PLEXIGLAS® is one of the world's best-known plastics brands. But the material might never have been invented had it not been for an accident.
Major developments always require a certain degree of courage. Otto Röhm had this courage and the necessary determination at the beginning of the 20th century when he dedicated himself to plastics research and ultimately invented PLEXIGLAS® in 1933.
Courage to develop
Trained as an assistant pharmacist, Röhm (picture above; 1908) first studied Pharmacy and then Chemistry in Munich and Tübingen. In 1901 he earned his PhD with a dissertation on “Polymerization products of acrylic acid.” Six years later he and Otto Haas founded the Röhm & Haas company. Röhm was a true pioneer in the field of plastics, developing a large number of acrylate and methacrylate compounds. But the greatest invention by Röhm and his staff was the invention of PLEXIGLAS® in 1933.
This decision proved courageous as the previous focus of the Röhm & Haas activities had nothing to do with this field of research. The Röhm & Haas chemical company, founded in 1907, sold products for the leather and textile industry. In contrast, plastics research was extremely costly and at that time it offered little hope for commercial utilization.
But plastics research was always on Otto Röhm’s mind. In his dissertation on “Polymerization products of acrylic acid” (1901), he looked at the “fixed modification”, the acrylic acid ester polymerisate, a colorless, transparent, highly elastic and insoluble mass. Otto Röhm was convinced that commercially viable applications were possible with this material. He was absolutely determined to begin the search for suitable processes for producing acrylic acid ester and its potential applications. He named this field of research “rubber work”.
Research takes off
After World War I, the company was finally able to invest a greater amount of funds into plastics research. Röhm & Haas established a department dedicated to this research. But research was tiresome and costly – and explosions were a regular occurrence. At the same time, major companies such as I.G. Farbenindustrie AG put just as much effort into their plastics research. When compared to this strong competitor, it seemed that Röhm’s research department was understaffed and under-equipped.
The Röhm & Haas AG plant (1920)
After the first premises in Esslingen became too small, Otto Röhm established a new company site in the northwestern section of an industrial zone in the city of Darmstadt in 1909. PLEXIGLAS® still has one of its major sites in Darmstadt and in the neighboring town of Weiterstadt.
In 1927, the chemists developed the first successful plastics application: LUGLAS®. This is a shatterproof, laminated glass that was used for automobile windshields. It greatly reduced the number of severe cuts suffered during car accidents.
Röhm & Haas AG’s chemists achieved the big breakthrough in 1933 with the invention of the very versatile PLEXIGLAS® – a material is less likely to shatter despite being significantly lighter than glass.
“Polymerized” methly methacrylate (MMA) is poured between two glass panels that are enclosed by flexible sidebands. During the polymerization process in a water quench, the material shrinks slightly and the glass plates are drawn towards one another. The finished PLEXIGLAS® sheet can be easily removed from the glass plates.
The first plastics application: shatterproof LUGLAS
The Darmstadt-based researchers were still able to record their first success at the end of the 1920s: At that time, efforts were underway to discover ways for producing synthetic rubber, and Röhm, too, wanted to find a viable way towards acrylic rubber. Although he and his research team failed in these efforts, they were successful in developing LUGLAS, a safety glass for car windows, which also marked the entrance of the company into the acrylics business in 1928.
PLEXIGLAS® as the culmination of plastics research
In the 1930s, chemists around the world accelerated their efforts in plastics research at a breathtaking pace. It took just one decade for them to develop today’s most important plastics. And Röhm & Haas also continued their research efforts. After their success in the area of acrylates, they turned their attention to methacrylates. Here, Röhm and his team achieved a decisive breakthrough: The chemists discovered that polymethyl methacrylate (PMMA) was a harder, transparent material than the previously researched acrylates.
And an accident helped them along the way. A sample of the methyl methacrylate (MMA) monomer was stored in a bottle placed by a window. The polymerization reaction was triggered as daylight hit the bottle. This reaction destroyed the bottle and left behind a block made of polymethyl methacrylate (PMMA). During further experiments, the team was successful in polymerizing the raw material in a controlled manner between conventional glass panes thereby producing thin acrylic panels. The new material was named PLEXIGLAS and registered as a brand in 1933.
The PLEXIGLAS® name
The plastics researchers derived the name PLEXIGLAS® from the existing name PLEXIGUM, which designated the company’s plastics resins and solutions. Fascinated by the idea that they had used PMMA to create an “organic glass”, they named it PLEXIGLAS®. This marked the establishment of the “PLEX” as a superordinate brand name for products made by Röhm & Haas, and later Röhm.