Controlled cationic ring‐opening polymerization of cyclic thiocarbonates with ester groups

Abstract

This work deals with the cationic ring-opening polymerization of the cyclic thiocarbonates 5-benzoyloxymethyl-5-methyl-1,3-dioxane-2-thione (1), 5,5-dimethyl-1,3-dioxane-2-thione (2), and 4-benzoyloxymethyl-1,3-dioxane-2-thione (3). The polymerization was carried out with 2 mol % trifluoromethanesulfonic acid, methyl trifluoromethanesulfonate, boron trifluoride etherate, or triethyloxonium tetrafluoroborate as the initiator to afford the polythiocarbonate with a narrow molecular weight distribution accompanying isomerization of the thiocarbonate group. The molecular weight of the obtained polymer could be controlled by the feed ratio of the monomer to the initiator and increased when the second monomer was added to the polymerization mixture after the quantitative consumption of the monomer in the first stage. The block copolymerization of 2 and 3 was also achieved, and this supported the idea that the cationic ring-opening polymerization of these monomers proceeded via a living process. The order of the polymerization rate was 3 Ͼ 2 Ͼ 1. The cationic ring-opening polymerization of 1 and 3 involved the neighboring group participation of ester groups according to the polymerization rate and molecular orbital calculations with the ab initio method.

Internal Catalysis in Covalent Adaptable Networks: Phthalate Monoester Transesterification As a Versatile Dynamic Cross-Linking Chemistry

“…NGP is a classical principle in organic chemistry and has been studied extensively in bio-organic chemistry, as this is also a mimic or model of enzymatic catalysis. − In general, NGP is the phenomenon where the relative proximity of functional groups within a compound results in an enhancement of a reaction rate . Explicit applications of this principle in polymer chemistry were reported in synthesis, − modification, or hydrolysis, − although they have been rare. Significant rate enhancements have also been observed in CANs that could be related to the adventitious placement of neighboring amines , or hydroxyl groups − within the polymer backbones.…”

Novel Anionic Ring-Opening Polymerization of Seven-Membered Monothiocarbonate Depending on Initiators

“…Earlier works on the polymerization of TCs were carried out for five- 6 and six-membered 7,8 TCs having no substituent, which give rise to isomerization or polymerization giving poorly soluble polymers, respectively. We accordingly carried out detailed investigation on polymerization of TCs with appropriate substituents to control the polymerization. , We have recently reported that cationic polymerization of 1,3-dioxepan-2-thione (7TC) gives a poly(thiocarbonate) through specific isomerization of thiocarbonyl to carbonyl moieties . Although the polymerization proceeds via a controlled fashion, slow termination occurred after complete consumption of the monomer.…”

Study on curing shrinkage and mechanism of DHOM‐modified epoxy‐acrylate‐based UV‐curing 3D printing materials

“…At this time, other DHOM molecular monomers attacked the carbocation from the M direction, the active cation was combined with the oxygen atom in the spiro ring structure of DHOM to form an oxonium ion. This process was repeated all the time to achieve the ring‐opening of the spiro ring structure in DHOM 21–22 …”