The LCGC Blog: Whence the Next Generation of Macromolecular Separations Scientists?

This blog is a collaboration between LCGC and the American Chemical Society Analytical Division Subdivision on Chromatography and Separations Chemistry.

A couple years ago I was interviewed by LCGC Europe on the topic of interaction polymer chromatography (1). In that interview I recalled how, during my time in industry, I developed an interactive gradient polymer elution chromatography (i-GPEC) method to determine the vinyl alcohol (VOH) distribution in the vinyl butyral terpolymer that comprises the middle, polymeric layer of most automotive and architectural safety glass (2,3). Applying this method during one of the “routine crises” that arise in industry, I was able to demonstrate that the undesirable behavior of a particular batch of polymer was due to its chemical composition distribution (CCD)—specifically, to the distribution in the percentage of VOH among terpolymer chains.

The type of i-GPEC method described above is not one that is developed “on the spot” and without a good fundamental knowledge of polymer chromatography. Fortunately, building upon expertise in this area I had already taken the time to painstakingly develop and perfect this and related methods so that, when needed, fine-tuning one of them to a particular application could be done relatively quickly. Waiting for a problem to manifest itself to then try and find an expert who can develop a non-trivial macromolecular separation is not the way to solve time-sensitive problems in industry. Moreover, development of new products or improvement upon existing ones relies strongly on macromolecular separations and an accompanying understanding of structure–property relations (3). It is of paramount importance that companies develop their in-house macromolecular separations expertise, not only polymer manufacturing companies but also those employing macromolecules for any of a host of applications, from drug-delivery and tablet coatings to ink-jet printer formulations and food additives, to name but a few.

A Lack of Qualified Candidates

Industrial managers and supervisors will recognize two immediate and related problems with my recommendation: First, they may not have any internal personnel in place with this type of knowledge who can further develop along these lines. Second, even if hiring is approved in this area, there is an almost complete lack of suitable candidates, even (actually, mostly) at the junior, entry-level stage. This leaves companies with three unappealing options: leaving an important characterization gap, hiring an unsuitable candidate who has only a cursory knowledge of the subject matter, or getting involved into a bidding war for the few senior-level experts still working in industry. Worse, there is currently virtually no refilling of the supply pipeline of chemists trained in this area.

Macromolecular Separations Require a Rarely Taught Skillset

Training in macromolecular separations involves much more than “just” being trained in chromatography. One must also be an expert, or at least have knowledge of several layers beyond the superficial, in polymer and colloid science (and biochemistry or carbohydrate chemistry, or both) as well as in certain aspects of physics, fluid mechanics, and so on. There are a number of reasons for this. For example, as part of a macromolecular separations experiment, one, will likely be dealing with light-scattering and viscometric measurements (among others) and interpretation of the results within the context of polymer science. As an example, one cares less about how much light is scattered by a polymer in solution upon irradiation by a light beam than about what this can tell us about the polymer’s molar mass and size, about the thermodynamic state of the solution, and more. In a general way, this is also true of any chromatographer: That person should have a decent knowledge of the intended analytes and of the detectors connected to the separation system. The additional challenge with macromolecular separations is the types of analytes studied, and the types of detectors most commonly employed, are not topics commonly taught in most chemistry departments. Polymers are usually given an at-best cursory look in most traditional organic and physical chemistry courses and detectors such as light-scattering photometers and differential viscometers are rarely mentioned in an instrumental analysis course.

More fundamentally, the types of separation methods employed in polymer characterization are not usually taught even in traditional separations courses, save for some brief mention of size-exclusion chromatography with, perhaps, a nod to field-flow fractionation. How many people who took a separations course learned anything about, for example, gradient polymer elution chromatography, temperature gradient interaction chromatography, or liquid chromatography at the critical condition, to name just a few macromolecular separations techniques? I bet the answer is “not many.” Without this fundamental knowledge of the separation methods, the detectors employed, and the analytes themselves, it is hopeless to expect an analyst to ascertain how changes in monomeric ratio or arrangement across the MMD of a copolymer translate into changes in the polymer’s rigidity, fractal dimension, solubility, and such. (4).

“It’s Déjà vu All Over Again” – Yogi Berra

Twenty-four years ago, chromatographer and industrial chemist extraordinaire Thomas Chester authored an article in the ACS Subdivision on Chromatography and Separations Chemistry (SCSC) Spring 1998 newsletter entitled “Supply and demand of chromatography knowledge in the workplace” (5). (Tom was, at that time, SCSC Chair; I thank him for kindly making a copy of his article re-available to me). Tom began his article by talking about the potential crisis in the supply of analytical chemistry PhDs that existed around 1980. He explained how this was dealt with, mostly by industry providing funding so that more analytical chemists would go into academia, where they could train the next generation of analytical chemists. He followed this with:

“Today we are facing a similar crisis. Chromatography, in its various forms, is by far the most often used analytical chemistry technique in industry. About half of the total effort of industrial analytical chemists is spent doing separations. The number of analytical chemists with research experience in chromatography doesn't come close to meeting the needs of industry. We see a lot of people filling these roles who might have been chromatography users in school but who did not perform chromatography research. Industry often values general problem-solving skills above any specific skill an employee may bring to the job. However industry is very shallow in real chromatography knowledge. Most comes from on-the-job training and short courses rather than personal instruction under the tutelage of a world-class expert. Too many workplace decisions are made empirically rather than with any notion of the underlying theory. And most users are helpless at doing anything new or different unless they can purchase the required knowledge from an outside source or find what they need in a catalog.

We simply don't have enough academic chromatographers. Without naming names, I can only count about a dozen world-class chromatography professors in the US. Most of these are older than 50, and there are only a couple under 40. Where will the next generation come from? How will their research be funded?”

Too Little Support for U.S. Academics in Separation Science

I think the concerns expressed by Tom in 1998 regarding chromatography, in general, remain true to this day and are even more pronounced in the case of macromolecular separations. How many “world-class” macromolecular separations professors can one find in the United States? Not users, but people who actually teach the techniques at a fundamental level and have developed a research program in this area? I can count but maybe a handful. (The situation is certainly better in, for example, The Netherlands, where a vigorous academic program in this area still exists and continues to thrive as part of a successful industrial-academic-governmental partnership).

Why is this? Certainly, one cannot imagine a polymer company not having in-house size-exclusion chromatography capabilities to determine, at the very least, the molar mass averages and molar mass distribution (MMD) of its products (how accurately this is being done is another question, one quite germane to our present discussion). Given that many industrial polymeric products are copolymers, complex polymers, or blends, there should naturally be an interest in other macromolecular properties such as the chemical composition distribution (CCD) and its co-dependence on molar mass, the so-called CCD × MMD of a macromolecule. I suspect the CCD is rarely determined for most products (as I did in the case described at the outset of this article), let alone the combined bivariate distribution. Again I ask, why is this? I believe the answer lies in the lack of experts in macromolecular separations, especially in academia, and in the concomitant vanishing pipeline of students being trained in this area.

I am heartened by a recent post in this blog by Michelle Kovarik, who made the case for incorporating the teaching of macromolecules and nanomaterials into separation science curricula and described how she and her colleagues at Trinity College (Hartford, Connecticut) have gone about doing so (6). This is most definitely a good beginning. Moreover, as a recent Nature career column decried, there is a need for universities to reward more than research outcomes and, in the process, to stop describing academic teaching as a “load,” with all that this term implies for a professor’s (especially an assistant professor’s) career (7). It shouldn’t be difficult for reasonable people to agree, however, that proper training in macromolecular separations can only be obtained by “immersion” (or, as Tom Chester put it, by “personal instruction under the tutelage of a world-class expert”), meaning, by having students trained in a graduate laboratory that specializes in the topic, in a program with one or more professors that teach courses and perform research in this and related areas. Over the course of four to five years in this type of program, sufficient practical and theory knowledge will have been gained so that newly minted PhDs can join the industrial workforce and make a near-immediate difference at their companies—or continue onto academia to train the following generation of experts.

Industry Needs to Support Academia

Developing this type of program in an academic setting requires support. It is industry that will reap the most benefit from having a workforce trained in macromolecular separations. It is industry that continually expresses to me the need for trained polymer chromatographers. Thus, it is industry that should make its needs strongly felt to funding bodies while simultaneously providing funding for professors, especially assistant professors just starting their academic careers, who are willing to perform research and train students in macromolecular separation science. Without this type of financial support, young faculty are sure to either leave academia or to take their programs in a different direction, one in which funding is being provided; either case will result in faculty no longer training students in macromolecular separation science. Will the lack of trained students be noticed? Probably not—at least not until the next “routine crisis” occurs at a company.

References

(1) A. Matheson, LCGC Europe 33(12), 614–616 (2020).

(2) A.M. Striegel, J. Chromatogr. A. 971(1–2), 151–158 (2002).

(3) A.M. Striegel, TrAC – Trends Anal Chem 130, 115990 (2020).

(4) S.M. Rowland, A.M. Striegel, Anal. Chem. 84, 4812-4820 (2012).

(5) T.L. Chester, SCSC Newsletter Spring (1998).

(6) M.L. Kovarik, LCGC Blog August 2 (2021) https://www.chromatographyonline.com/view/the-lcgc-blog-polymers-macromolecules-and-nanomaterials-in-the-separation-science-curriculum

(7) P. Copeland, Nature Career Column, January 27 (2022) https://doi.org/10.1038/d41586-022-00145-z

André M. Striegel

André M. Striegel obtained his bachelor’s and Ph.D. in chemistry from the University of New Orleans. He performed postdoctoral research at the USDA’s National Center for Agricultural Utilization Research and then worked for a number of years in the chemical industry, for Solutia Inc. (now Eastman Chemical). From industry he went on to Florida State University, where he was assistant professor of both analytical and materials chemistry. Since 2011, he has been at the National Institute of Standards and Technology (NIST), where he is currently Scientific Advisor in the Chemical Sciences Division. André is the author of over 90 peer-reviewed scientific publications, lead author of the second edition of “Modern size-exclusion liquid chromatography,” editor of the book “Multiple detection in size-exclusion chromatography,” past associate editor of the Encyclopedia of Analytical Chemistry and, since 2015, editor of Chromatographia. He has received a number of awards, including the inaugural ACS-DAC Award for Young Investigators in Separation Science, and was also inaugural Professor in Residence for Preservation Research and Testing at the US Library of Congress. His interests lie principally in the area of macromolecular separations, both fundamental and applied.

This blog is a collaboration between LCGC and the American Chemical Society Analytical DivisionSubdivision on Chromatography and Separations Chemistry (ACS AD SCSC). The goals of the subdivision include:

• promoting chromatography and separations chemistry
• organizing and sponsoring symposia on topics of interest to separations chemists
• developing activities to promote the growth of separations science
• increasing the professional status and the contacts between separations scientists

For more information about the subdivision, or to get involved, please visit https://acsanalytical.org/subdivisions/separations/.