This seems like it could be a viable replacement for many plastics, but it isn't the silver bullet I feel that the article is acting as if it is.
From the linked article in the post:
the new material is as strong as petroleum-based plastics but breaks down into its original components when exposed to salt.
Those components can then be further processed by naturally occurring bacteria, thereby avoiding generating microplastics
The plastic is non-toxic, non-flammable, and does not emit carbon dioxide, he added.
This is great. Good stuff. Wonderful.
From another article (this shows that this isn't as recent, too. This news was from many months ago)
the team was able to generate plastics that had varying hardnesses and tensile strengths, all comparable or better than conventional plastics.
Plastics like these can be used in 3D printing as well as medical or health-related applications.
Wide applications and uses, much better than a lot of other proposed solutions. Still good so far.
After dissolving the initial new plastic in salt water, they were able to recover 91% of the hexametaphosphate and 82% of the guanidinium as powders, indicating that recycling is easy and efficient.
Easy to recycle and reclaim material from. Great! Not perfect, but still pretty damn good.
In soil, sheets of the new plastic degraded completely over the course of 10 days, supplying the soil with phosphorous and nitrogen similar to a fertilizer.
You could compost these in your backyard. Who needs the local recycling pickup for plastics when you can just chuck it in a bin in the back? Still looking good.
using polysaccharides that form cross-linked salt bridges with guanidinium monomers.
Polysaccharides are literally carbohydrates found in food.
This is really good. Commonly found compound, easy to actually re-integrate back into the environment. But now the problems start. They don't specify much about the guanidinium monomers in their research in terms of which specific ones are used, so it's hard to say the exact implications, but...
...they appear to often be toxic, sometimes especially to marine life, soil quality, and plant growth, and have been used in medicine with mixed results as to their effectiveness and safety.
I'm a bit disappointed they didn't talk about this more in the articles, to be honest. It seems this would definitely be better than traditional plastic in terms of its ecological effects, but still much worse than not dumping it in the ocean at all. In my opinion, in practice it looks like this would simply make the recycling process much more efficient (as mentioned before, a 91% and 82% recovery rate for plastics is much better than the current average of less than 10%) while reducing the overall harm from plastic being dumped in the ocean, even if it's still not good enough to eliminate the harm altogether.