Which shows polymerization by ring-opening?

Cationic ring-opening polymerization Examples of cyclic monomers that polymerize through this mechanism include lactones, lactams, amines, and ethers. CROP proceeds through an SN1 or SN2 propagation, chain-growth process. The mechanism is affected by the stability of the resulting cationic species.

Which compounds undergo ring-opening polymerization?

The cyclic monomer structures that can be used for ring-opening polymerization include alkanes, alkenes, and compounds containing heteroatoms from different groups, for example, the sulfur family (polysulfur, sulfides, etc.), the nitrogen family (amines, amides, imides, etc.), the oxygen family (acetals, ethers, esters …

What is ring-opening polymerization of caprolactam?

The ring-opening polymerization of caprolactam is more complex; the proposed mechanism involves the abstraction of an acidic H-N proton from the caprolactam in the presence of a strong base. The activated monomer anion then attacks another lactam molecule to induce ring-opening.

What is the importance of ring-opening polymerization reaction?

Ring-opening polymerization offers an alternate to step polymerization for the synthesis of many polymers. Thus, polyesters can be produced either by ring-opening polymerization of lactones as well as step polymerization of diacids with diols.

What is radical ring-opening polymerization?

Radical ring-opening polymerization (rROP) combines the advantages of both ring-opening polymerization and radical polymerization, that is the preparation of polymers bearing heteroatoms in the backbone but with the ease and robustness of a radical process.

What is a cyclic monomer?

Cyclic monomers constitute a broad family of monomers which are able to be polymerized by anionic ring-opening polymerization or related nucleophilic ring-opening mechanism.

What is anionic ring-opening polymerization?

Anionic ring-opening polymerization is a kind of chain growth polymerization where the initiation and propagation steps accompany ring-opening reaction of cyclic monomers induced by nucleo- philic addition of anionic initiator and anionic chain end, respectively.

What is a ring-opening reaction?

Ring-opening reactions of epoxides by a halide ion are important transformations that afford a 1,2-halohydrin system with two successive chiral carbon centers. The obtained products may be converted to various functional groups (Figure 1) and used as synthetic intermediates for natural products and pharmaceuticals.

Is ring-opening exothermic or endothermic?

The MP2 and DFT calculations of the noncatalyzed reaction predicted an activation barrier of approximately 20−21 kcal/mol for epoxide ring opening depending on the carbon center undergoing reaction. This reaction is not favorable and is endothermic.