In the realm of chemical engineering and material sciences, the behavior of polymeric reacting flows is crucial to a multitude of industrial processes, including the manufacturing of plastics, pharmaceuticals, and coatings. The study of these flows necessitates an acute understanding of the interplay between chemical reactions and material properties such as viscosity and elasticity. Recent research published in The Journal of Physical Chemistry B by Ueki et al. has provided groundbreaking insights into the unpredictable dynamics of polymeric reacting flow by exploring the changes in fluid properties through molecular diagnosis using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) Spectroscopy. Their work reveals the complexities underlying the reaction mechanisms in polymeric systems at ultrahigh molecular weights.

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When a chemical reaction occurs within a flow of polymeric liquid, conventional wisdom suggests that changes in the properties of the fluid—such as viscosity—are likely to translate directly into altered flow dynamics. Specifically, if a polymeric solution undergoes a reaction that reduces its viscosity, the expectation is for an easier flow or reduced resistance to deformation. However, the latest findings published by Ueki et al. defy these expectations. Through meticulous research, the team has shown that a reacting polymeric liquid flow can exhibit a significant temporary increase in viscoelasticity, even when the overall viscosity undergoes a slight reduction post-reaction.

Published on May 6, 2020, in issue 123(21) of The Journal of Physical Chemistry B, this study employs the use of ATR-FTIR spectroscopy, a molecular diagnostic technique that provides detailed information on the composition and structure of materials at the molecular level. The authors, Toshimasa Ueki, Jun Iijima, Satoshi Tagawa, and Yuichiro Nagatsu from the Department of Chemical Engineering at Tokyo University of Agriculture and Technology and the Division of Chemistry at Nihon University School of Medicine, uncovered that this atypical behavior occurs due to a structural change in the side functional group (carboxyl) present in polyacrylamide chains, particularly those with ultrahigh molecular weights (Mw).

The DOI assigned to this pivotal research is 10.1021/acs.jpcb.9b02057, providing a digital object identifier that ensures the paper is uniquely and permanently identified within the digital universe. This DOI can be used to directly access the original study for readers who wish to delve into the details.

The central finding of the study revolves around the nature of the increased viscoelastic behavior. Traditionally, such behavior would signal increased intermolecular interactions, which in turn would be expected to result from higher molecular weights or the creation of cross-linked network structures within the fluid. Surprisingly, the reaction led to no considerable increase in molecular weight nor the creation of substantial cross-linkage. Instead, the reaction fostered a modification in a side functional group in the polymeric chains, suggesting that even minor molecular changes can lead to drastic shifts in macroscopic flow properties.

This counterintuitive increase in viscoelasticity holds significant implications for the processing and manufacturing industries that rely on precise control of flow dynamics. One example is the field of additive manufacturing, where the flow behavior of polymers determines the stability and quality of printed structures. In pharmaceutical manufacturing, the findings could affect how drug carriers are formulated and delivered within the body.

The study methodically employed ATR-FTIR spectroscopy to observe the changes in the functional groups of the polymer during the flow reaction. This in-situ monitoring made it possible to correlate these molecular-scale observations with the macroscopic flow behavior that was observed. The researchers also provided a theoretical framework to explain the observed phenomena, which could prove invaluable for future computational models predicting the behavior of polymeric flows in a reactive context.


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The work of Ueki et al. represents a pivotal step in the comprehensive understanding of polymeric reacting flows. The ability to predict and manipulate the flow behaviors of polymers post-reaction has broad and far-reaching consequences, potentially revolutionizing the methods and protocols employed across various scientific and industrial arenas.


The unpredictable dynamics of polymeric reacting flow, outlined by the research of Ueki and colleagues, demonstrate the complexities and surprises that await scientists delving into the molecular intricacies of fluid dynamics. This study not only provides valuable new insights into the behavior of reacting polymer flows but also sheds light on the utility of sophisticated diagnostic techniques like ATR-FTIR spectroscopy.


1. Polymeric Reacting Flow
2. ATR-FTIR Spectroscopy
3. Polymer Viscoelasticity
4. Molecular Diagnosis
5. Reactive Flow Dynamics

The pioneering work of this research team illustrates that the journey toward a full understanding of material science is replete with unexpected discoveries. It is through studies like these that the boundaries of knowledge are expanded, offering novel perspectives that challenge established notions in the fluid dynamics of polymers.