Ring Opening Olefin Metathesis

Ring Opening Olefin Metathesis-70
Cyclic olefins form polymers (copolymers) of a high tacticity in a presence of this catalyst [14].

Living polymerization with ring opening metathesis is terminated by removing the transition metal from the end of the growing chain and its further deactivation.

Deactivation in this case involves the formation of a complex unable to initiate polymerization [5].

ROMP polymers are characterized by high molecular weights and a narrow MMD, as well as for products of other living polymerizations [11].

Up until the mid-1970s, the information about the structure of the active center of olefin metathesis catalysts was not known.

Intermolecular and intramolecular chain transfers are two main side reactions of ROMP (Scheme 2).

During the intermolecular transferring, the active metal-carbene complex located at the end of one macromolecule interacts with the double bond of the adjoined macromolecule, which leads to fragment exchange process.In this case, the entropy factor must be properly reduced in order to implement the direct process by increasing the monomer concentration or decreasing the temperature of the process [9].Secondary metathesis reactions can occur in addition to the main described reactions during the polymerization process.The next step is a formation of a metal-cyclobutane intermediate.This process occurs in each act of addition of the monomer during the chain growth.Ring opening metathesis polymerization (ROMP) is a process of one or more cyclic olefins transformation to polymer catalyzed by metal carbene compounds.Indeed, the number of double bonds both in polymer and in monomer is equal [1, 2, 3, 4]. Wiley Online Library requires cookies for authentication and use of other site features; therefore, cookies must be enabled to browse the site.Detailed information on how Wiley uses cookies can be found in our Privacy Policy.The listed side reactions, eventually, lead to a broadening of the molecular mass distribution (MMD) and a decrease in a molecular weight of the polymer [10].The chain transfer as well as the spontaneous termination of the growing chain is highly improbable, so ROMP is a living polymerization.


Comments Ring Opening Olefin Metathesis

The Latest from mediashkola-plus.ru ©