TY - JOUR
T1 - Light-induced RAFT single unit monomer insertion in aqueous solution—toward sequence-controlled polymers
AU - Aerts, Annelore
AU - Lewis, Reece W.
AU - Zhou, Yanyan
AU - Malic, Nino
AU - Moad, Graeme
AU - Postma, Almar
PY - 2018/10/1
Y1 - 2018/10/1
N2 - First report on the sequential, visible light-initiated, single unit monomer insertion (SUMI) of N,N-dimethylacrylamide (DMAm) into the reversible addition fragmentation chain transfer (RAFT) agent, 4-((((2-carboxyethyl)thio)carbonothioyl)thio)-4-cyanopentanoic acid (CTA1), in aqueous solution is provided. The specificity for SUMI over formation of higher oligomers and/or RAFT agent-derived by-products is higher for longer irradiation wavelengths. Red light provides the cleanest product (selective SUMI), showing a linear pseudo-first order kinetic profile to high (>80%) conversion, but also the slowest reaction rate. Blue light provides a relatively rapid reaction, but also gives some by-products (<2%) and the kinetic profile displays a conversion plateau at >65% conversion. Higher specificity with red light is attributed to CTA1 absorbing at longer wavelengths than the SUMI product, which allows selective excitation of CTA1. The use of a higher reaction temperature (65 °C vs ambient) results in a higher reaction rate and a reduction in oligomer formation.
AB - First report on the sequential, visible light-initiated, single unit monomer insertion (SUMI) of N,N-dimethylacrylamide (DMAm) into the reversible addition fragmentation chain transfer (RAFT) agent, 4-((((2-carboxyethyl)thio)carbonothioyl)thio)-4-cyanopentanoic acid (CTA1), in aqueous solution is provided. The specificity for SUMI over formation of higher oligomers and/or RAFT agent-derived by-products is higher for longer irradiation wavelengths. Red light provides the cleanest product (selective SUMI), showing a linear pseudo-first order kinetic profile to high (>80%) conversion, but also the slowest reaction rate. Blue light provides a relatively rapid reaction, but also gives some by-products (<2%) and the kinetic profile displays a conversion plateau at >65% conversion. Higher specificity with red light is attributed to CTA1 absorbing at longer wavelengths than the SUMI product, which allows selective excitation of CTA1. The use of a higher reaction temperature (65 °C vs ambient) results in a higher reaction rate and a reduction in oligomer formation.
KW - radical polymerization
KW - RAFT
KW - sequence defined polymers
KW - single unit monomer insertion
KW - Pentanoic Acids/chemistry
KW - Light
KW - Polymerization
KW - Kinetics
KW - Acrylamides/chemistry
KW - Photochemical Processes
UR - http://www.scopus.com/inward/record.url?scp=85053442062&partnerID=8YFLogxK
U2 - 10.1002/marc.201800240
DO - 10.1002/marc.201800240
M3 - Article
C2 - 29900617
AN - SCOPUS:85053442062
VL - 39
JO - Macromolecular Rapid Communications
JF - Macromolecular Rapid Communications
SN - 1022-1336
IS - 19
M1 - 1800240
ER -