Date: 28 May 2026 | Categories: Headline News, uv-150, News
Authors: Mia D. Hall, Bo Zhang, Evelina Liarou, Tanja Junkers,* and David Haddleton*
Professors David Haddleton, from the University of Warwick, and Tanja Junkers, from the University of Monash, have successfully used a continuous flow platform – the Vapourtec UV-150 photochemical reactor – to perform a photoinduced copper-mediated reversible deactivation radical polymerisation (photoinduced Cu-RDRP) to enable facile, controlled, polymerisation of polyacrylates in a user-friendly setup.
A wide range of functional groups is tolerated and relatively mild reaction conditions can be utilised, supporting widespread potential applicability. Inline NMR measurements enabled real-time kinetic screening and the impact of variations in target molecular weight (MW), monomers, side-chain functionalities and solvent switches were monitored alongside efficacy of polymer block formation.[1]
Scheme 1: Haddleton and Junkers’ user-friendly automated flow polymerization platform with real-time inline reaction monitoring
Photochemistry in flow
The recent application of photochemical reactors within continuous flow has revolutionised the field and provoked an explosion of research. Under traditional batch operation, photochemical reactions suffer limited light penetration and inconsistent heat dissipation, frequently leading to issues with scalability, irreproducibility and poor reaction control. Flow chemistry enables greater control over both light penetration and temperature, due to higher surface-to-volume ratios, improved mixing, and uniform light penetration, leading to more predictable scale-up.[2]
Research applying continuous flow methodology in photoinduced-RDRPs has focussed particularly on photoinduced reversible-fragmentation chain-transfer (RAFT) and atom transfer radical polymerization (ATRP) transformations. Using flow methodology brings several advantages including synthesis of well-defined polymers with control of chain length, the ability to incorporate complex molecular architectures and utilisation of mild reaction conditions, as well as tolerance to a wide range of functional groups.
Photoinduced Cu-RDRP for controlled polymerisation
The use of photoinduced Cu-RDRP under continuous flow conditions reported by Junkers and co-workers resulted in high monomer conversion with short residence times and excellent polymer definition.[3, 4] Haddleton and co-workers undertook similar work, but were able to remove the requirement for rigorous deoxygenation through high loadings of a copper complex.[5] In both cases, the implementation of real-time monitoring in combination with continuous flow offered the possibility of facile inline analysis, negating the requirement to stop the reaction and sample manually. In particular, the exploitation of inline 1H NMR analysis allows real-time monitoring of monomer conversion and correlation of reaction kinetics in relation to flow rates and residence times, facilitating optimisation of higher-throughput screening. Furthermore, machine-controlled transient time sweeps with real-time data analysis can be executed with Python scripts.
Reaction optimisation using a closed feedback loop
During reaction optimisation, offline NMR samples were compared with inline NMR samples to ensure parity. Minor deviations were detected (±4%), which could be attributed to imprecise integration, incorrect baseline correction, and apodization. It was noted that a low level of deviation may be expected due to the rapid polymerization rate and the time taken to conduct the initial inline 1H NMR scan. Kinetics were also determined and shown to be dependent on final chain-length; shorter chain-lengths in the final product resulted in more uniform kinetics – linear, first-order – for the duration of the experiment, whereas longer chain-lengths only exhibited linear, first-order kinetics over the first 5 minutes, followed by deviation. Well-defined polymers with low dispersity and narrow MW distributions were produced, regardless of the final chain-length. A range of monomer characteristics was tolerated, including hydrophilic, amphiphilic, and hydrophobic monomers, demonstrating the applicability of this platform to synthesise a diverse range of materials.
Continuous flow and inline monitoring: a powerful method for rapid reaction optimisation
The use of the Vapourtec UV-150 reactor for photochemical reactions offers many advantages over the corresponding batch set-up, including:
- Greater reaction control
- Improved mixing
- Improved heat control
- Uniform light penetration
- Facile scale-up
- Precise control over light wavelength
Combination of the Vapourtec UV-150 reactor with inline analysis provides even greater opportunity for rapid reaction screening and optimisation, as well as enabling facile collection of kinetic data. In this study, several parameters were screened simultaneously in real-time, resulting in rapid synthesis of well-defined polymers, with low dispersity at scale. The reported system has the potential to generate complex architectures with tolerance for a range of functional groups using mild reaction conditions. This concept has the potential to be further extended with the application of machine learning (ML) methods in the future.
References:
[1] High-Throughput Kinetic Screening of UV and Visible Light-Induced Copper-RDRP in Continuous Flow Using Inline Benchtop NMR Analysis (M. D. Hall, B. Zhang, E. Liarou, T. Junkers, D. Haddleton, JACS Au, 2026, 6, 2387–2395). https://doi.org/10.1021/jacsau.6c00015
[2] Flow Photochemistry as a Tool in Organic Synthesis (T. H. Rehm, Chem. Eur. J., 2020, 26, 16952–16974). https://doi.org/10.1002/chem.202000381
[3] Photo-induced copper-mediated polymerization of methyl acrylate in continuous flow reactors (B. Wenn, M. Conradi, A. Demetrio Carreiras, D. M. Haddleton, and T. Junkers, Polymer Chem., 2014, 5, 3053–3060). https://doi.org/10.1039/C3PY01762A
[4] Organocatalyzed Photo-Atom Transfer Radical Polymerization of Methacrylic Acid in Continuous Flow and Surface Grafting (G. Ramakers, A. Krivcov, V. Trouillet, A. Welle, H. Möbius and T. Junkers, Macromol. Rapid Commun., 38, 1700423). https://doi.org/10.1002/marc.201700423
[5] Photo-induced copper-RDRP in continuous flow without external deoxygenation (A. Marathianos, E. Liarou, A. Anastasaki, R. Whitfield, M. Laurel, A. M. Wemyss and D. M. Haddleton, Polymer Chem., 2019, 10, 4402–4406). https://doi.org/10.1039/C9PY00945K