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Biopolymers: Making Materials Nature's Way

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Biopolymers: Making Materials Nature's Way Biopolymers: Making Materials Nature's Way September 1993 OTA-BP-E-102 NTIS order #PB94-107638 Recommended Citation: U.S. Congress, Office of Technology Assessment, Biopolymers: Making Materials Nature’s Way-Background Paper, OTA-BP-E-102 (Washington, DC: U.S. Government Printing Office, September 1993). Foreword ver the past century, global economic activities have increased more than fifty- fold. This extraordinary growth has raised serious concerns about current pat- terns of production and consumption. As society has increased its understanding of the environmental implications of its industrial practices, greater attention haso been given to the concept of sustainable economic systems that rely on renewable sources of energy and materials. The use of biologically derived polymers—biopoly - mers-could emerge as an important component of this new paradigm of economic development. By transforming agricultural or marine feedstocks, or harnessing the enzymes found in nature, a new class of renewable, biodegradable, and biocompatible materials is being introduced. Emerging applications of biopolymers range from packaging to indus- trial chemicals, to medical implant devices, to computer storage media. In addition to producing “green” materials with unique physicaI and functional properties, the process- es used to create biopolymers could lead to new manufacturing approaches that minimize energy consumption and waste generation. As the United States and other countries address a growing list of environmen- tal problems, the possibility of using proteins, carbohydrates, and other biopolymers to meet the materials requirements of an expanding economy is likely to receive increasing attention. However, as with other nascent technologies, difficult engineering and eco- nomic hurdles stand in the way of biopolymer commercialization efforts. With its current areas of emphasis, the extensive U.S. public investment in agricultural science and biotechnology can only be expected to provide modest assistance in overcoming some of these barriers. Advances in biopolymer technology have been driven principally by industry and academia, with Federal programs being relatively limited in scope. Because biopolymers have applications in many different sectors of the economy, their wide- spread use could have important competitive implications. At present, Japan and the European Community are sponsoring major programs in biopolymer science and manu- facturing. Due to the potential importance of biopolymer technology, the Federal role in this interdisciplinary field warrants closer scrutiny. This Background Paper was requested by the Senate Committee on Energy and Natural Resources. The study provides a basic introduction to biopolymer technology; profiles some of the more promising polymer materials; reviews research activities in the United States, Europe, and Japan; and describes the principal technical challenges and regulatory issues that may affect biopolymer commercialization efforts. OTA appreciates the assistance provided by its contractors and the many reviewers whose comments helped to ensure the accuracy of the study. Roger C. Herdman, Director .,. Ill Reviewers and Contributors G. Graham AlIan Dai Kim Julie Saad University of Washington Hiechst-Celanese Research Co. ICI America/Zeneca Bio Products Norbert Bikales Gretchen Kolsrud Steven Scale U.S. National Science Foundation U.S. Congress Tennessee Valley Authority Office of Technology Assessment James Brown Karen Shannon U.S. National Science Foundation Randolf Lewis Oblon, Spivak, McClelland, Maier, University of Wyoming and Neustadt, P.C. Robert Campbell U.S. Army Research Office Bernard Liebler Steven Sikes Health Industry Manufacturers University of South Alabama David Clements Association U.S. Department of Agriculture Kenneth Smith Congressional Research Service David Manyak National Sanitation Foundation Adheron Corp. Yoshiharu Doi Rodney Sobin Institute of Physical and Chemical Michael Marron U.S. Congress Research (RIKEN), Japan Office of Naval Research Office of Technology Assessment Greg Eyring Edward Mueller Graham Swift U.S. Congress U.S. Food and Drug Administration Rohm and Haas Co. Office of Technology Assessment Wolf-Rudiger Muller Ken Tracy Thomas Barrington Stuttgart University, Germany Warner-Lambert Co. Ashland Chemical Co. Ramani Narayan John Walker Joel Hirschorn Michigan Biotechnology Institute U.S. Environmental Protection Hirschorn & Associates, Inc. Agency D.A. Nicholson David Jensen Procter and Gamble Co. A.P. Wheeler U.S. Congress Clemson University Office of Technology Assessment Norman Oblon Oblon, Spivak, McClelland, Maier, David Kaplan and Neustadt, P.C. U.S. Army Research Development & Engineering Kevin O’Connor Center U.S. Congress Office of Technology Assessment NOTE: OTA appreciates and is grateful for the valuable assistance and thoughtful critiques provided by the reviewers and contributors. The reviewers and contributors do not, however, necessarily approve, disapprove, or endorse this background paper,OTA assumes full responsibility for the background paper and the accuracy of its contents. iv —- . —.—-—- .— Preject Staff Peter D. Blair Matthew Weinberg CONTRACTORS Assistant Director, OTA Project Director Oliver Peoples (beginning February 1993) Anthony Sinskey Industry, Commerce, Joe Raguso Bio Information Associates and International Analyst Boston, MA Security Division Energy and Materials Program ADMINISTRATIVE STAFF Florence Poillon Manager Editor (until August 1993) Lillian Chapman Office Administrator Lionel S. Johns Assistant Director, OTA Linda Long (until February 1993) Administrative Secretary Energy, Materials, and International Tina Aikens Security Division Secretary Emilia Govan Energy and Materials Program Manager (beginning August 1993) v contents 1 Introduction 1 Polymers: A Primer 4 Biopolymers 5 Impact of Genetic Engineering on Biopolymer Technology 8 The Role of Chemistry in Biopolymer Technology 12 The Policy Context 12 2 Technical Overview of Biopolymer Field 19 Selected Polymers Produced by Microbial Systems 19 Selected Polymers of Plants and Higher Organisms 35 Polymers Produced by Chemical Polymerization of Biological Starting Materials 43 3 Biopolymer Research and Development in Europe and Japan 51 Europe 51 Japan 59 4 Biopolymer Research and Development in the United States 67 Activities of the Federal Government 67 Private Sector Activities 73 vii — Introduction 1 hroughout history, humans have relied extensively on biological materials like wool, leather, silk, and cellu- lose.l Today, such natural polymers can be tailored to meet specific needs. The advent of modern biotechnol- ogyT has fundamentally transformed the way scientists view organisms and the materials they produce. For example, the genetic manipulation of some plant species could give rise to a new source of structural polymers that supplant traditional commodity plastics. By harnessing the enzymes found in nature, or transforming agricultural or marine feedstocks, a new class of biodegradable, biocompatible, and renewable materials is on the horizon. Polymers play a central role both in the natural world and in modern industrial economies. Some natural polymers, such as nucleic acids and proteins, carry and manipulate essential biological information, while other polymers such as the polysaccharides—nature’s family of sugars-provide fuel for cell activity and serve as structural elements in living systems. With advances in chemistry and materials science, a vast array of novel synthetic polymers has been introduced over the past century. Synthetic polymers such as nylon, polyethylene, and 1 These four materials are natural polymers. Polymers are substances composed of repeating structural units that are linked together to form long chains. 1 .——. 2 Biopolymers: Making Materials Nature’s Way polyurethane have transformed daily life.2 From precursors or are produced by using the methods automobile bodies to packaging, compact discs to of modern biotechnology.6 Such biopolymers clothing, and food additives to medicine, man- may prove to have a variety of environmental made polymers pervade virtually every aspect of benefits. Possible applications range from agri- modern society.3 culturally or bacterially derived thermoplastics However, the growing reliance on synthetic that are truly biodegradable, to novel medical polymers has raised a number of environmental materials that are biocompatible, to water treat- and human health concerns. Most plastic materi- ment compounds that prevent mineral buildup als, for instance, are not biodegradable and are and corrosion.7 However, because materials typi- 4 derived from nonrenewable resources. The very cally have many different properties, in certain properties of durability and strength that make applications biopolymers may not necessarily these materials so useful also ensure their persis- provide environmental advantages over conven- tence in the environment and complicate their 8 tional polymers. In practice, it is extremely disposal. In addition, the synthesis of some difficult to develop testing methods that assess polymeric materials involves the use of toxic 9 the environmental characteristics of materials. compounds or the generation of toxic bypro- ducts.5 In recent years, a number of significant techni- These problems have focused increased atten- cal developments, particularly in the area of tion on polymers that are derived from biological genetic engineering, have enhanced the commer- 2 These
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