Lab profile: Richard Hoogenboom, Ghent University

Natural systems use non-covalent and hydrophobic interactions to assemble simple building blocks into complex proteins and cells. Supramolecular chemistry aims to develop synthetic structures that can be ordered or self-assemble into functional systems in an analogous way. Synthetic approaches, moreover, can use more varied and complex building blocks than nature, opening up the way to a diverse range of smart polymer structures for applications such as sensors and diagnostics, drug delivery and responsive hydrogels.

Richard Hoogenboom established the Supramolecular Chemistry Group in the Centre of Macromolecular Chemistry (CMaC) at Ghent University to focus on these fascinating functional systems. He has a PhD from Eindhoven University of Technology and undertook postdoctoral research at RWTH Aachen and Radboud University Nijmegen prior to joining Ghent University in 2010. He has published over 430 articles, holds over 20 patents, and is editor-in-chief of European Polymer Journal. He has received numerous awards including the RSC Polymer Chemistry award, the PI IUPAC young investigator award, the ACS Macromolecules/Biomacromolecules Young Investigator award, and the ACS Carl S. Marvel Creative Polymer Chemistry Award.

He talked to Materials Today about his current research and future plans.

How long has your group been running?

My research group was started in 2010, when I was appointed as professor at Ghent University. When I arrived in Ghent, my group consisted of just myself but, luckily, I managed to secure sufficient funding to build a fully equipped research lab from scratch and take on up to around 10 researchers in a couple of years.

How many staff currently make up your group?

The exact size of the group varies, but usually consists of 15-20 researchers including around 10 PhD students and five postdocs. For me, this is an ideal group size to be able to remain in touch with and informed about the ongoing projects and with all researchers. From experience, a larger group size does not necessarily mean that the science will move more rapidly, simply because my involvement will become significantly less.

What are the major themes of research in your group?

The major overall theme of our research is the development of functional polymer materials based on molecular engineering. The basis of our work is the development of novel polymer structures by synthesizing novel monomers and fundamental understanding of the polymerization mechanisms, as well as post-polymerization modification routes. This provides us with a high level of control over the chemical structure and properties of polymer materials, enabling us to design the right polymer structure for a wide range of specific applications.

More specifically, we focus on poly(2-oxazoline)s, responsive polymers, and supramolecular materials for a variety of applications ranging from biomaterials and drug/gene delivery to sensors and actuators, as well as self-healing materials and additives for concrete.

How and why did you come to work in these areas?

Being trained as a chemical engineer, specialized in organic and polymer chemistry, I have embraced the ability to control polymer properties by designing the molecular structure. Furthermore, I am eager to understand how the exact polymer structure influences these properties, which provides the basis for my interest in living and controlled polymerizations and polymerization kinetics, as it provides further insights into monomer distribution along individual polymer chains.

Besides the fundamental aspects of polymer synthesis and polymer properties, the engineer in me also enjoys developing novel polymers to address challenges for a wide range of applications. The specific application areas are often inspired by scientific discussions and brainstorms with colleagues and friends. In our lab, we perform the design and synthesis of the polymers, as well as the initial application directed tests, to identify the optimal polymers that can be developed further by our collaborators.

What facilities and equipment does your group have?

My lab is fully equipped for state-of-the-art organic and polymer chemistry, as well as characterization of the resulting structures. Furthermore, we have equipment to characterize polymer properties in solution and solid state.

Do you have a favorite piece of kit or equipment?

My favorite piece of equipment has to be the microwave synthesizers as they allow us to make defined polymers in just a couple of minutes.

What do you think has been your most influential work to date?

My most influential work, I believe, is in the area of poly(2-oxazoline)s that we are developing as novel biomaterials and to go beyond PEGylation. More specifically, we developed a procedure that allows the preparation of highly defined higher molar mass poly(2-oxazoline)s, thereby unveiling their potential for various (biomedical) applications. This has been a long-standing challenge in the field that many experts thought could not be achieved, but which I took up when I started at Ghent.

What is the key to running a successful group?

For me, it is key to create the right atmosphere and group dynamics in the lab so that researchers enjoy their science and feel confident enough to share ‘crazy’ ideas, as well as challenging each other. In addition, I give a lot of freedom to the researchers in my group, allowing them to develop their own independence and creativity. Of course, I am always available for discussion of ongoing work and future plans. You could say that I try to teach them to swim without drowning!   

How do you plan to develop your group in the future?

In the future, I will aim to keep my group in the ideal steady-state size of 15-20 researchers and we will continue to push the boundaries of polymer chemistry to develop the polymer materials of the future.

Key publications

1. X. Xu, F. A. Jerca, K. Van Hecke, V. V. Jerca, R. Hoogenboom. High compression strength single network hydrogels with pillar[5]arene junction points. Mater. Horizons 7 (2020) 566-573. https://doi.org/10.1039/C9MH01401B
2. O. Sedlacek, K. Lava, B. Verbraeken, S. Kasmi, B. G. De Geest, R. Hoogenboom. Unexpected Reactivity Switch in the Statistical Copolymerization of 2-Oxazolines and 2-Oxazines Enabling the One-Step Synthesis of Amphiphilic Gradient Copolymers. J. Am. Chem. Soc. 141 (2019) 9617-9622. https://doi.org/10.1021/jacs.9b02607
3. P. H. M. Van Steenberge, O. Sedlacek, J. C. Hernández-Ortiz, B. Verbraeken, M.-F. Reyniers, R. Hoogenboom, D. R. D'hooge. Visualization and design of the functional group distribution during statistical copolymerization. Nat. Commun. 10 (2019) 3641. https://doi.org/10.1038/s41467-019-11368-6
4. X. Xu, F. A. Jerca, V. V. Jerca, R. Hoogenboom. Covalent Poly(2-Isopropenyl-2-Oxazoline) Hydrogels with Ultrahigh Mechanical Strength and Toughness through Secondary Terpyridine Metal-Coordination Crosslinks. Adv. Funct. Mater. 29 (2019) 1904886. https://doi.org/10.1002/adfm.201904886
5. B. Verbraeken, J. Hullaert, J. van Guyse, K. Van Hecke, J. Winne, R. Hoogenboom. The Elusive Seven-Membered Cyclic Imino Ether Tetrahydrooxazepine. J. Am. Chem. Soc. 140 (2018) 17404-17408. https://doi.org/10.1021/jacs.8b10918
6. B. D. Monnery, V. V. Jerca, O. Sedlacek, B. Verbraeken, R. Cavill, R. Hoogenboom. Defined High Molar Mass Poly(2-Oxazoline)s. Angew. Chem. Int. Ed. 57 (2018) 15400-15404. https://doi.org/10.1002/anie.201807796
7. G. Morgese, B. Verbraeken, S. N. Ramakrishna, Y. Gombert, E. Cavalli, J.-G. Rosenboom, M. Zenobi-Wong, N. D. Spencer, R. Hoogenboom, E. M. Benetti. Chemical Design of Non-Ionic Polymer Brushes as Biointerfaces: Poly(2-oxazine)s Outperform Both Poly(2-oxazoline)s and PEG. Angew. Chem. Int. Ed. 57 (2018) 11667-11672. https://doi.org/10.1002/anie.201805620
8. L. De Smet, G. Vancoillie, P. Minshall, K. Lava, I. Steyaert, E. Schoolaert, E. Van De Walle, P. Dubruel, K. De Clerck, R. Hoogenboom. Plasma dye coating as straightforward and widely applicable procedure for dye immobilization on polymeric materials. Nat. Commun. 9 (2018) 1123. https://doi.org/10.1038/s41467-018-03583-4
9. K. Belal, F. Stoffelbach, J. Lyskawa, M. Fumagalli, D. Hourdet, A. Marcellan, L. De Smet, V. R. de la Rosa, G. Cooke, R. Hoogenboom, P. Woisel. Recognition-Mediated Hydrogel Swelling Controlled by Interaction with a Negative Thermoresponsive LCST Polymer. Angew. Chem. Int. Ed. 55 (2016,  13974. https://doi.org/10.1002/anie.201605630
10. P. H. J. Kouwer, M. Koepf, V. A. A. Le Sage, M. Jaspers, A. M. van Buul, Z. H. Eksteen-Akeroyd, T. Woltinge, E. Schwartz, H. J. Kitto, R. Hoogenboom, S. J. Picken, R. J.M. Nolte, E. Mendes, A. E. Rowan. Responsive biomimetic networks from polyisocyanopeptide hydrogels. Nature 493 (2013) 651-655. https://doi.org/10.1038/nature11839