GLOBAL CHALLENGES

Green Plastic Biodegrades Organically

R. Colin Johnson | Date: 03-24-10 | Comments

Organo-catalysis is a basis for a new era of green polymer chemistry whereby polymers are made biodegradable like natural materials. With such a technology, disposable water bottles, for instance, would be broken down into the basic monomers needed to reform them again into new polymer bottles, creating a sustainable cycle, according to researchers at IBM and Stanford University.

Plastics today, such as the popular polyethylene terephthalate (PET) used in disposable drinking bottles, are not generally reused in other drinking bottles but in a secondary plastic product such as packing material, which in turn eventually ends up in the landfill. Today, more than 13 billion plastic bottles are thrown away each year, and about 63 pounds of plastic for every man, woman, and child in the United States end up in landfills.

Jim Hedrick, a researcher at IBM�s Research facility in San Jose, Calif., works on new formulas to recycle plastic bottles for a new era of environmentally sustainable plastics. Source: Monica M. Davey, Feature Photo Service for IBM.

Green polymer chemistry changes all this by quickly breaking down plastic drinking bottles into basic monomers, which can then be easily reassembled into pristine new polymers that are again used for drinking bottles�thus forming a smarter sustainable model for plastic: reusing the same materials over and over. Organo-catalysis allows reuse of both common PET as well as plant-based plastics made from renewable sources in the environment.

"What we have done at IBM is develop a catalyst that can go into our material, and break it down very rapidly into the building blocks [monomers] that you can very easily build back up [into polymers],� explains Bob Allen of IBM Research. �It�s what we call a chemical recycling process."

IBM is also sponsoring researchers at the King Abdulaziz City for Science and Technology (KACST, Riyadh, Saudi Arabia) to develop the recycling process for a wide variety of PET-based plastics for food containers, beverages and other liquids. The goal is to develop a wide array of PET and plant-derived polymers that can create a 100 percent recyclable plastic economy for the consumer goods, health care and electronics industries. For instance, special biodegradable polymers could be delivered right to the site of a malady before breaking down and releasing their drugs. And electronic devices, such as security cards, could be designed to have a specific lifetime, before breaking down in an environmentally responsible way.

The main technique uses environmentally benign organic catalysts in place of conventional metal oxide or metal hydroxide catalysts in what is called a ring-opening polymerization process, which is used to produce almost any sort of PET container (the one with the "1" recycling label), supplemented by renewable polymers made from crop plants. The ultimate goal is to reduce the cost and efficiency of recycling plastics for primary uses so that it rivals the cost of disposing of the plastic in a landfill, thereby enabling a closed sustainable lifecycle for packaging in the future, whereby the same renewable materials are used over and over again.

The researchers are also developing higher-molecular-weight polyesters for a new generation of recyclable clothing made from sustainable, renewable resources.