For example, if the atom bearing the positive charge is stabilized by electron-donating groups, polymerization will proceed by the S When the amount of monomers becomes depleted, termination can occur intra or intermolecularly.The active end can "backbite" the chain, forming a macrocycle.
Alkyl chain transfer is also possible, where the active end is quenched by transferring an alkyl chain to another polymer.
The mechanism for ROMP follows similar pathways as olefin metathesis.
The mesophase type and the thermal transition temperatures are influenced not only by the attached mesogenic moiety but also by the stiffness of the polymer backbone, the spacer lengths between the main chain and the liquid crystalline entity, the isomerism, the tacticity, and so on.
In addition, the use of acyclic diene metathesis polymerization (ADMET) or alternating diene metathesis polycondensation (ALTMET) offer new possibilities for creating new main chain liquid crystalline polymers (MCLCPs).
Many strained cycloalkenes, e.g norbornene, are suitable monomers via ring-opening metathesis polymerization.
Ring-opening polymerization has been used since the beginning of the 1900s to produce polymers.We use/store this info to ensure you have proper access and that your account is secure.We may use this info to send you notifications about your account, your institutional access, and/or other related products. If you want more info regarding data storage, please contact [email protected] polymerization in which a cyclic monomer yields a monomeric unit which is acyclic or contains fewer cycles than the monomer.Note: If the monomer is polycyclic, the opening of a single ring is sufficient to classify the reaction as ring-opening polymerization.The initiation process involves the coordination of the cycloalkene monomer to the metal alkylidene complex, followed by a [2 2] type cycloaddition to form the metallacyclobutane intermediate that cycloreverts to form a new alkylidene species.(xy) and ΔSp(xy) are the corresponding enthalpy (SI unit: joule per kelvin) and entropy (SI unit: joule) of polymerization, and T is the absolute temperature (SI unit: kelvin).The free enthalpy of polymerization (ΔG is the active monomer.For instance, radical ROP can produce polymers with ethers, esters, amides, and carbonates as functional groups along the main chain.The general mechanism for anionic ring-opening polymerization.Mechanisms and thermodynamics of ring-opening polymerization were established in the 1950s.Additionally, radical ROP is useful in producing polymers with functional groups incorporated in the backbone chain that cannot otherwise be synthesized via conventional chain-growth polymerization of vinyl monomers.