Novel analytical method for the crosslinking process: Infrared thermographic analysis of the thermally latent cationic polymerization of a spiroorthoester and a bifunctional oxetane for the construction of a low‐shrinkage curing system

Abstract

Thermal behaviors were monitored by infrared thermographic analysis in the copolymerization of a spiroorthoester and a bifunctional oxetane with thermally latent initiators [benzyl tetrahydrothiophenium hexafluoroantimonate (BTHT) and benzyl 4-hydroxyphenyl methyl sulfonium hexafluoroantimonate (BPMS)]. The copolymerization with BPMS increased the temperature during the copolymerization more than that with BTHT, whereas the exothermicities were lowered with the increase in the initial feed ratio of the spiroorthocarbonate monomer. The high exothermicity in the copolymerization with BPMS is ascribable to the faster propagation of the oxetane monomer with a high heat of polymerization, and this is supported by model reactions and computational calculation.

Long‐term interaction between microglial cells and cochlear nucleus neurons after bilateral cochlear ablation

“…Oxetane has a four‐membered cyclic ether ring and the basicity of its oxygen atom is higher than that of other cyclic ethers, such as epoxide (three‐membered ring), tetrahydrofuran (five‐membered ring), or tetrahydropyran (six‐membered ring) 1. Because of the high basicity, the cationic polymerization of oxetanes proceeds smoothly to afford high‐molecular polyethers in good yields 2–13. Cationic isomerizations of oxetanes with ester, amide, and imide moieties were also reported 14–19.…”

Expanding Monomers as Anti-Shrinkage Additives

“…IR thermography revealed that the addition of PSOE suppressed temperature increases during polymerization, which would lead to thermal runaway and thermal shrinkage. Polymer networks were obtained from the curing reaction of the bifunctional oxetane 1,4-bis(3-ethyloxetanylmethoxy)benzene with PSOE in the ratio of 80:20 with volumetric expansion of 3.7 vol.% [ 77 ].…”

Synthesis and cationic ring‐opening polymerization of oxetane monomer containing five‐membered cyclic carbonate moiety via highly chemoselective addition of CO2

“…In addition, trialkyl aluminum/H 2 O catalytic system gives polyoxetanes with well‐controlled molecular weights . Oxetane monomers also undergo cationic ring‐opening copolymerization with six‐ or seven‐membered heterocyclic compounds such as tetrahydropyran, ε ‐caprolactone, 1,3,2‐dioxathiepane‐2‐oxide, spiroorthoester, and spiroorthocarbonate . In other ring‐opening copolymerizations, linear aliphatic polycarbonate synthesis by coupling of carbon dioxide (CO 2 ) and oxetane monomers is one of the important process because CO 2 is regarded as a cheap and green C1 resource, which is useful especially for phosgene free processes .…”