Polymer
Introduction
A polymer is a large molecule, or macromolecule, composed of many repeated subunits, known as monomers. Due to their broad range of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function.
Structure and Properties
Polymers are studied in the fields of biophysics and macromolecular science, and polymer chemistry. A variety of other fields, such as materials science, biomedical engineering, and chemical engineering, are also deeply intertwined with polymer science. This is because the physical properties of polymers are unique and directly related to their atomic structure and molecular weight, which in turn influence their macroscopic physical properties.
Classification
Polymers can be classified in many ways, but one of the most common is based on their physical properties at high temperatures. There are two primary types: thermosetting polymers and thermoplastic polymers. Thermosetting polymers are rigid and cannot be melted and reshaped after they are cured, while thermoplastic polymers can be melted and reshaped multiple times.
Synthesis
The synthesis of polymers involves several distinct steps, including the initiation, propagation, and termination of the polymerization process. These steps are often catalyzed by chemical compounds known as polymerization catalysts. The specific catalyst and conditions used during synthesis can greatly affect the properties of the resulting polymer.
Applications
Polymers have a wide variety of applications that far exceed that of any other class of material available to man. Current applications extend from adhesives, coatings, foams, and packaging materials to textile and industrial fibers, composites, electronic devices, biomedical devices, optical devices, and precursors for many newly developed high-tech ceramics.
Environmental Impact
The environmental impact of polymers is significant due to their non-biodegradable nature. Many polymers, particularly those derived from petroleum, are resistant to degradation and can persist in the environment for centuries. This has led to widespread pollution, particularly in the world's oceans, where plastic waste accumulates in vast garbage patches.