tert‐Butyl Esters as Potential Reversible Chain Transfer Agents for Concurrent Cationic Vinyl‐Addition and Ring‐Opening Copolymerization of Vinyl Ethers and Oxiranes

Abstract

tert‐Butyl esters are demonstrated to function as chain transfer agents (CTAs) in the cationic copolymerization of vinyl ether (VE) and oxirane via concurrent vinyl‐addition and ring‐opening mechanisms. In the copolymerization of isopropyl VE and isobutylene oxide (IBO), the IBO‐derived propagating species reacts with tert‐butyl acetate to generate a copolymer chain with an acetoxy group at the ω‐end. This reaction liberates a tert‐butyl cation; hence, a polymer chain with a tert‐butyl group at the α‐end is subsequently generated. Other tert‐butyl esters also function as CTAs, and the substituent attached to the carbonyl group affects the chain transfer efficiency. In addition, ethyl acetate does not function as a CTA, which suggests the importance of the liberation of a tert‐butyl cation for the chain transfer process. Chain transfer reactions by tert‐butyl esters potentially occur reversibly through the reaction of the propagating cation with the ester group at the ω‐end of another chain.

Living Cationic Ring-Opening Homo- and Copolymerization of Cyclohexene Oxide by “Dormant” Species Generation Using Cyclic Ethers as Lewis Basic Additives

“…However, the polymerization was not controlled, and a product with a low M n value was obtained. A polymer with a lower M n value and a broader MWD than the polymers obtained with cyclic ethers was produced in the presence of VAc (entry 18; simple esters, such as ethyl acetate, were not used because of the possible function as a chain transfer agent , ). Benzoates or haloacetates would be useful for more detailed investigation of the effects of basicity of ester additives.…”

Photoinduced Free Radical Promoted Cationic RAFT Polymerization toward “Living” 3D Printing

“…This result may be due to the change in the structure of the R group in the cationic RAFT agent after insertion of an epoxy monomer, which forms an R group with poor leaving ability and leads to uncontrolled polymerization. 35,36 Next, this photoinduced free radical-promoted cationic RAFT polymerization was considered for constructing a 3D printing system. The SLA method was adopted to accomplish our purpose.…”

“…Relatively lower molecular weights and broad MWDs were found in the polymerization of epoxy monomers (CHOs; entry 5, Table S5). This result may be due to the change in the structure of the R group in the cationic RAFT agent after insertion of an epoxy monomer, which forms an R group with poor leaving ability and leads to uncontrolled polymerization. , …”

Anionic Hybrid Copolymerization of Cyclic and Vinyl Monomers without Transesterification

“…[10][11][12][13] In 2013, Aoshima and co-workers reported the cationic hybrid copolymerization (CHcP) of vinyl ether (VE) and alkylene oxide. [14][15][16][17][18] The rational design of monomer structures and initiation systems is the key to realize the crossover between cationic vinyl-addition polymerization of vinyl ether and cationic ring opening polymerization of alkylene oxide. Recently, You et al reported a radical/anionic hybrid copolymerization (RAHcP) by employing trithiocarbonate as both a chain transfer agent for radical reversible addition-fragmentation chain transfer polymerization of vinyl monomers and an initiator of ROP simultaneously.…”

“…[ 10–13 ] In 2013, Aoshima and co‐workers reported the cationic hybrid copolymerization (CH c P) of vinyl ether (VE) and alkylene oxide. [ 14–18 ] The rational design of monomer structures and initiation systems is the key to realize the crossover between cationic vinyl‐addition polymerization of vinyl ether and cationic ring opening polymerization of alkylene oxide. Recently, You et al.…”