The Structures and Cultures of the Disciplines: The Common Chemical Bond
Some Challenges for Chemists and Chemical Engineers
The first chapter of this report emphasizes the strong coupling and integration across the spectrum of chemical sciences and engineering. However, both chemistry and chemical engineering have traditional subdisciplines that define undergraduate education, graduate student training, and some aspects of the research agenda. The aims of these subdisciplines must be understood as part of the overall picture of the present and the future of our field.
In chemistry, standard subdivisions are analytical, biochemical, inorganic, organic, physical, and theoretical. The subdivisions in chemical engineering are: applied chemistry, kinetics and reaction engineering, process systems engineering, thermodynamics and chemical property estimation, and transport processes and separations. These subfield categories are primarily used for pedagogical clarity and organizational management in academia, but they are not typically used in industrial chemical research and development. However, the subfield limitations as artifacts and tools should be recognized—these categories are separated by boundaries that are neither essential nor rigid. This report has a central theme that creativity and progress often, perhaps even usually, occur across such boundaries. Thus as chemical science and technology move forward, it will be appropriate to examine whether the traditional disciplinary substructure continues to serve the chemical sciences well, or whether it is an impediment to progress. Chemistry, as a recognized discipline, is much older than the recognized field of chemical engineering with that name.1 However, this does not reflect the true history of the two fields. Humankind has been doing useful things with chemistry for a very long time—going back to ancient Egypt and even to prehistoric times— and applied chemistry is the ancestor of the modern discipline of chemical engineering.
Chemists seek to relate the properties of all substances, both natural and man-made, to their detailed chemical composition, including the atomic arrangements of all the chemical components. Chemists want to do this not only for existing substances but also for new substances that do not yet exist. For instance medicinal chemists make new substances as potential cures for disease. Understanding how the properties of substances are related to their molecular structures helps chemists and chemical engineers design new molecules that have the desired properties, allows them to develop or invent new types of transformations for carrying out the syntheses, and assists them as they design ways to manufacture and process the new substances.
Chemistry is still one of the natural sciences, but in a special and unusual way. Chemists want to understand not only the substances and transformations that occur in the natural world, but also those others that are permitted by natural laws. Consequently, the field involves both discovery and creation. Chemists want to discover the components of the chemical universe—from atoms and molecules to organized chemical systems such as materials, devices, living cells, and whole organisms—and they also want to understand how these components interact and change as a function of time. However, chemical scientists consider not just the components of the chemical universe that already exist; they also con-
sider the unknown molecules and substances and interactions that could exist. Thus there is a field of synthetic chemistry, in which new molecules and substances and chemical transformations are created, rather than discovered in nature.
New chemical compounds—consisting of new molecules—are being created at the rate of more than one million each year. However, the number of possible molecules that are reasonably small and simple—about the size of a typical medicinal agent and composed of the same few common elements—exceeds the number of known compounds by a factor of well over 1030. The chemical sciences produce tangible benefit to society when someone designs and engineers the production of a new and useful substance. Clearly, there is much to do in the creation and understanding of molecules that do not yet exist, and in developing the novel transformations that will be needed to make them.
Chemical scientists are concerned with the physical properties of substances. Are they solids, liquids, or gases? How much energy do they contain? They are also concerned with chemical properties. Can they be transformed to other substances on heating, or with light? Can they interact with other substances; for instance, can they dissolve in water, and why? Can they react with other substances to undergo a transformation to something new? Thus, the chemical sciences are concerned with substances, with their transformations, both chemical and physical, and with the design and control of processes to achieve these transformations on scales of practical commercial and beneficial value to society. Chemical scientists seek to fully understand the detailed mechanisms of these transformations, and to measure the rates of reactions, and to build predictive models of reaction sequences and networks for process design and control.
As part of the overall goal, chemical scientists also want to understand the biological properties of both natural and man-made substances. This includes not only learning the detailed molecular structures of all the substances in living things, but also understanding the transformations that go on in the life process. They want to understand these properties of pure substances, and they want to extend that understanding to organized systems of substances—including those as complex as a living cell, a whole living organism, and the complex multichemical system that is the earth itself. Chemical science is integral to all of bioengineering and biotechnology. Biosystems, from molecular assemblies to cells to organisms, require insight from synthetic and physical chemistry as well as analysis of complex chemical networks if they are to be understood and exploited for the benefit of society.
Investigating a single compound, a single reaction, or a single process may well fall within the expertise of a single discipline or subdiscipline, but the situation is different when the investigations are extended to systems—full assemblages of related components that address the same function—or to processes, where integrated systems of operations work in concert to produce a product. Understanding, developing, and manipulating systems and processes often re-
quire the synergistic advantages of the entire range of the chemical sciences— from fundamental chemistry, to chemical engineering, and even to other advanced areas of science and technology—to create scientific understanding and benefit for society. Chemical engineers have concerned themselves with design, scale-up, and construction of large chemical systems and processes. This requires mastery of chemical and physical transformations of matter. Chemical engineers bring quantitative, analytical, and computational tools to the design and development of chemical operations, systems, and processes. Chemical engineers have also made enormous contributions to fundamental science.
The evolution of chemical engineering as a distinct discipline within the chemical sciences occurred, largely over the course of the 20th century, through a series of leading paradigms. Chemical engineering emerged from applied chemistry by introducing an organized approach to the design of chemical process systems for manufacturing chemical products. The paradigm of unit operations— the individual steps of an overall process—characterized chemical engineering in the first half of the 20th century. During this time, the chemical industry, especially in the United States and Germany, was being built into a leading, and thriving, productive economic force with power and stability. Impressive success in this period was exemplified by the creation of a robust industry to produce polymeric materials in large volumes by the 1940s—when 15 years earlier the mere existence of such large molecules was being questioned on fundamental chemical grounds.
In the 1950s, and over the next roughly 30 years until the 1980s, chemical engineering research improved, advanced, and made more efficient both the design process and the ultimate designs of chemical plants. Similar progress was made in the understanding of chemical and physical transformations through applications of applied mathematics and computation. Academic research produced major advances in mathematical modeling and analysis—based on rapidly emerging new information on chemical kinetics, reaction mechanisms, and transport phenomena. This progress changed the process-design endeavor—from one based predominantly on empirical experience embodied in heuristics and correlations, to a more reliable, quantitatively predictive activity. The design of refineries and other facilities for production of large-volume commodity products was enormously influenced by predictive models based on science and applied mathematics. The abstraction necessary to produce general models for design purposes, as well as the maturing of chemical engineering as an academic discipline, had the effect of divorcing chemistry from chemical engineering to some extent, relative to the earlier period during which chemical engineering had emerged as a branch of chemistry.
The application of new methods for chemical research in industry during this period was reinforced by several factors. These included steady hiring of university graduates, the engagement of many university faculty members in the chemical sciences as consultants, the substantial growth of research divisions in many
companies doing long-range research, and the mutual understanding and alignment of goals between universities and industry.
All of these factors began to change in the 1990s. Fundamental chemical research began to overlap with and penetrate chemical engineering to an unprecedented extent. This has been characteristic for interdisciplinary fields such as polymers, catalysis, electronic materials synthesis and processing, biological science and engineering, pharmacology and drug delivery, nanoscale science and engineering, and computational science and engineering. These fields of research have become not just accepted but actually central to both chemistry and chemical engineering departments, and they cut across the traditional subdisciplinary boundaries discussed in the first paragraph. The nature of the efforts of chemists and chemical engineers in these areas are sometimes difficult to separate in a meaningful or useful way. Some research emphasizes fundamental curiosity or solving puzzles of nature, some aims to test intriguing or provocative hypotheses, and some seeks to improve our ability to address technological or societal problems.
There is no doubt that chemistry and chemical engineering have reached a high level of integration across the entire spectrum of the chemical sciences. Chemists—who have traditionally worked at the end of the spectrum nearest to pure, basic research—are also aware of the societal and technological benefit of their work. Indeed, such benefits are commonly cited to justify the costs of the research. Furthermore, chemists are increasingly involved in constructing, analyzing, and using complex systems and assemblies, from cells to clouds, from energy production to earth systems. This merges naturally with the systems approach of engineering. Approaching the chemical sciences from the traditionally chemical engineering end of the spectrum, we find chemical engineers increasingly entering, and in some cases leading, in more basic fields of chemistry because more science input is needed to solve technological problems or because the tools of the chemical engineer are more suited to discovery in certain areas. The evolution toward integration in the chemical sciences is quite consistent with the idea that they are gravitating toward Pasteur’s quadrant of Figure 1-1, in which the interplay between basic and applied research is more cyclical than linear.
A new kind of relationship is emerging between universities and industry in the chemical sciences, influenced in part by the Bayh-Dole Act of 1980, which allowed universities to retain intellectual property rights from federally funded research.2 As large industrial organizations have fewer and smaller departments doing long-range or basic research, they look to universities both for fundamental research and for students. In contrast to previous decades, in which many compa-
nies simply supported university research and teaching without looking for a specific return, current university-industry partnerships are often focused on specific shorter-term production of new data, knowledge, and insight. This has produced at least two identifiable trends in the nature of these relationships. In some cases, the interactions have become focused but strong—in terms of financial support of the academic partner from industry—enabling an unprecedented level of breadth and depth in concentration on subjects of mutual interest. In other cases, in order for university research to achieve technological or societal relevance, it has become necessary for university researchers to strike out on their own, to take promising leads from basic research and convert them into more fully developed technology. This means using research as a starting point and developing it into the seed of a start-up company. When large companies invest less in developing their own basic science, such start-up ventures become important in providing pathways that lead from discovery and invention to sources of new business development.
When taken together, the factors introduced in this chapter explain the motivation and rationale for this integrated report on challenges facing the chemical sciences, chemistry and chemical engineering. The chemical sciences will unlock our ability to understand the mysteries of our world—from new synthesis and catalysis to life itself. The chemical sciences will produce answers to our future energy needs and environmental challenges. The chemical sciences will produce the materials of the future, and they will produce practical biotechnology from biology. In this spirit, chemists and chemical engineers together are moving beyond the molecular frontier. The central challenge will be to create new understanding of our existing and potential physical world, and to use that understanding to produce a better world.