Fundamentals of Polymer
1
Introduction
1.1
DEFINING POLYMERS
Polymers are materials of very high molecular weight that are found to have multifarious applications in our modern society. They usually consist of several structural units bound together by covalent bonds [1,2]. For example, polyethylene is a long-chain polymer and is represented by
ÀCH2 CH2 CH2 À
or
½ÀCH2 CH2 Àn
ð1:1:1Þ
where the structural (or repeat) unit is ÀCH2ÀCH2À and n represents the chain length of the polymer.
Polymers are obtained through the chemical reaction of small molecular compounds called monomers. For example, polyethylene in Eq. (1.1.1) is formed from the monomer ethylene. In order to form polymers, monomers either have reactive functional groups or double (or triple) bonds whose reaction provides the necessary linkages between repeat units. Polymeric materials usually have high strength, possess a glass transition temperature, exhibit rubber elasticity, and have high viscosity as melts and solutions.
In fact, exploitation of many of these unique properties has made polymers extremely useful to mankind. They are used extensively in food packaging, clothing, home furnishing, transportation, medical devices, information technology, and so forth. Natural fibers such as silk, wool, and cotton are polymers and
1
Copyright © 2003 Marcel Dekker, Inc.
2
Chapter 1
TABLE 1.1
Some Common Polymers
Commodity thermoplastics
Polyethylene
Polystyrene
Polypropylene
Polyvinyl chloride
Polymers in electronic applications
Polyacetylene
Poly(p-phenylene vinylene)
Polythiophene
Polyphenylene sulfide
Polyanilines
Biomedical applications
Polycarbonate (diphenyl carbonate)
Polymethyl methacrylate
Silicone polymers
Copyright © 2003 Marcel Dekker, Inc.
Introduction
3
Specialty polymers
Polyvinylidene chloride
Polyindene
Polyvinyl pyrrolidone
Coumarone polymer
have been used for thousands of years. Within this century, they
Introduction
1.1
DEFINING POLYMERS
Polymers are materials of very high molecular weight that are found to have multifarious applications in our modern society. They usually consist of several structural units bound together by covalent bonds [1,2]. For example, polyethylene is a long-chain polymer and is represented by
ÀCH2 CH2 CH2 À
or
½ÀCH2 CH2 Àn
ð1:1:1Þ
where the structural (or repeat) unit is ÀCH2ÀCH2À and n represents the chain length of the polymer.
Polymers are obtained through the chemical reaction of small molecular compounds called monomers. For example, polyethylene in Eq. (1.1.1) is formed from the monomer ethylene. In order to form polymers, monomers either have reactive functional groups or double (or triple) bonds whose reaction provides the necessary linkages between repeat units. Polymeric materials usually have high strength, possess a glass transition temperature, exhibit rubber elasticity, and have high viscosity as melts and solutions.
In fact, exploitation of many of these unique properties has made polymers extremely useful to mankind. They are used extensively in food packaging, clothing, home furnishing, transportation, medical devices, information technology, and so forth. Natural fibers such as silk, wool, and cotton are polymers and
1
Copyright © 2003 Marcel Dekker, Inc.
2
Chapter 1
TABLE 1.1
Some Common Polymers
Commodity thermoplastics
Polyethylene
Polystyrene
Polypropylene
Polyvinyl chloride
Polymers in electronic applications
Polyacetylene
Poly(p-phenylene vinylene)
Polythiophene
Polyphenylene sulfide
Polyanilines
Biomedical applications
Polycarbonate (diphenyl carbonate)
Polymethyl methacrylate
Silicone polymers
Copyright © 2003 Marcel Dekker, Inc.
Introduction
3
Specialty polymers
Polyvinylidene chloride
Polyindene
Polyvinyl pyrrolidone
Coumarone polymer
have been used for thousands of years. Within this century, they
References: Allen, G., and J. C. Bevington, Comprehensive Polymer Science, Pergamon, New York, 1989, Vols Kumar, A., and S. K. Gupta, Fundamentals of Polymer Science and Engineering, Tata McGraw-Hill, New Delhi, 1978. Tsuruta, T., Contemporary Topics in Polymeric Materials for Biomedical Applications, Adv. Polym. Sci., 126, 1–54, 1996. Barrett, K. E. J., Dispersion in Organic Media, Wiley, New York, 1982. Polym. Sci., 122, 55–124, 1995. Laszlo, P., Preparative Chemistry Using Supported Reagents, Academic Press, San Diego, CA, 1987. Hodge, P., and D. C. Sherrington, Polymer Supported Reactions in Organic Synthesis, Wiley, Chichester, 1980.