Colorado State University chemists were focused on making renewable and degradable plastics and other polymers to replace conventional petroleum-based materials. And they've made it - recyclable polymers, which can be transformed back into their original molecular states using heat. http://source.colostate.edu/recyclable-bioplastics-cooled-down-cooked-up-in-csu-chem-lab/ As far as I know, there were attempts in developing biodegradable/recyclable plastic before, but they weren't commercial success.
There are several plastics which are recyclable one which comes to my mind is acrylics . You heat them to a given temperature and it decomposes to a monomer that can be used .
http://science.opposingviews.com/biodegradable-plastics-made-soybean-products-22587.html I've just read an article about Habitat for Humanity constructing a house with a lot of soy by-products in it. Don't have the particulars, but it sounds promising.
Interestingly, and counter-intuitively, it may not be a good idea in any case. Read this for example: http://www.rsc.org/Education/Teachers/Resources/Inspirational/resources/6.1.2.pdf This is from the Royal Society of Chemistry, not an industry body with any commercial axe to grind. I suppose the question is what one is trying to achieve via biogradability. If it is to encourage the natural disappearance of discarded plastic litter, then biodegradation seems like a good option. But, if one is looking at how to deal with the huge amounts currently dumped in landfill, then it is not helpful, for the reasons given in the RSC briefing.
I don't see why we can't do both. Phase out the old style plastic production as we gradually replace those products with biodegradable ones. (Or learn to do without!) Recycle whatever petroleum based plastics we already have (I do anyway, and have since the 80's, when the service became available in my city. Actually, they were hoping for 20% compliance and had over 80% in the first month. People would be very much on board if they were convinced that it's on the level.) If we're not smart enough to co-ordinate this change-over, enlist a computer.
