From LCDs to medical materials

The influence of Liquid Crystal Displays (LCDs) on modern society has been dramatic. LCDs are now almost ubiquitous in electronic goods ranging from control instruments (eg thermostat controllers) to PC monitors and increasingly in large area high definition display devices. LCD sales revenues topped $100 billion in 2008 and are forecast to reach $150 billion by 2012.¹ However, the success of LCDs during the last decade has also led to a noticeable amount of LCDs entering in the waste electrical and electronic equipment (WEEE) waste stream. It is estimated that 2.5 billion LCDs are approaching their end of life and LCD WEEE is the fastest growing waste stream in the European Union. Legislative measures are in place to reduce the amount of electrical and electronic waste sent to landfill,¹ and the WEEE Directive 2002/96/EC of the European Parliament and of the Council on Waste Electrical and Electronic Equipment requires the disassembly of all LCDs with an area greater than 100 cm² and those containing mercury backlights.²

Today, an increasing number of LCD displays containing mercury backlights are entering the waste stream. Once the backlight has been removed a LCD is rendered 'safe' and may be sent for incineration or landfill,² but both these options waste resources and are potentially hazardous to the environment. In the UK alone it is predicted that over 10 000 metric tonnes of LCD will have been recycled in 2010. This equates to 9 tonnes of liquid crystals; 900 kg of indium and 8000 tonnes of optical quality glass that could be recovered but are currently being lost in landfill or incineration.¹ Although extraction of liquid crystals with volatile organic solvents such as dichloromethane offers a short term solution, using such highly toxic and potentially carcinogenic solvents is not a "sustainable" long term solution to the problem. Developing a holistic and environmentally acceptable strategy for the recovery and reuse of liquid crystals and other materials from LCD panels is key to successfully utilising this valuable waste stream.³ The development of new materials from waste electrical and electronic equipment (WEEE) is viewed as part of that strategy. Herein, we demonstrate that low value polymers from LCD can be recovered and transformed into materials with potential medical applications.