Alkynyl Substituted Carboranes as Precursors to Boron Carbide Thin Films, Fibers and Composites

1992 ◽  
Vol 271 ◽  
Author(s):  
Stephen E. Johnson ◽  
Xiaoguang Yang ◽  
M. F. Hawthorne ◽  
Kevin J. Thorne ◽  
Haixing Zheng ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Boron Carbide ◽  
Inert Atmosphere ◽  
Uv Exposure ◽  
Derivatives Of

ABSTRACTThe use of alkynyl substituted derivatives of o-carborane as precursors to boron containing ceramics is described. These compounds undergo a thermally or photochemically induced polymerization to afford cross linked polyakynyl-o-carborane derivatives. The increase in molecular weight should allow for increased Tg's and the retention of modelled polymer preforms. In this report, these modification reactions are described. In addition, the retention of molded polymer preforms were analyzed after UV exposure and inert atmosphere pyrolysis.

Chemically Designed, UV Curable Polycarbosilane Polymers

1992 ◽  
Vol 271 ◽  
Author(s):  
Kevin J. Thorne ◽  
Stephen E. Johnson ◽  
Haixing Zheng ◽  
John D. Mackenzie ◽  
M. F Hawthorne
Keyword(s):  
Molecular Weight ◽  
Inert Atmosphere ◽  
Uv Exposure ◽  
Cross Linking ◽  
Substitution Reactions ◽  
High Solubility ◽  
Chemical Route ◽  
Uv Curable ◽  
Polymer Precursors ◽  
C Nmr

ABSTRACTTo prepare new polycarbosilane polymer precursors with high solubility and the capability of UV cross-linking, commercial polycarbosilane was modified by a chemical route. These modifications involved AlCl3 catalyzed chlorination reactions of polycarbosilane's Si-H bonds. The resultant Si-Cl bonds were substituted by a reaction with sodium acetylyde to form Si-C=CH ligands. These ligands are suitable for controlled, free radical initiated cross-linking of the polycarbosilane polymers. The increase in molecular weight should allow for increased Tg's and the retention of polymer pre-forms. In this report, the chlorination of the polycarbosilane polymer and the substitution reactions of polycarbosilane were examined with IR, 29Si and 13C NMR spectroscopy. In addition, the retention of polymer pre-forms were analyzed after UV exposure and inert atmosphere pyrolysis.

Degradation in a Methyl-phenyl Co-Polymeric Polysilane for LED Applications

2003 ◽  
Vol 769 ◽  
Author(s):  
Asha Sharma ◽  
Deepak ◽  
Monica Katiyar ◽  
Satyendra Kumar ◽  
V. Chandrasekhar ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Light Source ◽  
Room Temperature ◽  
Light Exposure ◽  
Room Temperature Photoluminescence ◽  
Pl Spectrum ◽  
Pl Intensity ◽  
Methyl Phenyl

AbstractThe optical degradation of polysilane copolymer has been studied in spin cast thin films and solutions using light source of 325 nm wavelength. The room temperature photoluminescence (PL) spectrum of these films show a sharp emission at 368 nm when excited with a source of 325 nm. However, the PL intensity deteriorates with time upon light exposure. Further the causes of this degradation have been examined by characterizing the material for its transmission behaviour and changes occurring in molecular weight as analysed by GPC data.

scholarly journals Effect of the molecular weight on the depth profiling of PMMA thin films using low‐energy Cs + sputtering

2021 ◽  
Author(s):  
Amal Ben Hadj Mabrouk ◽  
Christophe Licitra ◽  
Antoine Chateauminois ◽  
Marc Veillerot
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Depth Profiling ◽  
Low Energy

Chemistry and Properties of Imide Oligomers from Phenylethynyl-Containing Diamines

2000 ◽  
Vol 12 (1) ◽  
pp. 213-223 ◽  
Author(s):  
J G Smith ◽  
J W Connell
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Research Effort ◽  
Average Molecular Weight ◽  
Number Average Molecular Weight ◽  
Similar Composition ◽  
Imide Oligomers ◽  
Calculated Number

As an extension of work on pendent phenylethynyl-containing imide oligomers, three new diamines containing pendent phenylethynyl groups were prepared and characterized. These diamines were used to prepare pendent and pendent and terminal phenylethynyl imide oligomers via the amide acid route in N-methyl-2-pyrrolidinone at a calculated number average molecular weight of 5000 g mol−1. The pendent phenylethynyl groups were randomly distributed along the oligomer backbone and provided a means of controlling the distance between reactive sites. The imide oligomers were characterized and thermally cured, and the cured polymers evaluated as thin films and compared with materials of similar composition prepared from 3,5-diamino-4′-phenylethynylbenzophenone. This work was performed as part of a continuing research effort to develop structural resins for potential aeronautical applications.

On the “Lamellar” Morphology of Poly(p-Phenylene Terephthalamide) and Poly(p-Phenylene Benzobisthiazole)

1988 ◽  
Vol 134 ◽  
Author(s):  
Eric J. Roche
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Quench Rate ◽  
Lamellar Morphology

ABSTRACTRow-nucleated structures in PPTA and PBZT thin films are compared and their dependence upon quench rate and molecular weight illustrated. It is proposed that the lamellar appearance of the morphology is due to a coherent periodic twisting of fibrillar ribbons. The role of crystallosolvate phases is discussed.

Effect of intense electron and ion irradiation on optical absorption of boron carbide thin films

2018 ◽  
Vol 173 (11-12) ◽  
pp. 1075-1082 ◽  
Author(s):  
Gennady Remnev ◽  
Jindrich Musil ◽  
Vladislav Tarbokov ◽  
Sergey Pavlov ◽  
Fedor Konusov ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Absorption ◽  
Boron Carbide ◽  
Ion Irradiation ◽  
Intense Electron

Enhancement in superconducting properties of Y-Ba-Cu-O thin films by post-annealing in an inert atmosphere

1992 ◽  
Vol 27 (19) ◽  
pp. 5276-5280
Author(s):  
Y. H. Kim ◽  
T. S. Hahn ◽  
S. S. Choi ◽  
S. J. Park
Keyword(s):  
Thin Films ◽  
Inert Atmosphere ◽  
Superconducting Properties ◽  
Post Annealing

scholarly journals METAL COMPLEX TETRAIZOINDOLES AS SENSOR MATERIALS

2002 ◽  
Vol 10 (11) ◽  
pp. 79-87
Author(s):  
Cornel Tarabasanu Mihaila ◽  
Lavinia G. Hinescu ◽  
Cristian Boscornea ◽  
Carmen Moldovan ◽  
Mihai E. Hinescu
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Molecular Weight ◽  
Metal Complex ◽  
Electrical Response ◽  
Average Molecular Weight ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Oxide Semiconductor ◽  
Synthesis Methods

The paper presents the synthetic routes for obtaining some organic semiconductors and their characterization in order to use in thin film deposition for gas sensing devices. An original technique was used to control the molecular weight of polymeric phthalocyanine. We have fabricated devices consisting of evaporated thin films of copper, nickel, and iron phthalocyanines onto interdigital electrodes and estimated the electrical conductivity by in-situ measurements. The films were evaporated onto substrates (gold or aluminum) which were entirely integrated in the standard CMOS (capacitor metal oxide semiconductor) technology. The objectives of this work were to improve the synthesis methods of organic metal-complex tetraizoindoles and their polymers and to evaluate their electrical response and thermal stability as evaporated thin films. We have also investigated the variation of polymers conductivity and sublimation yield with the average molecular weight. We found that for polymeric phthalocyanines, the thermal stability was higher than for Pcs monomers. The stability of polymers increased with the average molecular weight.

Bimodal Temperature Behavior of Structure and Mobility in High Molecular Weight P3HT Thin Films

2009 ◽  
Vol 42 (13) ◽  
pp. 4651-4660 ◽  
Author(s):  
Siddharth Joshi ◽  
Patrick Pingel ◽  
Souren Grigorian ◽  
Tobias Panzner ◽  
Ullrich Pietsch ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Temperature Behavior
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