2 - Fundamentals of polymers

Summary

In nanotechnology, polymers play a very important role as one of most often employed materials, especially in the fields of nanofibers and nanocomposites. Hundreds of polymers, including natural and synthetic polymers, have been fabricated into nanofibers and nanocomposites in the past 20 years. Thus a fundamental understanding of polymers, especially fiber-making polymers, is essential for people in various fields such as the biological, medical, electrical and material areas that are converging with nanotechnology.

Polymeric materials

The first polymers to be exploited were natural products such as wood, leather, cotton and grass for fiber, paper, construction, glues and other related materials. Then came the modified natural polymers. Cellulose nitrate was the one that first attained commercial importance for stiff collars and cuffs as celluloid in around 1885. Notably, cellulose nitrate was later used in Thomas Edison's motion picture film. Another early natural polymer material was Chardonnet's artificial silk, made by regenerating and spinning of cellulose nitrate solution, which eventually led to the viscose process that is still in use today. The first synthetic polymer was Bakelite, manufactured from 1910 onward for applications ranging from electrical appliances to phonograph records. Bakelite is a thermoset, that is, it does not flow after the completion of its synthesis. The first generation of synthetic thermoplastics (materials that could flow above their glass transition temperatures) are polyvinyl chloride (PVC), poly(styrene–stat–butadiene), polystyrene (PS), and polyamide 66 (PA66). Other breakthrough polymers include high modulus aromatic polyamides, known as Kevlar™, and a host of high temperature polymers. Table 2.1 lists some of the polymers currently often encountered.