Given how ubiquitous polymers are in our lives today, it’s rather incredible to think that the concept of a polymer did not exist until relatively recently. People used to think that polymer materials were actually colloids – they described the material properties they observed by saying that there were “lots of small molecules that were interacting strongly with each other”. If you told scientists 100 years ago that there were actually really long, huge, molecules in there that were strung together with covalent bonds, they would have said you were crazy. The concept of such “macro molecules” just did not exist. So even though people have been using polymers for millennia (wood, silk etc.) and even more recently (do you know those really old telephones made of Bakelite?) – the concept of a polymer did not exist until Staudinger came along in the 1920s – it’s that recent! So it also just goes to show you that a lot of materials science, in terms of applications – you can get pretty far sometimes without understanding the fundamentals, but once people understood polymers on a molecular level, both research and applications exploded.
As stated previously, natural polymers have been used for ages – wood and cotton, for example, are made of natural polymer. But the earliest examples of actual polymer chemistry really start in the 1830s, when people began experimenting with reactions of cotton – cotton, of course, being cellulose. This work led to the discovery of various nitrated cellulose products. Nitrocellulose, also called Celluloid, was used as an early replacement material for billiard balls. At the time, billiard balls were made from elephant ivory, and it was getting really expensive (and environmentally unsustainable), so there was a push to find a suitable substitute. The problem was that the “sound” billiard balls made when they hit each other was really important, and difficult to replicate in other materials. John Wesley Hyatt used one of these modified cellulose polymers to create billiard balls, and it was quite successful! However, there was a slight problem with nitrated cellulose polymers in that there were quite flammable and legend has it that occasionally the billiard balls exploded! So clearly, more work needed to be done. Along came Bakelite – which is the first example of a truly synthetic polymer (the rest were just modifications of cellulose). Bakelite, formed from the condensation reaction of phenol with formaldehyde, became hugely popular – perhaps you have seen products with Bakelite, such as those old telephones. Keep in mind that all this time, people still didn’t really know what a polymer was.
Hermann Staudinger was the first to suggest in 1920 that a polymer is actually a very large molecule, a macromolecule, where the atoms in the molecule were held together by covalent bonds. Recall from general chemistry that a covalent bond is made when atoms share their electrons – this is distinct from a simple attraction between molecules, which is what up until this point, was what everyone thought was what was giving these materials their unique properties. The general consensus was that the materials were simply colloids, where the particles were small molecules held together by attractive intermolecular forces. So this idea that there was actually a giant molecule in there was at the time incomprehensible. It took over a decade for Staudinger’s ideas to fully catch on, and he received the Nobel Prize for his contributions in 1953.
There have been lots of amazing discoveries about polymers since then. For example, even more recently, conductive polymers were discovered – again, at the time, it was difficult for people to believe that an organic material like a polymer could be conductive like a metal, but it's true! Polymers have found even more uses than you could imagine. They are replacing traditional metals and semiconductors, they are being used in solar cells and electronics. There are polymer formulations that are being used in composites for building materials, medicine, drug delivery, adhesives, paints, packaging, clothing. Everywhere.