Molecular-Level Processing of Conjugated Polymers. 2. Layer-by-Layer Manipulation of In-Situ Polymerized p-Type Doped Conducting Polymers

1995 ◽  
Vol 28 (21) ◽  
pp. 7115-7120 ◽  
Author(s):  
A. C. Fou ◽  
M. F. Rubner
Keyword(s):  
Conducting Polymers ◽  
Conjugated Polymers ◽  
Molecular Level ◽  
Layer By Layer ◽  
P Type

Influence of pyrrole feeding ratios on physicochemical characteristics of high-performance multilayered PPy/PVC/PDA@FG-NH2 nanocomposites

2019 ◽  
Vol 33 (10) ◽  
pp. 1358-1382
Author(s):  
Asima Naz ◽  
Rabia Sattar ◽  
Muhammad Siddiq ◽  
Muhammad Abid Zia
Keyword(s):  
Conjugated Polymers ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Oxidative Polymerization ◽  
Physicochemical Characteristics ◽  
Layer By Layer ◽  
X Ray ◽  
Melting And Crystallization ◽  
Scanning Electron

Nanocomposites of conjugated polymers polypyrrole (PPy) and polyvinyl chloride (PVC) as matrices and 1,4-phenylenediamine (PDA) as a linker with amine functional graphite (FG-NH2) as filler have been efficiently fabricated using in situ oxidative polymerization, and the effect of various mass ratios on physicochemical characteristics of prepared nanocomposite was investigated. The layer-by-layer oxidative polymerization of various matrices on host filler surface is confirmed by Fourier transform infrared, energy dispersive X-ray, and X-ray photoelectron spectroscopy examinations. Field emission scanning electron microscopy revealed fibrillary morphology of obtained nanocomposites. Thermal stability, glass transition temperature, and melting and crystallization temperature of the nanocomposites were increased with the incorporation of modified graphite. Brunauer–Emmett–Teller analysis explored the improved adsorption capacity (128 cm3 g−1) of the nanocomposite with higher feeding ratio of pyrrole. The influence of FG-NH2 and pyrrole on electrical conductivity performance of composites was also investigated. Functionalized graphite in the resultant PPy/PVC/PDA@FG-NH2 nanocomposites played an important role in forming conducting network in PPy matrix indicating synergistic effect between PPy and FG-NH2.

Chemical, Electrical, and Structural Properties of Au/Pd Contacts on Chemical Vapor Cleaned p-type GaN Surfaces

2001 ◽  
Vol 693 ◽  
Author(s):  
P. J. Hartlieb ◽  
A. Roskowski ◽  
B. J. Rodriguez ◽  
R. J. Nemanich ◽  
R. F. Davis
Keyword(s):  
Surface Roughness ◽  
High Temperature ◽  
Chemical Vapor ◽  
Ex Situ ◽  
Contact Structures ◽  
Layer By Layer ◽  
Microstructural Stability ◽  
Semiconductor Interface ◽  
P Type

AbstractThe chemical, electrical, and microstructural properties of Au/Pd contacts on p-type GaN(0001) surfaces previously cleaned either ex situ or ex situ and in situ have been investigated. The in situ process involved a high temperature, NH3-based chemical vapor clean (CVC); it produced ordered, stoichiometric, p-type GaN surfaces with no detectable C and an O constituent which was subsequently reduced from 15 at% on the ex situ treated surface to 2 ± 1 at% following the CVC process. The Pd contacting layer grew epitaxially in a layer-by-layer mode on the CVC surface and formed an abrupt, unreacted metal-semiconductor interface. The Au capping layer also grew epitaxially on the Pd. Au/Pd contacts on both HCl and CVC treated surfaces exhibited identical surface roughness values (RMS) in the as-deposited state and following a 500°C anneal. Contact structures on CVC treated surfaces demonstrated excellent high-temperature microstructural stability as evidenced by the absence of significant change in the surface roughness (RMS) with successive annealing at 600 and 700°C. Identical contact structures on ex situ cleaned surfaces exhibited poor high temperature microstructural stability, as indicated by a significant increase in the surface roughness (RMS) following successive anneals at 600 and 700°C. There was a significant degradation in the morphology of both surfaces following the 800°C anneal as evidenced by the formation of large voids in the contact metallization and the exposure of the underlying p-type GaN substrate. The lowest resistance contact structures with uniform metal coverage were obtained for Au/Pd contacts on a CVC treated surface annealed at 700°C.

Molecular-Level Control in The Deposition of Ultrathin Films of Highly Conductive, In-Situ Polymerized P-Doped Conjugated Polymers

1993 ◽  
Vol 328 ◽  
Author(s):  
A. C. Fou ◽  
D. L. Ellis ◽  
M. F. Rubner
Keyword(s):  
Conducting Polymers ◽  
Conjugated Polymers ◽  
Ultrathin Films ◽  
Self Assembly ◽  
Oxidative Polymerization ◽  
Multilayer Films ◽  
Solution Chemistry ◽  
Level Control ◽  
Multilayer Architecture

ABSTRACTA novel thin film processing technique has been developed for the fabrication of ultrathin films of conducting polymers with angstrom-level control over thickness and multilayer architecture. Molecular self-assembly of in-situ polymerized conjugated polymers consists of a layer-by-layer process in which a substrate is alternately dipped into a solution of a p-doped conducting polymer (e.g. polypyrrole, polyaniline) and a solution of a polyanion. In-situ oxidative polymerization produces the more highly conductive, underivatized form of the conjugated polymer, which is deposited in a single layer of precisely controlled thickness (30 to 60 Å). The thickness of each layer can be fine-tuned by adjusting the dipping time and the solution chemistry. The surface chemistry of the substrate (e.g. hydrophobic, charged, etc.) also strongly influences the deposition, thereby making it possible to selectively deposit conducting polypyrrole onto well defined regions of the substrates. Typical multilayer films exhibit conductivities in the range of 20–50 S/cm, but samples with conductivities as high as 300 S/cm have been realized. There is no limit to the number of layers that can be built up nor to the complexity of the multilayer architecture of the film; achieved simply by alternating the sequence of dips into solutions of various polycations and polyanions. This new self-assembly process opens up vast possibilities in applications which require large area, ultrathin films of conducting polymers and, more importantly, in applications that can take advantage of the unique interactions achievable in the complex, supermolecular architectures of multilayer films.

Preparation and properties of multilayered polymer/nanodiamond composites via an in situ technique

2014 ◽  
Vol 34 (5) ◽  
pp. 415-429 ◽  
Author(s):  
Rozina Ashraf ◽  
Ayesha Kausar ◽  
Muhammad Siddiq
Keyword(s):  
Conjugated Polymers ◽  
Oxidative Polymerization ◽  
Lithium Ion ◽  
Layer By Layer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Polymer Lithium Ion Batteries ◽  
Exposed Surface Area

Abstract Compared to conventional materials, nanocomposites of conjugated polymers are found to have excellent performance due to a larger exposed surface area. In this study, polyaniline (PANi), polypyrrole (PPy), polythiophene (PTh) and polyazopyridine (PAP)/nanodiamonds (NDs) composites were efficiently synthesized by in situ oxidative polymerization. Physical characteristics of fabricated nanocomposites were explored using Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX) spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). FTIR indicated layer-by-layer oxidative polymerization of various matrices on functional ND (F-ND) surfaces. FESEM revealed the fibrillar (web-like) morphology of multilayered nanocomposites having a granular arrangement of NDs. TGA of multilayered F-NDs/PAP/PANi/PTh showed 10% degradation at an enhanced temperature of 482°C compared with F-NDs/PANi/PPy/PTh (471°C). Improvement in glass transition of layered material was observed from 99°C (NDs/PANi/PPy/PTh) to 121°C (NDs/PAP/PANi/PTh). Functional filler also contributed towards the enhancement in the conductivity of NDs/PAP/PANi/PTh (5.7 S cm-1) relative to NDs/PANi/PPy/PTh (3.7 S cm-1) systems. New conducting composites are potentially important in various applications, including polymer lithium-ion batteries.

Epitaxial growth manner and structure of superconducting oxide films

1990 ◽  
Vol 48 (4) ◽  
pp. 2-3
Author(s):  
Yoshichika Bando ◽  
Takahito Terashima ◽  
Kenji Iijima ◽  
Kazunuki Yamamoto ◽  
Kazuto Hirata ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Film Surface ◽  
High Energy ◽  
Epitaxial Films ◽  
Layer By Layer ◽  
Initial Growth ◽  
In Situ Growth ◽  
High Quality ◽  
Activated Reactive Evaporation

The high quality thin films of high-Tc superconducting oxide are necessary for elucidating the superconducting mechanism and for device application. The recent trend in the preparation of high-Tc films has been toward “in-situ” growth of the superconducting phase at relatively low temperatures. The purpose of “in-situ” growth is to attain surface smoothness suitable for fabricating film devices but also to obtain high quality film. We present the investigation on the initial growth manner of YBCO by in-situ reflective high energy electron diffraction (RHEED) technique and on the structural and superconducting properties of the resulting ultrathin films below 100Å. The epitaxial films have been grown on (100) plane of MgO and SrTiO, heated below 650°C by activated reactive evaporation. The in-situ RHEED observation and the intensity measurement was carried out during deposition of YBCO on the substrate at 650°C. The deposition rate was 0.8Å/s. Fig. 1 shows the RHEED patterns at every stage of deposition of YBCO on MgO(100). All the patterns exhibit the sharp streaks, indicating that the film surface is atomically smooth and the growth manner is layer-by-layer.

Electronic structure studies of conducting polymers by electron energy-loss spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 160-161
Author(s):  
J. Fink
Keyword(s):  
Electronic Structure ◽  
Conducting Polymers ◽  
Conjugated Polymers ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Light Emitting ◽  
One Dimensional ◽  
New Class ◽  
Electrical Conductivities ◽  
Electron Energy Loss

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.

Oblique-incidence Reflectivity Difference (OI-RD) and Leed Studies of Adsorption and Growth of Xe on Nb(110)

2003 ◽  
Vol 780 ◽  
Author(s):  
P. Thomas ◽  
E. Nabighian ◽  
M.C. Bartelt ◽  
C.Y. Fong ◽  
X.D. Zhu
Keyword(s):  
Transition Layer ◽  
Layer Growth ◽  
Flow Mode ◽  
Layer By Layer ◽  
Zeroth Order ◽  
Step Flow ◽  
Low Energy Electron Diffraction ◽  
Oriented Film ◽  
Low Energy Electron

AbstractWe studied adsorption, growth and desorption of Xe on Nb(110) using an in-situ obliqueincidence reflectivity difference (OI-RD) technique and low energy electron diffraction (LEED) from 32 K to 100 K. The results show that Xe grows a (111)-oriented film after a transition layer is formed on Nb(110). The transition layer consists of three layers. The first two layers are disordered with Xe-Xe separation significantly larger than the bulk value. The third monolayer forms a close packed (111) structure on top of the tensile-strained double layer and serves as a template for subsequent homoepitaxy. The adsorption of the first and the second layers are zeroth order with sticking coefficient close to one. Growth of the Xe(111) film on the transition layer proceeds in a step flow mode from 54K to 40K. At 40K, an incomplete layer-by-layer growth is observed while below 35K the growth proceeds in a multilayer mode.

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