scholarly journals Stepwise synthesis of a Zr–C–Si main chain polymer precursor for ZrC/SiC/C composite ceramics

RSC Advances ◽  
2022 ◽  
Vol 12 (4) ◽  
pp. 2253-2261
Author(s):  
Qiang Gao ◽  
Cheng Han ◽  
Xiaozhou Wang ◽  
Yingde Wang
Keyword(s):  
Valence State ◽  
Redox Reaction ◽  
Main Chain ◽  
Polymer Precursor ◽  
Polymeric Precursor ◽  
Composite Ceramics ◽  
Chain Polymer ◽  
Stepwise Synthesis

Low valence state Cp2Zr(ii) was firstly obtained by a redox reaction of Cp2ZrCl2 with reductive Mg, which subsequently copolymerized with (CH3)2Si(CH2Cl)2 to form a Zr–C–Si main chain polymeric precursor of polyzirconosilane (PZCS).

Phase Transitions in Smectic Bent-Core Main-Chain Polymer Networks Detected by Dielectric and Ultrasonic Techniques

2015 ◽  
Vol 479 (1) ◽  
pp. 76-81
Author(s):  
V. Samulionis ◽  
Š. Svirskas ◽  
J. Banys ◽  
A. Sánchez-Ferrer ◽  
N. Gimeno ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Main Chain ◽  
Polymer Networks ◽  
Chain Polymer ◽  
Ultrasonic Techniques

Preparation of Ultrafine Copper Particles in Poly (2-Vinylpyridine)

1988 ◽  
Vol 132 ◽  
Author(s):  
Alan M. Lyons ◽  
S. Nakahara ◽  
E. M. Pearce
Keyword(s):  
Polymer Matrix ◽  
Redox Reaction ◽  
Metallic Copper ◽  
Average Diameter ◽  
Decomposition Reaction ◽  
Polymer Precursor ◽  
Scanning Calorimetry ◽  
Copper Particles ◽  
Copper Formate ◽  
Ultrafine Copper

ABSTRACTUltrafine copper particles were prepared by the thermal decomposition of a copper formate-poly(2-vinylpyridine) complex. At temperatures above 125°C, a redox reaction occurs where Cu+2 is reduced to copper metal and formate is oxidized to CO2 and H2. The decomposition reaction was studied by thermogravimetric analysis, differential scanning calorimetry and mass spectrometry. Copper concentrations up to 23 wt% have been incorporated into the polymer by this technique. The presence of the polymeric ligand induces the redox reaction to occur at a temperature 80°C lower than in uncomplexed copper formate. Incorporation of the reducing agent (formate anion) into the polymer precursor enables the redox reaction to occur in the solid state. Films of the polymer precursor were prepared and the formation of metallic copper particles were studied by visible and infrared spectroscopy, x-ray diffraction techniques, and transmission electron microscopy. Results from these measurements indicate that spherical copper particles with an average diameter of 35angstrom are isolated within the polymer matrix. The particles are thermodynamically stable at temperatures up to the decomposition of the polymer matrix (≈350 °C), but oxidize rapidly upon exposure air.

scholarly journals Bis-Tridendate Ir(III) Polymer-Metallocomplexes: Hybrid, Main-Chain Polymer Phosphors for Orange–Red Light Emission

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2976
Author(s):  
Konstantinos Andrikopoulos ◽  
Charalampos Anastasopoulos ◽  
Joannis K. Kallitsis ◽  
Aikaterini K. Andreopoulou
Keyword(s):  
Main Chain ◽  
Light Emission ◽  
Red Light ◽  
Molecular Complexes ◽  
Hydroxyl Groups ◽  
Iridium Complexes ◽  
Light Emitters ◽  
Chain Polymer ◽  
Molecular Weights ◽  
Pyridine Moiety

In this work, hybrid polymeric bis-tridentate iridium(III) complexes bearing derivatives of terpyridine (tpy) and 2,6-di(phenyl) pyridine as ligands were successfully synthesized and evaluated as red-light emitters. At first, the synthesis of small molecular bis-tridendate Ir(III) complexes bearing alkoxy-, methyl-, or hydroxy-functionalized terpyridines and a dihydroxyphenyl-pyridine moiety was accomplished. Molecular complexes bearing two polymerizable end-hydroxyl groups and methyl- or alkoxy-decorated terpyridines were copolymerized with difluorodiphenyl-sulphone under high temperature polyetherification conditions. Alternatively, the post-polymerization complexation of the terpyridine-iridium(III) monocomplexes onto the biphenyl-pyridine main chain homopolymer was explored. Both cases afforded solution-processable metallocomplex-polymers possessing the advantages of phosphorescent emitters in addition to high molecular weights and excellent film-forming ability via solution casting. The structural, optical, and electrochemical properties of the monomeric and polymeric heteroleptic iridium complexes were thoroughly investigated. The polymeric metallocomplexes were found to emit in the orange–red region (550–600 nm) with appropriate HOMO and LUMO levels to be used in conjunction with blue-emitting hosts. By varying the metal loading on the polymeric backbone, the emitter’s specific emission maxima could be successfully tuned.

The formation of a liquid crystalline main chain polymer by means of photopolymerization

1998 ◽  
Vol 24 (3) ◽  
pp. 375-379 ◽  
Author(s):  
J. LUB ◽  
D. J. BROER ◽  
M. E. MARTINEZ ANTONIO ◽  
G. N. MOL
Keyword(s):  
Liquid Crystalline ◽  
Main Chain ◽  
Chain Polymer

Network Scission Processes in Peroxide Cured Methylvinyl Silicone Rubber

1967 ◽  
Vol 40 (2) ◽  
pp. 629-634
Author(s):  
D. K. Thomas
Keyword(s):  
Silicone Rubber ◽  
Elevated Temperatures ◽  
Main Chain ◽  
Methyl Groups ◽  
Chain Polymer ◽  
Filled Rubber ◽  
Oxidative Reactions ◽  
Silica Filler ◽  
Silicone Rubbers ◽  
Hydrolysis Of

Abstract In what appeared to be a complex system it transpires that network scission in methylvinyl silicone rubbers at temperatures below 250° C is due largely to hydrolytic reactions in the main chain polymer. At temperatures of 250° C and above there are indications that a significant amount of scission arises from oxidative reactions in the crosslinks, and that this reaction is catalyzed by acidic residues in the rubber. There is no indication that acidic byproducts of the vulcanization reaction catalyze the hydrolysis of siloxane bonds in the polymer. In conventional heat aging tests in which the rubber remains in an unstrained condition the effects of hydrolysis will only be observed if the concentration of water in the system is allowed to rise. Under these circumstances softening will occur because of a shift in the position of equilibrium in the reaction ∼Si—O—Si—O∼ + H2O→∼Si—OH+ HO—Si—O∼ On aging the material in a well ventilated situation the effects of hydrolysis are not seen and the silicone rubber becomes brittle after long exposure at high temperature. This embrittlement must result from additional crosslinking caused by oxidative reactions in the methyl groups of the main chain polymer. When the rubber is used in compression or tension, hydrolytic scission will affect performance, and in applications of this sort it is important to dry the rubber before use and prevent access of moisture to the component during use. With filled rubber the silica filler is a further source of moisture and drying needs to be carried out at elevated temperatures immediately before use. In order to improve the confined heat aging performance of silicone rubber an alternative filler to fine silica is needed which does not have the same affinity for water. It may be, however, that ability to reinforce silicone rubber and affinity for water are inseparable.

Reversible photo-controlled mass transfer in a photo-responsive conjugated main-chain polymer film for high contrast surface patterning

2013 ◽  
Vol 4 (21) ◽  
pp. 5382 ◽  
Author(s):  
Ruiyang Zhao ◽  
Xuepeng Zhan ◽  
Jia Yao ◽  
Guannan Sun ◽  
Qidai Chen ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Polymer Film ◽  
Main Chain ◽  
Surface Patterning ◽  
High Contrast ◽  
Chain Polymer
Sign in / Sign up

Export Citation Format

Share Document