Abstract
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.
| Original language | English |
|---|---|
| Article number | 1800240 |
| Number of pages | 7 |
| Journal | Macromolecular Rapid Communications |
| Volume | 39 |
| Issue number | 19 |
| DOIs | |
| Publication status | Published - 1 Oct 2018 |
Funding
This study was largely conducted by AA while at CSIRO under an Industrial Traineeship. Y.Z. acknowledges funding under the China Scholarship Council-CSIRO Joint Scholarship Program. The authors are grateful to Jo Cosgriff and Roger Mulder for NMR, Carl Braybrook for mass spectrometry and Pam Hoobin for chromatography during various stages of this work.
Keywords
- radical polymerization
- RAFT
- sequence defined polymers
- single unit monomer insertion
- Pentanoic Acids/chemistry
- Light
- Polymerization
- Kinetics
- Acrylamides/chemistry
- Photochemical Processes