Self-rolled polymeric thin film: toward fully functionalized microsystems

Thin films of PDMS are either coated by a layer of hard material or have their surface hardened by plasma oxidation [3]. They are then driven out of equilibrium by selective solvent swelling resulting in a tubular rolled-up system (figure 1). We demonstrate topographical and chemical patterning, respectively by embossing and microcontact printing. In both cases, the pattern covers the whole surface of the tube, which typically cannot be obtained with standard techniques [4].

2 En savoir plus

Optimum Phase for Thin Film Synthesis by Fourier Transforms

Optimum Phase for Thin Film Synthesis by Fourier Transforms

OCIS codes: (310.0310) Thin films; (310.1620) Interference coatings; (310.6805) Theory and design; (310.5696) Refinement and synthesis methods Thin film synthesis techniques can generate solutions from much more elementary starting designs than conventional refinement. This is an appreciable advantage because the demands on filter performance increase continuously. One of the first practical synthesis approaches, proposed several decades ago but still of interest in particular for rugate filters, establishes an analytical relationship between a refractive index profile n(x) and its transmittance T(σ) through a Fourier transform [1,2]:
En savoir plus

4 En savoir plus

Bias-Stress Effect in Pentacene Organic Thin-Film Transistors

Bias-Stress Effect in Pentacene Organic Thin-Film Transistors

Vladimir Bulovi´c received the B.S.E. and Ph.D. degrees from Princeton University, Princeton, NJ, in 1991 and 1998, respectively. He is an Associate Professor of electrical engi- neering with the Massachusetts Institute of Tech- nology (MIT), Cambridge, leading the Organic and Nanostructured Electronics Laboratory, codirecting the MIT-ENI Solar Frontiers Center and the MIT Solar Revolutions Project, and leading the MIT Energy Studies Minor. He founded QD Vision, Inc., Watertown, MA, which is focused on development of quantum dot optolectronics, and Kateeva, Inc., Menlo Park, CA, which is focused on development of printed organic electronics. He is the author of 90 publications and the holder of 45 U.S. patents in the areas of organic and nanostructured light-emitting diodes, lasers, photovoltaics, photodetectors, chemical sensors, and programmable memories. His research interests include studies of physical properties of organic and organic/inorganic nanocrystal composite thin films and structures and the development of novel optoelectronic organic and hybrid nanoscale devices.
En savoir plus

7 En savoir plus

Microcrystalline silicon based thin film transistors fabricated on flexible substrate

Microcrystalline silicon based thin film transistors fabricated on flexible substrate

The glass will be flexible when its thickness reduced less than 200 μm [27]. Some commercialized thin glass‟s thickness can be reduced until 25 μm [28]. The main advantages of thin glass as flexible substrate include the quasi-perfect surface with roughness normally less than 0.5 nm, the high optical transparency, the high process temperature without thermal deformation, the impermeability of water or oxygen and the high chemical resistance. Benefiting from these properties, the TFTs or LCD and OLED can be fabricated on thin glass substrate with high performances. For example, S. M. Garner et al [29] present a high- quality and high-resolution electrophoretic display driven by organic TFT on flexible glass substrate. Benefit from the high quality of glass surface, the organic TFTs are electrically stable. S. Hoehla et al [30] use 75-µm-thick flexible glass for an active matrix LCD display. The TFTs have been directly fabricated on the glass substrate without degradation compared to the TFTs fabricated on thicker glass. On the other hand, the main drawback of thin glass substrate is its fragility and the high fabrication cost.
En savoir plus

163 En savoir plus

Carbon Nanotube Array Electrodes for Organic Thin Film Transistors

Carbon Nanotube Array Electrodes for Organic Thin Film Transistors

2.3.1 Vacuum-deposited organic semiconductors: the case of TiOPc The deposition of TiOPc was carried out at the Institute of Materials for Electronics and Magnetism (IMEM) part of the Italian National Research Council (Trento). Thin films of TiOPc were deposited using supersonic molecular beam epitaxy (SuMBE), a technique exploiting the kinetic properties of an expanded neutral gas, seeded with TiOPc molecules, forced to expand in an UHV (ultra-high-vacuum) chamber. After the supersonic expansion, a highly focused beam of TiOPc molecules with high kinetic energy (15 eV, to be compared with 0.2-0.5 eV in thermal evaporation) and narrow velocity distribution is obtained. The continuous free jet generated by the high-pressure seeded gas flows from a narrow nozzle into a vacuum chamber environment (Figure 2.8).
En savoir plus

117 En savoir plus

Elastic-strain distribution in metallic film-polymer substrate composites

Elastic-strain distribution in metallic film-polymer substrate composites

line nature, i.e., a mixture of crystalline and amorphous phases. Related peaks under synchrotron radiation 共E = 20 keV兲 are obtained at smaller 2 ␪ angles and stopped by the beamstop 共Fig. 1 兲. Figure 2 shows the x-ray intensity measured from both the coated and the bare polyimide sub- strates on synchrotron beamline. For the coated sample, we obtain an intense peak attributed to gold while another one appears at smaller 2 ␪ . Latter one is similar to that detected for the uncoated polyimide sample and is attributed to the substrate. Hence, using XRD we are able to monitor both film and substrate responses and extract respective strains fitting both peaks by Pearson VII functions. Changes in in- terplanar spacing d hkl can be used with Bragg’s law ␭
En savoir plus

4 En savoir plus

Femtosecond laser patterning of Ta0.1W0.9Ox/ITO thin film stack

Femtosecond laser patterning of Ta0.1W0.9Ox/ITO thin film stack

https://doi.org/10.1016/j.apsusc.2006.10.040 Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Femtosecond laser patterning of Ta0.1W0.9Ox/ITO thin film stack Lee, Seongkuk; Yang, Dongfang; Nikumb, Suwas

25 En savoir plus

Self-rolled polymer film: a route to microfluidic devices

Self-rolled polymer film: a route to microfluidic devices

We investigate the case of PDMS-based bilayer. The instability is driven by PDMS swelling in solvent vapors. The second layer – responsible of the inhomogeneity - can be another harder material. We present two different cases where i- the hard layer is another thin film polymer deposited on the pdms and ii- the hard layer is made by the oxidation of the pdms layer itself. This last case is of main interest since it is the way used for soft-lithography. In Figure 1, we report the inner diameter of self-rolled films as a function of the total bilayer thickness: tubes as small as 25µm are achieved.
En savoir plus

3 En savoir plus

SrxFeyOz-δ synthesis, structure and thin film gas sensing properties

SrxFeyOz-δ synthesis, structure and thin film gas sensing properties

Unlike other population balance processes, spray dynamic modeling is further complicated due to the existence of multiple cascaded physical mechanisms, such as primary lig[r]

9 En savoir plus

High performance thin film bulk acoustic resonator covered
with carbon nanotubes

High performance thin film bulk acoustic resonator covered with carbon nanotubes

Eq. 共12兲 in Ref. 16兴 is strongly dependent on the acoustic impedance of the electrodes. Basically, we have tuned these acoustic impedances via a CNT film deposition matching it in one point with that of the VNA generator. However, fur- ther simple quantitative considerations cannot be extracted easily based on a simple transmission line model. 16 Here, electromagnetic distributed effects such as standing waves along electrode surfaces are experimentally observed 共the ripples around resonant frequency in Figs. 3 and 4兲, while the electrical permittivity of GaN is quite low 共␧ r = 9.2 in the
En savoir plus

4 En savoir plus

Thin Film-Based Optically Variable Security Devices : From Passive to Active

Thin Film-Based Optically Variable Security Devices : From Passive to Active

thesis is shown in Figure 5.1. It is also important to note that of all the adjustable deposition parameters (gas ratios, gas flows, pressure, temperature, etc.), it is the deposition pressure and temperature as well as the energy and flux of impinging ions which have the highest impact on the microstructure of a growing film. The effect of these first two parameters on the microstructure of sputtered thin films has been studied and is schematically represented in the well known structure zone model developed by Thornton (see Figure 5.2) [245]. As can be seen, a higher deposition temperature, leads to denser films (zone T - transition from zone 1 to zone 2) and eventually to polycrystalline films at elevated temperatures (zone 2 resulting from the surface diffusion of adatoms and zone 3 from additional lattice and grain-boundary diffusion). Increasing the pressure delays the onset of zone T and promotes the creation of a more columnar and porous microstructure resulting from shadowing effects (zone 1). As mentioned in Chapter 4, porosity is a prerequisite in order to obtain “good” EC films and therefore the great majority of the samples in this thesis have been deposited at low temperatures and relatively high pressures (the deposition conditions for all samples will be given in their respective chapters). As a result, ion bombardment, which can lead to densification, without needing to be completely eliminated, was not required in the present context. Therefore, no biasing was used during the deposition of my EC films.
En savoir plus

249 En savoir plus

Chemical vapor deposition of organosilicon and sacrificial polymer thin films

Chemical vapor deposition of organosilicon and sacrificial polymer thin films

On a per wafer basis for a base case comparing spin-on and CVD organosilicon low-k dielectric films, chemical consumption was 350% higher for the spin-on deposition method.1o[r]

163 En savoir plus

Patterning of spontaneous rolling thin polymer films for versatile microcapillaries

Patterning of spontaneous rolling thin polymer films for versatile microcapillaries

The very similar scheme of microcontact printing can be used to produce chemical patterns (see 4 ). A PDMS stamp is also produced by soft lithography and inked with a solution of polylysine grafted polyethylene glycol(PLL-g-PEG) labeled with a green fluorescent probe. An oxidized PDMS layer with an additional soft PDMS coating is produced as before. It is exposed briefly to plasma in order to activate the surface with- out altering its mechanical properties. The stamp is dropped on this surface and left for 5 minutes. Circular holes with diameters of 40 µm and 10 µm wide lines are stamped on the flat film. The film can then be rolled normally. The resulting systems were imaged with fluorescent microscopy techniques as displayed on figure 6 . Rolled-up systems are imaged far from the substrate plane so that only the patterns in the tube are seen.
En savoir plus

9 En savoir plus

Conductive polymer film supporting LiFePO4 as composite cathode for lithium ion batteries

Conductive polymer film supporting LiFePO4 as composite cathode for lithium ion batteries

PEDOT-LiFePO4 films were used directly as the cathode without aluminum current collector, 166. binder or carbon additive[r]

21 En savoir plus

Show all 2350 documents...