Polycyanurates

A new polymer type which emerged as important materials for circuit boards are polycyanurates. The simplest monomer is the dicyanate ester of bisphenol A. When polymerized, it forms three-dimensional, densly crosslinked structures through three-way cyanuric acid (2,4,6 triazinetriol):

The cyanurate ring is formed by the trimerization of the cyanate ester.

Other monomers, such as hexaflurobisphenol A and tetramethyl bisphenol F, are also used. These polymers are characterized by high glass transition temperatures ranging between 192 to >350°C.

The largest application of polycyanurates is in circuit boards. Their transparency to microwave and radar energy makes them useful for manufacturing the housing of radar antennas of military and reconnaissance planes. Their impact resistance makes them ideal for aircraft structures and engine pistons.