Novel plastic disintegrates in a week in sunlight and oxygen

Novel plastic disintegrates in...
A novel type of plastic developed by researchers in China can safely break down in a week in sunlight and air
A novel type of plastic developed by researchers in China can safely break down in a week in sunlight and air
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A novel type of plastic developed by researchers in China can safely break down in a week in sunlight and air
A novel type of plastic developed by researchers in China can safely break down in a week in sunlight and air

By making alterations to the plastic manufacturing process, scientists hope to produce forms of the ubiquitous material that can break down far more safely and quickly in the environment than current versions do. Researchers in China have now demonstrated a new example of this that degrades in just a week when exposed to sunlight and oxygen, which they believe could make for electronics that are easier to dispose of at the end of their lives.

The new material came about when study author Liang Luo from China's Huazhong University of Science and Technology was working on an advanced type of chemical sensor, as reported by PNAS. The materials scientist was developing a novel polymer film that changed color in response to pH levels. This process was driven by the material's unique molecular structure, with the chains of monomers giving the film its deep red color, and taking it away when these bonds were broken.

Through his team's experiments, Luo found that the deep red color of the film quickly faded away and the material broke apart after several days in the sunlight. Breaking apart these bonds is a common objective in research efforts to better recycle plastics, and in doing so Luo may have inadvertently conjured up a promising, environmentally friendly version of the material.

The molecular makeup of the plastic means it wouldn't be suited for use in soda bottles or shopping bags, as it is only stable as a functional material in the dark and without oxygen. But exposed to sunlight and air, it disintegrates rapidly and completely decomposes within a week, leaving no environmentally damaging microplastic fragments behind. A byproduct of the process is naturally occurring succinic acid, however, which could potentially be upcycled for commercial use in pharmaceuticals or food.

Where the plastic could find use, however, is in flexible electronics or smartphones, where it would be isolated from air and light during its service life. Luo imagines the material could last for years when used in this way, and then make these types of devices easier to dispose of after use. He plans to continue to explore the possibilities around these types of degradable plastics, but notes that commercialization is still years away.

The research was published in the Journal of the American Chemical Society.

Source: PNAS

We knew 20 years ago that adding starch to plastic got it to be broken down when buried or in open sunlit areas (natural) this "break through" sounds a lot more expensive.
Materials that are used in the dark are likely to be disposed of in a land fill. So, how long will this stuff last when buried with little oxygen and no light whatsoever?
In most cases, adding starch to plastic just meant that the starch broke down. All the microscopic remaining fragments of decomposition-resistant plastic, not so much.

I would be wary of anything that breaks down in response to stimuli that are generally available in the environment. Having the insides of your phone fall apart because you opened the case to change the battery outside a darkroom would be sad. The plastics that decompose in the presence of acids or digestive juices sound like a better plan to me.
Starch and plastic polymer prodegradent additives (such as oxo-degradable), aggravate the situation. They just turn an end-of-life problem you can see, into a problem you can no longer see (persistent micro-plastics). Even if the degradation process leaves no particles, the objective if we are to achieve circular economic goals, is to ensure that no resources are wasted. Years of sobering statistics demonstrate that conventional mechanical recycling of plastics, is severely limited and not a pathway to a circular plastics economy. However various chemical recycling technologies for plastics are in development and some in the early stages of commercialisation. Some of these are capable of taking any mixture of waste plastic and converting it to so-called Plastic Crude Oil, which becomes feedstock to re-produced virgin plastics. That cycle can be repeated limitlessly. Particularly if all energy inputs are renewable, the resulting plastics will then become environmentally benign.
breaks down into what?