Polymers for electrical and optical data storage

Polymers possess great significance in data storage technology. Taking as an example electrical and optical data storage, the state of development, properties required and opportunities for application of selected polymers are discussed, namely: (i) ferroelectric polymers with low switching voltages and extremely short switching times for electric data storage; and (ii) transparent polymers with low birefringence and high thermal stability for optical data storage. In the area of electrical data storage devices/memories, ferroelectric polymers have not been able to establish themselves up to now due to their long switching time and limited thermal stability. However, recent investigations show that suitable copolymers based on PVDF/TrFE copolymers in ultra-thin layers can achieve switching times of ≤100 ns. Nevertheless, the limited thermal stability of PVDF/TrFE copolymers prevent them from being integrated into the usual manufacturing process for Si-based data storage devices (D-RAM resp. S-RAM) and thereby frustrates the desired objective of producing nonvolatile random access memories (NV-RAMs). In the area of optical data storage technology, polycarbonate (PC) has established itself due to its favorable combination of properties. Thus, audio compact disks (CDs) are manufactured exclusively of PC, while high-flow PC types of high optical purity are clearly the preferred substrate material for optical data storage disks. The increasingly stringent requirements to be met in terms of lower birefringence and better thermal stability mean that the development of suitable modified or substituted polycarbonates is required. The development work being carried out worldwide in this area is reviewed here, and new suitable substituted polycarbonates with lower birefringence and significantly increased thermal stability up to glass temperatures of 238°C are presented. In addition, we deduce structure—property relationships for the above-mentioned structurally modified polycarbonates, specifically considering rotation potentials along the polymer backbone.