Polystyrene is a synthetic, petroleum-based polymer defined by long chains of styrene molecules. It exists in two primary forms: a clear, hard, and brittle solid plastic, and a lightweight, foamed version that is mostly air. The material’s low cost, durability, and insulating properties have made it ubiquitous in packaging, consumer goods, and construction.
The Initial Discovery of Polystyrene
The first isolation of the substance that would become polystyrene occurred in 1839 by German apothecary Eduard Simon. Simon distilled an oily substance from the resin of the sweetgum tree, which he named “styrol,” known today as styrene. After a few days, he observed that the styrol had thickened into a jelly-like substance, which he mistakenly believed was an oxidation product and dubbed “Styroloxyd.”
It took several decades for scientists to realize that the thickening was not oxidation but a process called polymerization, where the small styrene molecules linked together to form a long polymer chain. German chemist Hermann Staudinger later established the understanding of polymers as macromolecules in the 1920s, providing the theoretical foundation for the material’s potential and eventually leading to the name polystyrene.
Industrialization and the Birth of Mass Production
A significant gap existed between the 1839 discovery and the material’s commercial viability, as the polymerization process remained unstable and difficult to control. The breakthrough for mass-produced solid polystyrene came in the early 1930s, driven by the German chemical conglomerate I.G. Farben (including BASF). Scientists at I.G. Farben developed a reactor vessel that allowed for the controlled polymerization and extrusion of styrene into stable pellets. This marked the first time the material could be reliably manufactured as a solid plastic.
The new plastic was initially marketed as a potential replacement for die-cast metals like zinc, offering a lighter alternative. Polystyrene’s properties, such as its excellent electrical insulation and moldability, made it immediately useful in emerging technologies. Early applications included radio housings, battery casings, and electrical components. Following the German innovation, Dow Chemical introduced polystyrene to the U.S. market in 1937, cementing its status as an important industrial material.
The Rise of Expanded Polystyrene
The next major evolution was the development of its foamed version, Expanded Polystyrene (EPS), which occurred much later. This foam version required a separate technological leap involving the use of specialized blowing agents. German chemical engineer Fritz Stastny, working for BASF, developed pre-expanded polystyrene beads by incorporating aliphatic hydrocarbons, such as pentane, which acted as the foaming agent. The BASF patent for this process, which resulted in the product branded as Styropor, was issued in 1949.
The commercialization of the foam dramatically expanded polystyrene’s applications due to the new properties it offered. By trapping air within the material, EPS became extremely lightweight, a highly effective thermal insulator, and an excellent shock absorber. This led to its widespread adoption in packaging and in the construction industry for insulation in walls and roofs. Dow Chemical introduced a different type of extruded closed-cell foam in 1954 under the trademark Styrofoam, which further solidified the material’s presence in construction and packaging.
Modern Context and Environmental Considerations
Today, polystyrene remains a widely used material, manufactured in the millions of tons annually for applications ranging from disposable cutlery to sophisticated building insulation. Its low production cost and versatility continue to drive its use across numerous sectors worldwide. However, this popularity has brought the material into sharp focus within the modern environmental discussion.
Polystyrene is non-biodegradable and can persist in the environment for hundreds of years, contributing significantly to landfill accumulation and plastic pollution. When improperly disposed of, it easily breaks down into smaller fragments that become microplastics, posing a threat to marine and terrestrial ecosystems as wildlife can ingest the particles. The recycling process for polystyrene is complicated by its low density and high volume, which makes collection and transport economically challenging. As a result, many communities and businesses are exploring plant-based, compostable alternatives to mitigate the environmental impact of this long-lasting polymer.