ROMP is most effective on strained cyclic olefins, because the relief of ring strain is a major driving force for the reaction — cyclooctene and norbornenes are excellent monomers for ROMP, but cyclohexene is very reluctant to form any significant amount of polymer. Norbornenes are favorite monomers for ROMP, as a wide range of monomer functionalities are easily available through Diels-Alder reactions. Careful balance of catalyst, monomer, and other factors can offer excellent control of the polymer structure.
The light gaseous hydrocarbons produced by catalytic cracking are highly unsaturated and are usually converted into high-octane gasoline components in polymerization or alkylation processes. In polymerization, the light olefins propylene and butylene are induced to Two classes of polymerization usually are distinguished.
In condensation polymerizationeach step of the process is accompanied by the formation of a molecule of some simple compoundoften water. In addition polymerizationmonomers react to form a polymer without the formation of by-products.
Addition polymerizations usually are carried out in the presence of catalystswhich in certain cases exert control over structural details that have important effects on the properties of the polymer.
Linear polymers, which are composed of chainlike molecules, may be viscous liquids or solids with varying degrees of crystallinity; a number of them can be dissolved in certain liquids, and they soften or melt upon heating.
Cross-linked polymers, in which the molecular structure is a network, are thermosetting resins i. Both linear and cross-linked polymers can be made by either addition or condensation polymerization. Learn More in these related Britannica articles:Judging from the amount of research activity spawned in academia, and efforts in industry since White et al.
reported the first self-healing polymeric material system,1 there is little doubt that designers of novel polymeric materials find the potential of self-healing functionality intriguing. Ring opening metathesis can employ an excess of a second alkene (for example ethene), but can also be conducted as a homo- or co-polymerization reaction.
The driving force in this case is the loss of ring strain. Living polymerization: A chain polymerization from which chain transfer and chain termination are timberdesignmag.com: In many cases, the rate of chain initiation is fast compared with the rate of chain propagation, so that the number of kinetic-chain carriers is essentially constant throughout the polymerization.
Background Ring-opening metathesis polymerization (ROMP) is one of the most used and studied chain growth polymerizations.1 Unlike the step growth olefin polymerization, acyclic diene metathesis polymerization (ADMET),2 ROMP is highly efficient for strained cycloalkenes because the metathesis equilibrium is shifted highly toward the ring opening .
Cross Metathesis Reaction of Hindered Substrates. Exploiting the ability of the o-tolyl-NHC Hoveyda-Grubbs catalyst to react with hindered substrates, the Grubbs group recently reported a series of cross metathesis reactions between terminal olefins.
IntroductionThe discovery of living anionic polymerization by Michael Szwarc had a tremendous effect on polymer science,.His work facilitated major developments in both synthetic polymer chemistry and polymer physics as it opened an avenue to the production of well-defined polymers with precisely designed molecular architectures and nano-structured morphologies.