Editorial pubs.acs.org/cm
Pioneers in Two-Dimensional Nanostructured Materials: Confinement of Ultrathin Polymer Layers New Members of Chemistry of Materials’ 1k Club: Giannelis, Ishii, and Vaia
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Who were the other authors on the paper, and at what stage were they? What are they doing now? EG: We were all starting our careers. Rich Vaia was a new graduate student, Hope Ishii was an undergraduate working in our lab, and I was a junior faculty member in the Department of Materials Science and Engineering at Cornell University. After Cornell, Rich has had a distinguished career as one of the technical leaders at the Air Force Research Laboratories.3,4 Similarly, Hope went on to receive a Ph.D. from Stanford and spent a decade at Lawrence Livermore National Lab, and she is now a Research Professor in Cosmochemistry at the University of Hawaii studying extraterrestrial materials.5 CM: Given the high citation record of this communication, a significant amount of research has been impacted by your findings over the years. Where did you think the field was headed? In your opinion, how has this particular research field evolved ever since? EG: We knew at the time that we were reporting a remarkable discovery but never imagined the impact the paper would have on the field. Let me explain. At the time when the paper appeared, the field of polymer nanocomposites had yet to be developed. In fact, the whole area of nanotechnology was just getting recognized as a new area of R&D. Up to that point it was well established that polymers intercalate between the clay layers but only from solution. In a serendipitous way we discovered that polymers could also intercalate from the melt, a scalable and green process that was completely unprecedented. In fact, some questioned our experiment, since it appeared to violate thermodynamics. CM: If you had to put your finger on it, what makes your paper special? What are you most happy about when you reread it? EG: Independently from our work and around the same time, a group at the Toyota Research Lab in Japan was demonstrating that small additions of clay could lead to significant improvements in mechanical, barrier, and thermal properties of many polymers. The demonstration from the Toyota group catalyzed a revolution in polymer research, since commodity polymers could be transformed into engineering plastics by adding fairly inexpensive fillers. The only catch was that the Toyota group had used solution polymerization for their nanocomposites. In contrast, our work established melt blending, a process available not only to the chemical industry but also to every converter in the plastics industry. We never of course imagined the impact the field of nanocomposites would have on so many research groups (both academic and industrial). When the paper appeared, clay nanocomposites was an up-and-coming field. The focus has been expanded from clays to include several other nanoparticle systems, including
urrently, two-dimensional nanomaterials are now an extremely popular area of research. Looking back to pioneers in any exciting area, one can pinpoint the early innovators who were typically interested in doing clever and curiosity-driven science, without any clear-cut or well-defined applications in mind. The latest members of our 1k Club, the authors of a paper that has been cited 1000 times or more, fit this description perfectly. In 1993, Prof. Emannuel Giannelis, then Ph.D. student Richard Vaia, and undergraduate Hope Ishii published a paper entitled “Synthesis and Properties of TwoDimensional Nanostructures by Direct Intercalation of Polymer Melts in Layered Silicates”.1 The paper has been cited more than 1500 times, thus far.2 The goals of the paper were pure and simple, to explore the new concept “that nanoscale materials would often exhibit physical and chemical properties that are dramatically different from their bulk counterparts”.1 Through a crafty and ingenious direct polymer melt approach, the authors produced very thin (3.2 nm thin) layers of polystyrene intercalated between silicate sheets, as shown schematically in Figure 1. When they tried using a solution of
Figure 1. Original figure from reference 1, showing the 3.2 nm thin, highly polymer nanosheets intercalated between layers of siicates. Reprinted with permission. Copyright 1993 American Chemical Society.
polymer as opposed to neat polymer, only solvent intercalation was observed. With respect to the resulting nanocomposites, they found that, when confined, the ultrathin polymer sheets did not undergo an expected glass phase transition, underlining their fundamental hypothesis that “nanosizing” would indeed induce different properties of the materials. We (Chemistry of Materials, CM) caught up with Prof. Giannelis (EG) to ask him more about their motivations and mindset at the time of doing the research. CM: At what stage of your academic career were you when you submitted this communication to Chemistry of Materials? © 2017 American Chemical Society
Published: May 9, 2017 3807
DOI: 10.1021/acs.chemmater.7b01646 Chem. Mater. 2017, 29, 3807−3808
Chemistry of Materials
Editorial
carbon nanotubes, graphene, and, more recently, other 2D materials as polymer reinforcements. Interestingly the “new” nanocomposites share the same challenges facing clay nanocomposites (dispersion, interfacial strength, fundamental understanding of property profiles). CM: What’s your advice to young scientists trying to discover the next breakthrough in material science? EG: Most important discoveries are serendipitous, and sometimes newcomers bring fresh ideas into a field. We also need to be open-minded to recognize the value and importance of experiments that do not support our hypothesis, since they can be groundbreaking and impactful.
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Carlos Toro, Managing Editor Jillian M. Buriak, Editor-in-Chief AUTHOR INFORMATION
ORCID
Jillian M. Buriak: 0000-0002-9567-4328 Notes
Views expressed in this editorial are those of the authors and not necessarily the views of the ACS.
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REFERENCES
(1) Vaia, R. A.; Ishii, H.; Giannelis, E. P. Synthesis and Properties of Two-dimensional Nanostructures by Direct Intercalation of Polymer Melts in Layered Silicates. Chem. Mater. 1993, 5, 1694−1696. (2) As per Google Scholar, reference 1 has been cited 1507 times as of April 21, 2017. (3) https://scholar.google.ca/citations?hl=en&user= K6kJnqEAAAAJ&view_op=list_works&sortby=pubdate. (4) http://science.dodlive.mil/2014/10/13/meet-the-scientist-drrichard-vaia/. (5) https://www.higp.hawaii.edu/cgi-bin/higp/directory.cgi?func= disp&searchname=HopeA.Ishii.
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DOI: 10.1021/acs.chemmater.7b01646 Chem. Mater. 2017, 29, 3807−3808
