ABC Pseudo-Periodic Sequence Control by Cationic Orthogonal Terpolymerization of Vinyl Ether, Oxirane, and Ketone

Homopolymer-block-Alternating Copolymers Composed of Acrylamide Units: Design of Transformable Divinyl Monomers and Sequence-Specific Thermoresponsive Properties

In this work, we synthesized an acrylamide-based terpolymer that is a block copolymer composed of an AB alternating copolymer and a C homopolymer. The key to the unprecedented achievement is rational design of an acrylate-acrylamide divinyl monomer carrying CF₃-substituted salicylic acid ester bonds (AAm-CF₃) to realize the efficient and selective cyclopolymerization as well as the quantitative transformation of the resultant cyclorepeating units. The selectivity in the cyclopolymerization and the pendant transformation ability were evaluated through reactivity ratios of the corresponding model monomers and quantitative aminolysis reactions of the model compound. The cyclopolymerization via the photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) process with a macrochain-transfer agent and subsequent aminolysis reaction afforded the homopolymer-block-alternating copolymer. The sequence-controlled terpolymer exhibited a very unique thermal response behavior in water that was strikingly different from the corresponding sequence-uncontrolled terpolymers, such as homopolymer-block-statistical copolymers and all statistical terpolymers, despite the fact that the structure cannot be distinguished by ¹H NMR.

Living Anionic Addition Reaction of 1,1-Diphenylethylene Derivatives: One-Pot Synthesis of ABC-type Chain-End Sequence-Controlled Polymers

In this study, a 1:1 addition reaction using 1,1-diphenylethylene (DPE) derivatives, referred to as the "living anionic addition reaction", was established to regulate the sequence of vinyl compounds having negligible homopolymerizability. The stoichiometric and successive addition reaction between a DPE anion and more reactive DPE derivatives proceeded quantitatively when the electrophilicity of the DPE derivatives was sufficiently enhanced by electron-withdrawing groups such as (trimethylsilyl)ethynyl and acyl groups. The relative electrophilicity of the DPE derivatives was predicted by Hammett's law and the β-carbon chemical shifts of the carbon-carbon double bonds. AB- and ABC-type chain-end sequence-controlled polystyrenes with well-defined structures were synthesized by reacting two or three DPE derivatives with difunctional anionic living polystyrene in increasing order of their electrophilicity in a one-pot reaction.

Living cationic polymerization of vinyl ethers initiated by electrophilic selenium reagents under ambient conditions

We present a living cationic polymerization of vinyl ethers utilizing electrophilic selenium reagents as initiators and pentacarbonylbromomanganese (Mn(CO)₅Br) as the catalyst.

Magnesium bromide (MgBr2) as a catalyst for living cationic polymerization and ring-expansion cationic polymerization

Magnesium bromide (MgBr₂) was found to be an effective catalyst for the ring-expansion cationic polymerizations of isobutyl vinyl ether (IBVE) initiated by a “cyclic” hemiacetal ester (HAE) bond-based initiator leading to the syntheses of cyclic poly(IBVE)s.

Stereoselective cationic polymerization of vinyl ethers by easily and finely tunable titanium complexes prepared from tartrate-derived diols: isospecific polymerization and recognition of chiral side chains

Isotactic poly(vinyl ether)s were generated by titanium TADDOLates, which can be prepared from naturally abundant tartaric acid in a facile and economical manner with well-defined structures.