New classes of polymeric materials with unique applications are being introduced. In many cases, the properties and their usage were discovered only recently. This chapter covers two areas: (1) health, medicine, and biotechnology, a rapidly developing domain based largely on known materials but moving to designed and engineered polymers, and (2) information and communications, an emerging field for polymers significantly based on their electronic properties. These two areas are attracting a great deal of attention, particularly among researchers who are not traditional specialists in polymer science. The growing importance of these fields makes the interdisciplinary aspect of polymer research abundantly clear.
Health, Medicine, and Biotechnology
Polymers play a major role in all aspects of biological processes. In fact, it is legitimate to proclaim that polymers are the molecular basis of life. The genetically inherited information required for the growth and health of living systems is encoded in the macromolecule deoxyribonucleic acid (DNA), the backbone of which forms the famous double helix. The molecular genetic code uses only four purine and pyrimidine bases to dictate the structure of the proteins that make up so much of living systems. DNA directs the assembly of about 20 amino acids in complex sequences that become the proteins. These proteins are polypeptide polymers that differ from one another only in the sequence of their constituent amino acids. All enzymes, which control the reaction rates in biological systems, are proteins. Collagen proteins form fibers and connective tissue found in tendons, cartilage, blood vessels, skin, and bone. Elastin, an elastic substance found in ligaments and in the walls of blood vessels, is also a protein. Other polymers such as polysaccharides are also important. They make up chains of sugar units present as a major constituent in all connective tissue. Ribonucleic acid (RNA) molecules also carry information and can serve protein-like functions. Thus informational, chemical, mechanical, and other properties of living systems find their origin in the molecular structure of their component polymers.
Medicine, as a biological science, therefore must be dependent on the nature of polymers. Bandages and dressings are dominated by polymers in modern practice. Molds and impressions of teeth, dentures and denture bases, adhesives, and fillings are polymer based. Sutures, which were made of cat gut for over 2,000 years, are now made of synthetic polymers. Hard and soft lenses required after cataract surgery, artificial corneas, and other ocular materials are all polymers.