To celebrate the growth and development of the RSC Applied Polymers community and to highlight the remarkable authors who continue to contribute their high quality work to the journal, we would like to share the opinions and insights of these authors through this introductory blog post. Once dubbed #RSCAppliedfirst50, our blog posts aim to give a voice to the authors behind the research and hope that their insights might shed light upon growing challenges and progress in polymer science and its applications.
In this edition, we hear from Dr Yasuhiro Kohsaka and Dr Mikihiro Hayashi as they discuss their recently published article, ‘Vitrimer-like acrylic glass with fast stress relaxation by high-speed carboxy exchange reaction‘.
Dr Yasuhiro Kohsaka and Dr Mikihiro Hayashi have developed vitrimers-like acrylic glass, that is, crosslinked acrylic polymers with rapid stress relaxation performance and excellent processability. These properties are achieved by fast covalent bond exchanges on methacrylate moieties, known as conjugate substitution reactions.
An interview with Yasuhiro Kohsaka (YK) and Mikihiro Hayashi (MH)
What are your respective roles in this collaborative research?
YK: As an expert in polymer synthetic chemistry, I was responsible for the molecular design and synthetic strategy of the materials. My student, Miu Mizuma, played a central role in evaluating the fundamental physical properties of the synthesized polymers.
MH: I supported this study from the perspective of a polymer physicist working with vitrimers-like materials. I also instructed some of Miu’s experiments, such as rheological analysis.
How did your collaborative research begin?
YK: I originally studied conjugate substitution reactions, which are nucleophilic substitutions at the allylic position of methacrylic compounds. In 2019, we discovered a carboxy exchange reaction based on this chemistry, and have since applied it to polymer synthesis and degradation. We were also interested in extending this concept to vitrimers; however, because we were not familiar with polymer physics or rheology, we felt that collaboration with an expert in these areas was essential.
MH: In 2020, Yasuhiro proposed vitrimers-like materials based on conjugate substitution. I immediately decided to start a collaboration because it sounded interesting to me.
Where do you see your own research going in future?
YK: I once thought that the chemistry of conjugate substitution reactions was largely complete, but this discovery has opened up new possibilities in the field. Although this paper demonstrates impressive physical properties, the reaction system still needs to be refined to make it more robust and practical. There are many aspects to explore, including substrates, catalysts, and production routes, and I am eager to investigate these directions in future work.
MH: The rapid relaxation properties of the system, operated by conjugate substitution reactions, are attractive in many respects, such as efficient healability, recyclability, and reprocessability. In addition, the network skeletons are acrylates or methacrylates, which can be synthesized by precise living polymerization. In this case, a model-like network with precisely controlled chemical and physical features can be obtained, which is beneficial for exploring the correlations between dynamic properties and macroscopic functions. This is my idea for utilizing this network design.
What aspect of your work are you most excited about at the moment?
YK: One particularly exciting moment was when we successfully upcycled commercially available acrylic glass into vitrimer-like materials. This experiment was added during the manuscript revision process, so I am grateful to the reviewers and editors for requesting the additional experiments.
MH: In the previous paper of our first collaboration, conjugate substitution reactions were applied to a low-Tg polyacrylates-based network. The present study reveals applicability to a high-Tg poly(methacrylate)-based network. The experimental validation for both types indicates the broad applicability of conjugate substitution reactions, which is gratifying for me.
In your opinion, what are the most important questions to be answered in your field of research?
YK: One of the most important challenges is identifying optimal atomic arrangements that efficiently promote bond exchange reactions. For dynamic bonds such as disulfides and esters, it is crucial to design not only the exchanging bond itself but also its surrounding molecular environment. In this study, the methacrylate skeleton played an important role by attracting nucleophiles and facilitating the exchange reaction.
MH: For poly(acrylates) or poly(methyl acrylate)s-based vitrimers, the segmental relaxation dominated by Tg can be broadly tunable. On the other hand, the essential correlation between segmental relaxation and bond-exchange–based relaxation has not been well clarified. The present design is thus useful for approaching this issue. In addition, “flow” of bond exchangeable materials has not been well clarified, which must be answered by such model-like systems.
What do you find most challenging about your research?
YK: It may be hard to believe, but one of the most significant challenges I face is securing enough time for research. My responsibilities extend beyond research to include teaching, university administration, and grant applications, which makes it difficult to dedicate uninterrupted time to scholarly work.
MH: I have been conducting research on vitrimers for seven years, but the time available for students to understand vitrimer physics is limited. Developments in vitrimers are advancing very quickly, and it is challenging to bridge the knowledge gap between students and me to enable meaningful discussions.
Dr M. Hayashi (left), Ms M. Mizuma (centre), and Prof. Y. Kohsaka (right).
Vitrimer-like acrylic glass with fast stress relaxation by high-speed carboxy exchange reaction
Yasuhiro Kohsaka, Miu Mizuma and Mikihiro Hayashi
RSC Appl. Polym., 2026, 4, 211-217. DOI: 10.1039/D5LP00241A
Check out Dr M. Hayashi, Ms M. Mizuma and Prof. Y. Kohsaka’s cover artwork in RSC Applied Polymers
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