Mineto Uchiyama

A metal-free, cationic, reversible addition-fragmentation chain-transfer (RAFT) polymerization was proposed and realized. A series of thiocarbonylthio compounds were used in the presence of a small amount of triflic acid for isobutyl vinyl ether to give polymers with controlled molecular weight of up to 1×10(5) and narrow molecular-weight distributions (Mw /Mn <1.1). This "living" or controlled cationic polymerization is applicable to various electron-rich monomers including vinyl ethers, p-meth

Cationic degenerative chain-transfer polymerization of vinyl ethers and p-alkoxystyrenes was investigated using a series of thioethers as a reversible chain-transfer agent via the equilibrium between a growing carbocationic species and the resulting sulfonium intermediate in the presence of a small amount of triflic acid (TfOH) as a cationogen. The stable thioether, which was easily prepared from isobutyl vinyl ether (IBVE) and n-butanethiol, efficiently controls the molecular weight of the resu

Phosphates and phosphinates mediate cationic RAFT polymerization of vinyl ethers with a small amount of triflic acid <italic>via</italic> a phosphonium intermediate.

Abstract A metal‐free, cationic, reversible addition–fragmentation chain‐transfer (RAFT) polymerization was proposed and realized. A series of thiocarbonylthio compounds were used in the presence of a small amount of triflic acid for isobutyl vinyl ether to give polymers with controlled molecular weight of up to 1×10 5 and narrow molecular‐weight distributions (M w /M n &lt;1.1). This “living” or controlled cationic polymerization is applicable to various electron‐rich monomers including vinyl e

The simultaneous control of molecular weight and tacticity in cationic polymerization remains challenging. Here, we propose a new approach for stereospecific living cationic polymerization by combining cationic reversible addition-fragmentation chain transfer (RAFT) polymerization with thiocarbonylthio compounds and stereospecific cationic polymerization of bulky vinyl ethers with Lewis acid catalysts. In this combined system, the molecular weight was controlled by the RAFT process between the g

We report a novel method to synthesize degradable poly(vinyl ether)s with cleavable thioacetal bonds periodically arranged in the main chains using controlled cationic copolymerization of vinyl ethers with a 7-membered cyclic thioacetal (7-CTA) via degenerative chain transfer (DT) to the internal thioacetal bonds. The thioacetal bonds, which are introduced into the main chain by cationic ring-opening copolymerization of 7-CTA with vinyl ethers, serve as in-chain dormant species to allow homogene

A combination of hydrogen chloride adduct of isobutyl vinyl ether (IBVE-HCl) and various metal salts (AgOTf, AgPF₆, AgSbF₆, NaBArF (BArF: [3,5-(CF₃)₂Ph]₄B)) efficiently generated initiating cationic species with different low, weakly, or non-nucleophilic counteranions (OTf^-, PF₆^-, SbF₆^-, BArF^-) and induced a cationic reversible-addition-fragmentation chain-transfer (RAFT) or d

Abstract Thiol‐ene cationic and radical reactions were conducted for 1:1 addition between a thiol and vinyl ether, and also for cyclization and step‐growth polymerization between a dithiol and divinyl ether. p ‐Toluenesulfonic acid (PTSA) induced a cationic thiol‐ene reaction to generate a thioacetal in high yield, whereas 2,2′‐azobisisobutyronitrile resulted in a radical thiol‐ene reaction to give a thioether, also in high yield. The cationic and radical addition reactions between a dithiol and

Core cross-linked star polymers were synthesized<italic>via</italic>cationic RAFT polymerization and three different approaches in combination with a radical RAFT mechanism.

Benzofuran (BzF) is a prochiral, 1,2-disubstituted, unsymmetric cyclic olefin that can afford optically active polymers by asymmetric polymerization, unlike common acyclic vinyl monomers. Although asymmetric cationic polymerization of BzF was reported by Natta et al. in the 1960s, the polymer structure has not been clarified, and there are no reports on molecular weight control. Herein, we report dual control of the optical activity and molecular weight of poly(BzF) using thioether-based reversi

Abstract We report a novel method for synthesizing degradable polymers based on 1,5-shift radical isomerization polymerizations of vinyl ethers with transferable atoms or groups and in-between acid-cleavable ether linkages in the side chains. In particular, vinyl ethers with side chains composed of thiocyano and p -methoxybenzyl ether groups underwent radical isomerization polymerizations via 1,5-shifts, in which a vinyl ether radical abstracted the cyano group intramolecularly to generate a thi

Cationic reversible addition fragmentation chain transfer (RAFT) or DT polymerization is achievable using a series of reversible chain transfer agents, such as thiocarbonylthio compounds, thioethers, and phosphorous esters, in the presence of a small amount of strong protonic acids, such as trifluoromethanesulfonic acid. The protonic acid generates a cationic propagating species, while the chain transfer agent results in stable sulfonium and phosphonium intermediates via the degenerative chain t