{"id":31032,"date":"2015-12-11T07:35:41","date_gmt":"2015-12-11T06:35:41","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=31032"},"modified":"2015-12-11T13:43:42","modified_gmt":"2015-12-11T12:43:42","slug":"recyclable-bioplastics-cooled-down-cooked-up-in-csu-chem-lab","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/recyclable-bioplastics-cooled-down-cooked-up-in-csu-chem-lab\/","title":{"rendered":"Recyclable bioplastics cooled down, cooked up in CSU chem lab"},"content":{"rendered":"

\"pla870\"Compostable cutlery and other products made from the biomaterial PLA\u00a0are biodegradable, but not fully recyclable. In a recent paper, CSU researchers have reported\u00a0a breakthrough in\u00a0recyclable polymers, which can be transformed back into their original molecular states using heat. Their breakthrough could lead to truly recyclable plastics.<\/strong><\/p>\n

The textbooks and journals said it couldn\u2019t be done.<\/p>\n

But Colorado State University chemists have done it: They\u2019ve made a completely recyclable, biodegradable polymer, paving a potential new road to truly sustainable, petroleum-free plastics.<\/p>\n

\"Eugene-Chen-194x300\"
Eugene Chen<\/figcaption><\/figure>\n

The innovation is from the lab of Eugene Chen, professor of chemistry and recent recipient of the Presidential Green Chemistry Challenge award<\/a>. Publishing in Nature Chemistry<\/a> Nov. 23, Chen and postdoctoral fellow Miao Hong describe synthesizing a polyester that, when simply reheated for an hour, converts back to its original molecular state, ready for reuse.<\/p>\n

Recyclable, in the purest sense of the word.<\/p>\n

Their starting feedstock was a biorenewable monomer that textbooks and journal papers had declared non-polymerizable, or could not be bonded into large molecules \u2013 polymers \u2013 typically required for use as a material.<\/p>\n

Renewable plastics<\/h3>\n

Plastics are the most common type of manmade polymer, which is the chemical term for a long chain of repeating small molecules, or monomers. Plastics like polyethylene and polystyrene are king among synthetic polymers, and have come under fire for piling up in landfills. Chen\u2019s lab is focused on making renewable and degradable plastics and other polymers to replace conventional petroleum-based materials.<\/p>\n

\u201cMore than 200 pounds of synthetic polymers are consumed per person each year \u2013 plastics probably the most in terms of production volume. And most of these polymers are not biorenewable,\u201d Chen said. \u201cThe big drive now is to produce biorenewable and biodegradable polymers or plastics. That is, however, only one part of the solution, as biodegradable polymers are not necessarily recyclable, in terms of feedstock recycling.\u201d<\/p>\n

\"Miao-Hong2-194x300\"
Miao Hong<\/figcaption><\/figure>\n

There are several biodegradable plastics on the market today, chief among them a starch-based material made from polylactic acid, or PLA. Compostable cups, cutlery and packaging in dining halls are made from PLA. They\u2019re biodegradable, yes, but they\u2019re not truly recyclable \u2013 once made, they can\u2019t be completely reconstituted into their original monomeric states without forming other, unwanted byproducts.<\/p>\n

And what about those little numbers on the bottoms of plastic containers? Doesn\u2019t that mean \u201crecyclable\u201d? Sort of. Soda bottles, computer keyboards and millions of other plastics can be repurposed to extend their product lifecycle. But in the true, chemical sense of \u201crecyclability\u201d \u2013 biomolecules that can be synthesized into a useful material, and then completely converted back to the same molecules simply by heating the bulk material \u2013 is unheard of. Until now.<\/p>\n

\u2018Don\u2019t even bother with this monomer\u2019<\/h3>\n

The researchers\u2019 starting monomer is a mouthful for being such a small molecule: Gamma-butyrolactone, or GBL. It is a colorless liquid and common chemical reagent, derived from a top-12 biomass compound best suited to replace petrochemicals, according to the Department of Energy.<\/p>\n

\"chen_graphic-212x300\"
A graphical illustration of the researchers\u2019 polymer synthesis process. The single molecules, or monomers, are cooled in order to polymerize; to cycle back, heat is applied. Credit: Jing Tang\/Chen lab<\/figcaption><\/figure>\n

Textbooks and scientific literature had described these small molecules as too happy and thermally stable in their monomeric chemical states to polymerize.<\/p>\n

\u201c\u2019Don\u2019t even bother with this monomer,\u2019\u201d Chen summarized the conventional wisdom. \u201c\u2018You cannot make a polymer out of it because the measured reaction thermodynamics told you so.\u2019 We suspected that some of the previous reports were probably incorrect.\u201d<\/p>\n

Not only did they make a polymer, Chen and Hong figured out how to get the polymers to take different shapes, such as linear or cyclic, based on the catalysts and conditions they selected. For their experiments, they used both metal-based and metal-free catalysts to synthesize the polymer, called poly(GBL), which is chemically equivalent to a commercial biomaterial called poly(4-hydroxybutyrate), or P4<\/sub>HB.<\/p>\n

Precise reaction conditions<\/h3>\n

They employed specifically designed reaction conditions, including low temperature, to make the polymer, and heat between 220-300 degrees Celsius to convert the polymer back into the original monomer, demonstrating the thermal recyclability of the polymer.<\/p>\n

P4HB is derived from bacteria, which is a more expensive, complex process than how most plastics are made. By starting with the readily available GBL and ending up with a replacement material for P4HB, Chen\u2019s discovery has promising market potential, and a provisional patent has been filed with the help of CSU Ventures.<\/p>\n

\u201cIn my 15 years at CSU, I would probably call this my group\u2019s most exciting piece of work,\u201d Chen said. \u201cThis work creates a class of truly sustainable biopolymers, as they are both biorenewable and recyclable, based on a bioderived monomer previously declared non-polymerizable.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

Compostable cutlery and other products made from the biomaterial PLA\u00a0are biodegradable, but not fully recyclable. In a recent paper, CSU researchers have reported\u00a0a breakthrough in\u00a0recyclable polymers, which can be transformed back into their original molecular states using heat. Their breakthrough could lead to truly recyclable plastics. The textbooks and journals said it couldn\u2019t be done. […]<\/p>\n","protected":false},"author":59,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","nova_meta_subtitle":"","footnotes":""},"categories":[5572],"tags":[5847,5885],"supplier":[3135,6678],"class_list":["post-31032","post","type-post","status-publish","format-standard","hentry","category-bio-based","tag-bioplastics","tag-pla","supplier-colorado-state-university","supplier-nature-chemistry"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/31032","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=31032"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/31032\/revisions"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=31032"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=31032"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=31032"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=31032"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}