If Midwest farmers can grow corn to make ethanol, an alcohol fuel, why not harvest fields of soybeans, canola (Canadian rapeseed) and sunflowers to make the basic polymers for plastics, turning farms into "green" chemical factories?
After all, some biotechnology products once limited to laboratory petri dishes are being developed on farms with goats, pigs and sheep. So why not do the same with plants?That's some of the thinking behind Metabolix Inc., the Cambridge company that professor Anthony J. Sinskey of the Massachusetts Institute of Technology and two graduate students have formed to develop alternatives to petroleum- based polymers.
Polymers are substances composed of repeating structural units linked together to form long chains. Common synthetic polymers include nylon, polyethylene and polyurethane.
Lauded for their light weight and strength, such synthetic polymers are criticized by environmentalists. Not only are they not biodegradable, but they are derived from nonrenewable resources such as oil.
However, advances in genetic engineering have led scientists to some plant species that could be used to produce a new class of biodegradable polymers made from endlessly renewable resources such as cornfields.
There are seven types of biopolymer found in nature. Castor oil, for example, is already commercially used to produce a biopolymer known as "nylon 11." And coatings based on zein, the corn protein, have been used to replace wax-coated paper and paperboard coverings of food.
But as promising as biopolymer technology is, there are still some significant economic and engineering hurdles. For example commercially available biopolymers, a federal Office of Technology Assessment report said, are often two to five times more expensive than today's synthetic resins.
Scientists at the Cambridge company are working with one class of polymers, known as polyhydroxyalkanoates, that will be produced from bacteria in a laboratory to create products for the medical and specialty-chemicals industries.
Later Metabolix wants to genetically engineer the bacteria so that it can be grown in plants such as soybeans - and harvested as a biopolymer crop.