Polycarbonate, or PC, is a high-performance thermoplastic polymer widely recognized for its unique combination of strength and transparency. This material belongs to the family of engineered plastics and has had a profound influence on modern manufacturing and product design. Its origin involved a near-simultaneous invention that fundamentally changed the capabilities of plastic materials in the mid-20th century.
The Dual Discovery
The invention of polycarbonate is characterized by a remarkable and independent dual discovery that occurred in 1953 on two different continents. Dr. Hermann Schnell, a chemist working for Bayer AG in Germany, was the first to successfully synthesize the polymer in a commercially viable form. His groundbreaking work led to the filing of a patent for the first linear polycarbonate on October 16, 1953, at Bayer’s facility in Uerdingen.
Just a few days later in the same year, and completely unaware of Schnell’s achievement, Dr. Daniel Fox at General Electric (GE) in the United States independently synthesized a similar polymer. Fox, who was working in Schenectady, New York, was attempting to develop a new type of wire insulation when he discovered a gooey, clear substance that hardened into an incredibly tough material. This material resisted cracking and breaking despite his attempts to destroy it.
Both large chemical companies filed for U.S. patents in 1955, creating a complex legal situation over priority of invention. The patent priority was ultimately resolved in Bayer’s favor due to Schnell’s slightly earlier date of discovery. However, the companies reached a significant agreement that allowed both to operate: the patent holder would grant the other a license to the technology.
This arrangement permitted both Bayer and General Electric to proceed with commercial development. Dr. Schnell and Dr. Fox are therefore both acknowledged as the co-inventors who ushered in this new era of polymer technology. Their independent efforts confirmed the polymer’s potential and unique characteristics, setting it apart from existing plastics.
Chemical Identity and Defining Properties
Polycarbonate is a polymer that derives its name from the carbonate groups found repeatedly within its long molecular chains. Chemically, it is a condensation polymer typically synthesized through the reaction of bisphenol A (BPA) and phosgene, a highly reactive compound. This specific chemical structure, featuring rigid aromatic rings, gives the material its exceptional performance characteristics.
The most defining property of polycarbonate is its extreme impact resistance, which makes it virtually unbreakable compared to standard plastics or glass. This material can undergo large plastic deformations without cracking, a characteristic known as high ductility. It also possesses excellent optical clarity, allowing it to transmit light almost as well as traditional glass.
Polycarbonate exhibits high thermal stability, maintaining its physical properties across a wide temperature range. It has a glass transition temperature of approximately 147°C, meaning it can withstand high heat without deforming. This combination of toughness, transparency, and heat resistance set it apart from other polymers upon its introduction.
Commercialization and Market Adoption
Following the dual discovery, the race to bring polycarbonate from the lab to the marketplace was spearheaded by the two industrial giants. Bayer registered its polycarbonate product under the trade name Makrolon in 1955, and began industrial-scale production in Uerdingen, Germany, by 1958. This early commercial effort initially focused on applications in the electrical industry, such as telephone housings, due to the material’s insulating properties.
General Electric followed closely, launching its version of the material under the brand name Lexan, with commercial production beginning in 1960. The initial polycarbonate batches often had a slight brownish tint, but continuous refinement in manufacturing processes quickly led to a perfectly glass-clear material after 1970. The introduction of these two major brands, Makrolon and Lexan, quickly drove market adoption and established polycarbonate as a true engineering plastic.
The ability of both companies to manufacture and sell the material accelerated its entry into various industrial sectors. This allowed the polymer to be scaled for diverse industrial uses throughout the 1960s.
Ubiquitous Modern Applications
Polycarbonate’s unique properties have made it a nearly invisible part of daily life across countless products. Its exceptional optical clarity and strength made it the material of choice for spectacle lenses and safety eyewear, providing superior shatter resistance. The material’s durability and light weight are heavily utilized in the automotive industry for making headlight lenses and interior components.
The high impact resistance is also used in demanding security applications, such as transparent riot shields and bullet-resistant glazing for banks and government buildings. In the consumer electronics sector, polycarbonate is used for the durable housing of smartphones, laptops, and other electronic devices. The material also became the base substrate for all optical storage media, including compact discs, DVDs, and Blu-ray discs.
In construction, the polymer is used for lightweight, durable translucent structures like skylights and greenhouses. Polycarbonate continues to evolve, with new grades being developed to meet modern demands for sustainability and specialized performance.