Ring‐Opening Polymerization

Abstract

A wide variety of cyclic monomers have been successfully polymerized by the ring-opening process [Frisch and Reegan, 1969; Ivin and Saegusa, 1984;Saegusa and Goethals, 1977]. This includes cyclic amines, sulfides, olefins, cyclotriphosphazenes, and N-carboxy-a-amino acid anhydrides, in addition to those classes of monomers mentioned above. The ease of polymerization of a cyclic monomer depends on both thermodynamic and kinetic factors as previously discussed in Sec. 2-5.The single most important factor that determines whether a cyclic monomer can be converted to linear polymer is the thermodynamic factor, that is, the relative stabilities of the cyclic monomer and linear polymer structure [Allcock, 1970;Sawada, 1976]. Table 7-1 shows the semiempirical enthalpy, entropy, and free-energy changes for the conversion of cycloalkanes to the corresponding linear polymer (polymethylene in all cases) [Dainton and Ivin, 1958;Finke et al. 1956]. The lc (denoting liquid-crystalline) subscripts of ÁH, ÁS, and ÁG indicate that the values are those for the polymerization of liquid monomer to crystalline polymer.Polymerization is favored thermodynamically for all except the 6-membered ring. Ringopening polymerization of 6-membered rings is generally not observed. The order of thermodynamic feasibility is 3,4 > 8 > 5,7 which follows from the previous discussion (Sec. 2-5c) on bond angle strain in 3-and 4-membered rings, eclipsed conformational strain in the 5-membered ring, and transannular strain in 7-and 8-membered rings. One notes that RING-OPENING POLYMERIZATION RING-OPENING POLYMERIZATION

Recyclable and (Bio)degradable Polyesters in a Circular Plastics Economy

“…It is typically a chain-growth polymerization process that is initiated through the ring opening of a cyclic monomer with an initiator to generate a reactive center. Further cyclic monomers can then be added to this reactive center, leading to the formation of a longer polymer chain . Distinct from SGP, ROP offers several advantages, including milder reaction conditions (low temperatures, ambient pressure), faster kinetics, higher yield, and 100% atom economy, as well as precise control over polymer molar mass, dispersity, end-group fidelity, regio- and stereoregularity, and architecture. , Although most cyclic esters do not occur naturally, certain bioderived platform chemicals can be utilized for their synthesis. , As such, ROP is a highly efficient and environmentally friendly route for the synthesis of aliphatic polyesters.…”

Towards durable practical lithium–metal batteries: advancing the feasibility of poly-DOL-based quasi-solid-state electrolytes via a novel nitrate-based additive

“…The successful completion of these two steps is crucial in determining whether cyclic ether molecules can be effectively polymerized. 31 Subsequently, the tertiary oxonium ion links to another monomer molecule, forming another tertiary oxonium ion and propagating the polymerization until completion.…”

“…It is well known that not all cyclic ether molecules can complete the initiation phase, as their ability to undergo the ring-opening step is primarily determined by the level of ring strain present in the molecule. 31 Previous research suggests that cyclic ethers with three-and four-membered rings have high ring strain and are more likely to complete the initiation Energy & Environmental Science Paper step, whereas those with five-and six-membered rings tend to have lower ring strain and are, thus, more prone to failing the initiation phase. 32 Therefore, as DOL is a five-membered cyclic ether, its ring-opening polymerization can be easily compromised by molecular structure changes.…”

Cationic Emulsion Polymerization of Octamethylcyclotetrasiloxane (D4) in Mixtures with Alkoxysilanes

“…The cationic polymerization of octamethylcyclotetrasiloxane (D4) catalysed by acids leads to the formation of polydimethylsiloxane (PDMS), though higher molecular weight cyclosiloxanes are also formed as side products ( Figure 1 ) [ 1 , 2 , 3 , 4 ].…”

“…The emulsion polymerization of D4, first described in 1959 [ 5 ], is preferred over polymerization carried out in bulk because, usually, the monomer conversion is higher, the polymer molecular weight (MW) distribution is lower and less cyclic oligomers of a higher MW than D4 are formed [ 6 ]. When dodecylbenzenesulfonic acid (DBSA) is applied as a surfactant and at the same time as a polymerization initiator, the cationic emulsion polymerization proceeds smoothly at a relatively low temperature [ 1 , 3 , 4 , 6 , 7 , 8 , 9 ].…”