Various scientists, engineers, and inventors can be credited with the discovery of natural polymers and the invention of synthetic polymers.
However, Hermann Staudinger was the first person to suggest polymers are composed of long chain molecules with repeating subunits held together by covalent bonds.
Polymers are chains of molecules that have repeating subunits known as monomers. Naturally occurring polymers serve as functional molecules for various life processes and as structural support, whereas synthetic polymers are used to manufacture manmade materials such as plastics.
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The origin of polymer science
For centuries, humans have been using natural polymers for various purposes, including weaving fabrics for clothing, making ropes, and constructing shelters. Despite this long history, polymer science is actually a relatively new field of study.
In the 1830s, scientists like Henri Braconnot and Christian Schönbein began to develop derivatives from cellulose. They were able to produce semi-synthetic polymer materials such as celluloid and cellulose acetate, which were commonly used in photographic films.
Then, in 1833, Jöns Jakob Berzelius coined the term “polymer”. Although he was unable to contribute any significant discovery in the advancement of polymer science, he at least gave it a name.
Important advancements in polymer synthesis were only possible following the independent discoveries made by Friedrich Ludersdorf and Nathaniel Hayward in the 1840s. They observed how adding sulphur to raw rubber stabilised the material and reduced its stickiness. Industrialists quickly capitalised on this scientific breakthrough and started to mass-produce commercial-grade rubber.
In 1843, Thomas Hancock received a UK patent for his method of vulcanising rubber by adding sulphur and subjecting it to heat. A few weeks later, Charles Goodyear received a separate patent in the US for the same process.
Further advancements in polymer science came in 1884 when Hilaire de Chardonnet developed a method for synthesising artificial fibre from plants by regenerating cellulose. He invented viscose rayon as a substitute for silk fabric.
Some decades later, in 1907, Leo Baekeland invented the first synthetic plastic. It was called Bakelite – a thermosetting phenol–formaldehyde resin.
Natural polymers and early uses
Examples of natural polymers that have economic value are cellulose, starch, and rubber.
These types of polymers are used to make various materials including clothing and tyres. For instance, cotton, which is one of the most commonly used materials for making threads and fabrics, is primarily composed of cellulose.
Hermann Staudinger
Despite the early advancements made in polymer synthesis, experts still didn’t understand how polymer molecules were formed and structured. It was Hermann Staudinger in 1922 who first proposed the idea that polymers are composed of long chains of atoms held together by covalent bonds.
However, his work on polymers wasn’t immediately recognised. It took more than a decade before it gained widespread acceptance in the scientific community. He was later awarded the Nobel Prize in Chemistry in 1953.
Before Staudinger’s discovery, scientists believed in Thomas Graham’s association theory, also known as aggregate theory. In 1861 Graham proposed that polymers like cellulose were actually colloids – aggregates of molecules with small molecular weights that were connected by a yet-to-be-discovered intermolecular force.
Breakthrough in synthetic polymers
Before synthetic polymers were invented, chemists and industrialists relied on existing natural polymers such as cellulose when creating new materials.
The breakthrough in synthetic polymers came when experts discovered how to connect monomers to form polymers. This discovery then made it possible to manufacture plastics and synthetic fibres.
Some of the most common types of plastic monomers include the following:
- Ethylene
- Propylene
- Styrene
- Phenol
- Formaldehyde resin
- Ethylene glycol
- Vinyl chloride
- Acetonitrile
Wallace Carothers and nylon
Nylon refers to a group of synthetic polymers derived from amide backbones, which are synthesised by linking aliphatic or semi-aromatic groups. The product was developed by the American chemist and inventor, Wallace Carothers, and a group of researchers in DuPont.
Their work, which was based on the theories of Hermann Staudinger, spanned an 11-year period between 1927 and 1938. Nylon’s physical properties can be modified by incorporating various additives.
Other synthetic polymers and inventors
Wallace Carothers wasn’t the only person to invent a synthetic polymer. Various other researchers discovered many of the modern synthetic polymers we use today, including polyethylene, polyester, Teflon, and Kevlar.
Polyethylene was first synthesised (accidentally) by German chemist Hans von Pechmann in 1898. Meanwhile, polyester was invented and patented by DuPont researchers led by W.H. Carothers in the 1930s. And Roy J. Plunkett accidentally invented Teflon in 1938 while working in the Jackson laboratory of DuPont.
Kevlar, a family of synthetic fibres with exceptional strength, was invented by Stephanie Kwolek in 1965. Although it’s probably most well-known for being used in bulletproof vests, the material has more than 200 different applications. These include materials for boats, aeroplanes, ropes, and cables.
Modern polymer science and technology
Modern polymer science and technology is focused on creating new materials and meta-materials with nano-components. These materials aren’t just limited to industrial applications such as plastics; they also have applications in medical science.
Biotextiles, for example, are used in precision medicine delivery as well as heart valves, grafts, hernia, and prolapse repair meshes.
While modern polymers are typically used as stand-alone materials, they can also be combined with other materials. High-performance engines and cars, for instance, are often constructed using composite polymer materials, as are prosthetic devices and artificial organs.
Conclusion
Advances in synthesising or deriving new materials from existing natural polymers were made as early as the 1830s. However, it wasn’t until 1922 that Hermann Staudinger realised polymers were chains of atoms or repeating units held together by covalent bonds. This understanding paved the way for the invention of new synthetic polymers and materials. Today, synthetic polymers have a wide range of industrial and medical applications.