Interview with Professor Krzysztof Matyjaszewski

Kris Matyjaszewski is a J. C. Warner University Professor of Natural Sciences and Director of the Center for Macromolecular Engineering at Carnegie Mellon University. He prepares advanced materials for biomedical, environmental, and energy-related applications. In 1994, he discovered Cu-mediated atom transfer radical polymerization (ATRP), commercialized in 2004 in the United States, Japan, and Europe. He has coauthored >1200 publications (>180,000 citations, h-index 206) and 68 US patents. He is a member of the National Academy of Engineering, National Academy of Sciences, and European, Australian, Polish, Hungarian, and Georgian Academies of Sciences. He received the 2023 NAS Award in Chemical Sciences, the 2017 Benjamin Franklin Medal in Chemistry, the 2015 Dreyfus Prize in Chemical Sciences, the 2011 Wolf Prize in Chemistry, the 2009 Presidential Green Chemistry Challenge Award, and 11 honorary degrees (www.cmu.edu/maty).

Tang: What first led you to investigate ATRP? Matyjaszewski: During my Ph.D., I worked under Professor Stan Penczek at the Polish Academy of Sciences on the controlled/living cationic ring-opening polymerization of tetrahydrofuran. This was later extended to other heterocyclic and then vinyl monomers. In all of these systems, control relied on a dynamic equilibrium between active and dormant species. Meanwhile, several other systems were developed using similar principles. At that time, control of radical polymerization remained one of the most challenging problems to be solved and with perhaps the largest impact on academia and industry. There were several approaches proposed to do that, including weak reversible bonding in alkoxyamines and organometallic species, mimicking Vitamine B-12 chemistry but they required the use of expensive chain capping agents at stoichiometric amounts. We wanted to use a catalytic process to equilibrate propagating radicals with dormant species. Thus, we adopted from organic chemistry an atom transfer radical addition process and converted it to ATRP with Cubased catalysts. This way we prepared many well-defined (co) polymers with precisely controlled architecture and even extended the concept to the synthesis of bioconjugates and organic-inorganic hybrids.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2023 The Authors. Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.

Tang: Why has ATRP attracted so much attention? What is the new trend of ATRP?
Matyjaszewski: One of the reasons for the very large impact and attention devoted to ATRP, was its simplicity and commercial availability of all reagents, initiators, monomers, and ligands for copper complexes. The second one was the robustness of ATRP, which could be run under very undemanding conditions, using unpurified solvents, even in water and recently in the open air.
When I was a graduate student and a postdoc, I had to learn and use various glassblowing techniques, very carefully purify all components, and work under a vacuum with complete exclusion of moisture and air. It took a few days to make a block copolymer at that time. Now, undergraduate students can make block copolymers by ATRP within only 1 or 2 hours.
New trends in ATRP include expanding the range of monomers and polymeric architectures, reducing the amount of Cu catalysts, and employing more sustainable chemistry, for example, using monomers from renewable resources and also depolymerizing polymers back to monomers.

Tang: What do you think the most exciting or innovative recent developments have been in ATRP?
Matyjaszewski: There are many recent innovative approaches in ATRP They include robust spatiotemporal control using light, electrical current, mechanical forces, or feeding various reducing agents. Very important are environmental aspects such as reducing the amount of Cu catalysts to ppm level and their complete removal or replacement by organic catalysts.
Equally exciting is the preparation of new advanced materials such as supersoft materials, self-healing, or shape memory systems. There have been many new hybrid materials prepared. They include nanoparticles with densely grafted bushes, flat wafers with tens or hundreds-nanometer thick dense uniform layers with amazing lubricity, and especially bioconjugates with proteins, nucleic acids, or even cells or exosomes.

Tang: What are the opportunities and challenges that ATRP faces?
Matyjaszewski: Opportunities were listed above and are related to the most recent developments in synthesis and mechanistic understanding and also new materials prepared Aggregate. 2023;4:e367.
wileyonlinelibrary.com/journal/agt2 1 of 2 https://doi.org/10.1002/agt2.367 by ATRP. The challenges include adaptation in the industry. Although ATRP was commercialized in the United States, Japan, and Europe in 2004, the wide adaptation and use for larger volume markets are slower than anticipated. An interesting opportunity will be in areas requiring very small amounts of specialty materials in the pharmaceutical industry such as bioconjugates which will have reduced immunogenicity, longer circulation time, and targeting specific tissues or cells.

Tang: What is your opinion on fundamental research in an end-product-driven world?
Matyjaszewski: Fundamental research is the most important program as it helps to better understand our world and improve our society and environment. Very crucial are issues related to sustainability and understanding the limited available energy resources.

Tang: Who has influenced you most during your scientific research and why?
Matyjaszewski: My graduate advisor Professor Stan Penczek and Professor Michael Szwarc, an inventor of anionic living polymerization, both influenced my scientific career and taught me how to approach and solve scientific problems in a quantitative way.

Tang: What qualities do you value most in training your students? What impact do you think these qualities will have on his/her scientific research and life?
Matyjaszewski: Perhaps the most important is a passion for research and skillful solving of scientific problems. Of course, very good fundamental training is needed, and a broad education, including knowledge of other related disciplines needed for interdisciplinary research. Equally important are creativity, originality, and coverage of the most recent scientific literature.

C O N F L I C T O F I N T E R E S T S TAT E M E N T
The author declares no conflict of interest.