China
Africa
Explore chapters and articles related to this topic
via metathesis polymerization: Concepts and applications
Published in Y. Yagci, M.K. Mishra, O. Nuyken, K. Ito, G. Wnek, Tailored Polymers & Applications, 2020
Michael R. Buchmeiser, Frank Sinner, M. Mupa
Among the few techniques suitable for the living polymerization of functional polymers, ring-opening-metathesis polymerization (ROMP) using well defined, high-oxidation state metathesis catalysts based on molybdenum, tungsten [3] and ruthenium [4–9] represented the most attractive one. Two major advantages have to be stated, which demonstrate the high versatility of this polymerization technique [10]. On one hand, ROMP allows the living polymerization of (almost any) functional monomer based on cyclic olefins. This permits the stoichiometric design of block-copolymers including cross-linked polymers. On the other hand, the formation of a certain backbone structure with regard to tacticity and cis-trans-configuration may be predetermined by the choice of a certain initiator [11–13]. These characteristics and the fact, that neither the sterical nor the conformational situation of any monomer are changed in course of the polymerization, lead to a high reproducibility in the synthesis of of these tailor-made materials. Consequently, this facilitates correlations between polymer structure, capacity and the resulting properties. Recently, we described the use of ROMP for the preparation of beaded, functionalized polymers [14, 15] for applications in SPE of organic compounds [16–19] as well as for the selective extraction of lanthanides [20, 21] and transition metals [22, 23]. In the following, some recent results in the preparation of functionalized beaded polymers will be summarized.
Ring-Opening Polymerization and Metathesis Polymerizations
Published in Samir H. Chikkali, Metal-Catalyzed Polymerization, 2017
Polymers for a variety of advanced materials have been made using ROMP. Factors affecting the performance of liquid crystalline polymer-based elastomers and gels, such as microstructure of the polymer backbone, degree of cross-linking, and type and frequency of the mesogen, are difficult to control using conventional polymerization techniques. Side chain liquid crystalline (SCLC) polymers based on ABA-triblock architecture were synthesized using a bimetallic Mo-based initiator.66 Further, liquid crystalline (LC) polymers containing chiral units such as cholesterol show chiral nematic and smectic phases and hence have applications in optoelectronics such as LCD displays and in biomedicine. Surfaces are functionalized with polymer brushes to impart superhydrophobicity, switchable wettability, and anti-fouling properties. Due to its high functional group tolerance, ROMP has been used to grow functional polymers on surfaces for such applications.67,68 Self-healing materials have the ability to heal microcracks formed in a polymer composite material and prevent its failure caused by exposure to UV-irradiation, heat, pressure, and so on. ROMP has been used for self-healing materials. A monomer (norbornene) is encapsulated in a urea-formaldehyde microcapsule that ruptures when a crack propagates and the released monomer is polymerized by the initiator present in the matrix thus filling the crack.69
Design of Bioresponsive Polymers
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Anita Patel, Jayvadan K. Patel, Deepa H. Patel
Industrially imperative products can be produced by the ROMP technique that is a kind of olefin metathesis chain-growth polymerization. The liberation of ring strain in cyclic olefins like cyclopentene or else norbornene is the instigator of the reaction and a broad variety of catalysts has been found.
Self-healing coatings
Published in Surface Engineering, 2023
Lakshmi Gopal, Tirumalai Sudarshan
In two-part healing, the two parts (usually the polymeric precursor and the catalyst) are either separately encapsulated and brought together in case of damage, or one component is encapsulated and the other component is dispersed in the matrix [11]. The ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) using Grubbs’ catalyst is an interesting two-part system that has been extensively studied for use in self-healing coatings. This chemistry is highly effective because of multiple reasons – DCPD is an affordable monomer, it remains in a liquid state at room temperature which allows it to flow smoothly out of microcapsules, and has low volatility, which allows it to remain in the crack and polymerize before evaporating. Additionally, DCPD has a long shelf life due in part to its relative resistance to radical polymerization
Synthesis and characterization of copper oxide nanocrystal via preparation of precursor tri-homo-nuclear inorganic complex
Published in Inorganic and Nano-Metal Chemistry, 2019
Niloufar Akbarzadeh-T, Abouzar Tahkor
Oxide structures with nanometric dimensions exhibit novel physical and chemical properties, with respect to bulk oxide materials, due to the spatial confinement and the proximity of the substrate. Many of them have been described during the past few years.[1,2] The use of organic components in the structural modification of inorganic oxides has been proved a powerful strategy for preparation novel materials in recent years.[3,4] Especially, the organic–inorganic hybrid materials prepared by this method have exhibited intriguing structural motifs and potential applications in catalysis, molecular adsorption, electro-conductive, magnetic, and optical materials.[5–7] Bidentate heterocyclic nitrogenous bases, for example 1,10-phenanthroline, bipyridine, and their derivatives, are important chelating agents in coordination chemistry and often used to synthesize of complexes with different nuclearity and interesting properties. First-row transition metal complexes containing these polypyridyl ligands not only have important biological properties but are also important because of their versatile use as building blocks in the synthesis of metallodendrimers, as molecular scaffolding for supramolecular assemblies, as catalysts, in electrochemistry, and in ring-opening metathesis polymerization.[8–22]
PolyHIPEs for Separations and Chemical Transformations: A Review
Published in Solvent Extraction and Ion Exchange, 2019
Kathryn M. L. Taylor-Pashow, Julia G. Pribyl
A procedure to immobilize ruthenium olefin metathesis catalysts on the surface of polyHIPEs was recently reported.[60] Both first and second-generation Grubbs Ru catalysts were immobilized on the surface of polyHIPEs via alkylidene ligand exchange and tested for their ability to catalyze the ring-opening metathesis polymerization of norbornene and various norbornene derivatives. It was found that the supported catalysts did efficiently catalyze the ROMP reactions studied, which resulted in polyHIPEs grafted with brushes of the Ru catalyst initiated polynorbornyl compounds with up to 97% monomer incorporation. The authors noted that after the ROMP reactions were performed, the catalysts were not reusable for subsequent ROMP reactions but could be further used for other olefin metathesis reactions including ring-closing metathesis (RCM) and self-metathesis (SM).