High chain-end fidelity in sono-RAFT polymerization

Abstract

The chain-end fidelity of polymers synthesized via the sono-RAFT technique in an aqueous medium was investigated by performing chain extension studies and preparation of multi-block copolymers. Sono-RAFT polymerization of N,N-Dimethylacrylamide...

Synthesis of star polymers using ultrasound‐induced RAFT polymerization

“…The formation of these highly reactive radicals aids in the initiation of a controlled polymerization reaction 18,48 . Our recent publication on sono‐RAFT indicated that using this technique, well‐defined polymers with high chain‐end fidelity can be prepared in a short period of time 49 . In this article, star polymers are generated using the arm‐first approach and the Sono‐RAFT technique to provide an efficient means to generate CCS polymers with a much higher reaction rate.…”

Ultrasound-Assisted RAFT Polymerization in a Continuous Flow Method

“…Therefore, it is complementary with other mecha-nisms, such as the photoiniferter RAFT process that is free of initiators or metal-free RDRP processes. 51,66,67 A critical drawback of Sono-RAFT, however, is that poor cavitational efficiency at higher viscosity limits the approach to solutions of a low concentration. Evidence for this comes from our previous study, where polymers with a higher monomer concentration (>2.5 M) could not be synthesized using Sono-RAFT.…”

“…Traditionally, RAFT polymerization is initiated using thermal energy, , light, , enzyme, , redox, , and magnetic field. , We recently developed a method to initiate RAFT polymerization using ultrasonic irradiation to generate a low concentration of radicals . The application of ultrasound in polymerization processes is a versatile technique that can be utilized across a diverse array of monomers, − solvents, − and polymerization methodologies. These include free-radical polymerization, − ring-opening polymerization, , and RDRP, − among others.…”

“…The aforementioned outcomes are attained through diverse ultrasound modalities, including but not limited to cavitation, vibration, radiation, acoustic scattering, and acoustic streaming . Ultrasound-assisted RAFT (Sono-RAFT) generates cavitation in water, which stimulates water sonolysis and generates several physicochemical changes, including radical generation. − ,,, When rarefactive negative pressure exceeds the attractive forces between water molecules, a cavity forms, which is filled with solvent vapor, dissolved gas, or both. The cavities continue to grow until they form large cavitation bubbles, which expand to unstable sizes until they violently collapse, generating zones and shock waves of high temperatures.…”

“…The utilization of aqueous media for polymerization and the lack of external initiators or catalysts make ultrasound-mediated polymerization a sustainable process. Therefore, it is complementary with other mechanisms, such as the photoiniferter RAFT process that is free of initiators or metal-free RDRP processes. ,, …”