Cyclic olefin polymers are attractive high temperature polymers with outstanding optical properties, good chemical and heat resistance, and excellent dimensional stability. The three most important cyclo olefin monomers are norbornene, cyclopentadiene (CPD), and dicyclopentadiene (DCPD). The later two make up the largest portion in the C5 stream from steam cracked naphtha and account for about 15 to 25% of the total C5 fraction.
Cyclo alkydiene monomers can undergo a number of different types of polymerizations. One of the most widely used methods is ring-opening metathesis polymerization (ROMP). Using well-defined catalysts, ROMP allows for the control of the stereochemistry and molecular weight. Cationic and free radical polymerization is also possible which leads to saturated low molecular weight oligomers. These methods are less well known and have little to no commercial use. A third method is vinyl addition polymerization. In this case only the π-bond of the cyclolefin reacts whereas the bicycle structure remains intact. This type of polymerization yields high molecular weight polymers with good heat resistance, mechanical strength and high transparency.
Cyclic olefin copolymers (COC) find growing use as a shatter-resistant substitute for glass in optical lenses and films particularly in medical and electronic applications such as diagnostic tubes, touch screens (ITO film), light guides, and reflection films. Their excellent biocompatibility, chemical resistance and superior water vapor barrier also makes them a good choice for primary packaging of pharmaceuticals and for medical diagnostic disposables.