Polyester is a synthetic material that has fundamentally reshaped the modern world, moving far beyond its origins in the laboratory to become a ubiquitous part of daily life. This versatile substance forms the basis of countless products, ranging from the clothing worn daily to the containers used for packaging beverages and food. Its remarkable properties, including durability, wrinkle resistance, and low moisture absorption, quickly established its importance in textiles and manufacturing globally. Understanding the story of this material requires looking back at the specific chemical breakthrough that brought it into existence.
Defining the Polyester Polymer
Polyester is the shortened name for a synthetic polymer, a large molecule composed of many repeating units, or monomers, linked together. Chemically, the term is a portmanteau of “poly,” meaning many, and “ester,” which is a specific functional group formed from the reaction of an alcohol and a carboxylic acid. The formation of polyester occurs through condensation polymerization, where small molecules join together to form a long chain, eliminating a small byproduct molecule, typically water.
The polymer must be formed from monomers that each contain two reactive functional groups, specifically a dicarboxylic acid and a diol (an alcohol with two hydroxyl groups). When these two monomer types react, they form a chain connected by ester linkages, the defining characteristic of this type of plastic. The most commercially significant polyester is Polyethylene Terephthalate.
The Crucial Precedent Set by Carothers
The initial work on creating synthetic polymers suitable for fibers began in the 1930s with American chemist Wallace Carothers at DuPont. Carothers pioneered the field of polymer science, successfully proving that polymers were long, high-molecular-weight macromolecules. His research focused on condensation polymerization, yielding the discovery of polyamides, which were commercialized as the first fully synthetic fiber.
Carothers and his team also experimented extensively with polyesters, noting that they could be drawn into fine threads. However, the polyesters they created were aliphatic, meaning they contained only straight carbon chains, which exhibited significant drawbacks for use in textiles. These early polyesters possessed low melting points and were easily dissolved by common dry-cleaning solvents. Because of these limitations, Carothers and DuPont abandoned the polyester line of research to concentrate on polyamides.
Whinfield and Dickson’s Breakthrough
The problem of creating a fiber-forming polyester with a high enough melting point was ultimately solved by two British chemists, John Rex Whinfield and James Tennant Dickson. Working at the Calico Printers’ Association (CPA) in Lancashire, England, they revisited the polyester concept. They realized that Carothers’ team had not fully explored the potential of using a specific aromatic acid in the polymerization process.
Their breakthrough came by reacting ethylene glycol with terephthalic acid, a dicarboxylic acid containing a rigid benzene ring structure. This aromatic component introduced stiffness into the polymer chain, which was the missing element needed to raise the melting point significantly. The resulting long-chain polymer was Polyethylene Terephthalate (PET), which possessed the necessary thermal stability and strength to be drawn into a viable, high-quality fiber.
The inventors successfully produced and patented the first linear aromatic polyester fiber in July 1941. Due to the ongoing Second World War, the patent was immediately classified under wartime secrecy restrictions. Consequently, the world did not learn of the full details of the invention until the patent was publicly released in 1946.
Global Commercialization
Following the public release of the patent, the process of commercializing the new fiber began almost immediately. Imperial Chemical Industries (ICI), a major British chemical company, acquired the patent rights for all territories outside the United States. ICI began manufacturing the fiber, marketing it under the trade name Terylene, and quickly established it as a competitor to existing synthetic fibers.
DuPont secured the licensing rights for the United States. They introduced their version of the Polyethylene Terephthalate fiber to the American market under a different trade name. The new polyester was rapidly adopted across the globe, especially in the post-war era, for its remarkable resilience and wrinkle-free properties. This led to its widespread use in clothing. Later, the same polymer structure was adapted for use in films and, famously, in the manufacture of lightweight, shatterproof plastic bottles.