Scientists at Stanford University (Stanford, California / USA; www.stanford.edu) and IBM Research (Yorktown Heights, New York / USA; www.research.ibm.com) have created a catalyst from common organic compounds to rival the standard, metal-based catalysts used in the manufacture of biodegradable plastics. While biodegradable plastics are kinder to the environment and a more sustainable alternative to their petroleum-based counterparts, the metal-based catalysts used to make them are difficult or expensive to remove from the final material, and do not degrade either.

In the alternative option, thiourea is reacted with a metal alkoxide resulting in a catalyst that is said to be both fast and selective. “While many catalysts are either fast or selective, these catalysts are both. They are simple to prepare, easy to use and can be readily adopted by anyone with a basic knowledge of chemistry,” said Robert Waymouth, a chemistry professor at Stanford and co-head of the research group.

He added that in addition to lowering the cost and environmental impact, the new catalyst design is highly tunable and can be used to generate several varieties of plastics, including polylactic acid, which is a biodegradable polyester used to make disposable tableware. Applications also exist in medical applications for resorbable sutures, implants and stents, as well as drug-delivery materials.

The researchers believe that because the technique is fairly simple and the catalysts are readily modified, their advances could lead to new and broadly useful classes of catalysts, and likewise new biodegradable plastics.

Xiangyi Zhang, a Stanford graduate student who conducted the experimental work, said the catalyst design could prove useful not only for polymerisation but for a wide range of organic reactions.