polyphenylene

Polyphenylene is a term used for a class of aromatic polymers whose repeating units are based on benzene rings linked to form a hydrocarbon main chain. In many forms, the phenyl rings are connected in para positions, producing a rigid, rodlike backbone that contributes to high stiffness and thermal stability. The family includes poly(p-phenylene) as well as derivative polymers in which the inter-ring linkage includes heteroatoms or other bridging groups.

Common derivatives are polyphenylene oxide (PPO) and polyphenylene sulfide (PPS). PPO consists of phenylene rings linked through ether bridges, which improves processability while preserving high heat resistance. PPS contains sulfur bridges that further enhance chemical resistance and high-temperature performance.

Properties: Polyphenylene polymers typically exhibit high thermal stability, high modulus, and good chemical resistance. They are generally infusible and poorly soluble in ordinary solvents, making processing more challenging; some forms are processed as thermoplastic blends or through precursor routes.

Applications: PPO is widely used as an engineering plastic for electronics housings, connectors, and automotive parts due to dimensional stability and heat resistance. PPS is employed in demanding chemical environments, such as seals, pumps, valves, and electronic components, where chemical resistance and high temperature tolerance are required. Polyphenylene materials are also studied for applications in high-performance composites and electronic substrates.

See also: poly(p-phenylene); polyphenylene oxide; polyphenylene sulfide.