Scientists make plastic from a sugar and carbon dioxide | Hacker News Reader

Scientists make plastic from a sugar and carbon dioxide

bath.ac.uk

127 pointsphr4ts38 comments

Fun fact: cellulose (in wood) and chitin (in insect exoskeletons, fish scales, fungus cell-walls, etc.) are also polymers of glucose-derived sugars. Both are biodegradable, although humans can only digest the latter of the two.

Other fun fact: before the invention of entirely-synthetic plastics, we had phenolic sheets: layers of plain cellulose laminated together, originally using natural resin (tree sap), then later using synthetic resins, like Bakelite. These didn't have all the properties of synthetic plastics—you couldn't bend them, for example—but you could form them into shapes and introduce pigments, etc., while manufacturing. The earliest Printed Circuit Boards were Bakelite phenolic boards. (And even today, PCB insulator material is effectively a "synthetic phenolic board": it's fibre-reinforced plastic, which uses plastic itself in place of resin—and various synthetic fibres in place of cellulose—to achieve the same properties phenolic sheets have.)

Another feature of Bakelite is that after 60 years or so it tends to smell strongly, closely mimicking the smell of vomit. Hopefully any new formulations fare better.

> This new type of polycarbonate can be biodegraded back into carbon dioxide and sugar using enzymes from soil bacteria

This sounds amazing, but reading about various awesome breakthroughs has made me a bit cynical since there always is some sort of catch.

Does anyone know any limitations to this method which would make it difficult to scale?

If there are any, they'd probably be discussed in the actual papers and not here. I don't know if the UK is better, but at least in the US, university press releases about this or that research paper are usually garbage.

Does anyone have access to the actual papers?

    Georgina L. Gregory, Gabriele Kociok-Köhn and Antoine Buchard 
    “Polymers from sugars and CO2: ring-opening polymerisation and copolymerisation of cyclic carbonates derived from 2-deoxy-D-ribose” 
    DOI: 10.1039/C7PY00236J Polymer Chemistry, 2017, 8, 2093-2104

    Georgina L. Gregory, Elizabeth M. Hierons, Gabriele Kociok-Köhn, Ram I. Sharma and Antoine Buchard 
    “CO2-Driven stereochemical inversion of sugars to create thymidine-based polycarbonates by ring-opening polymerisation” 
    DOI: 10.1039/C7PY00118E Polymer Chemistry, 2017, 8, 1714-1721

    Georgina L. Gregory, Liliana M. Jenisch, Bethan Charles, Gabriele Kociok-Köhn, and Antoine Buchard 
    “Polymers from Sugars and CO2: Synthesis and Polymerization of a d-Mannose-Based Cyclic Carbonate” 
    DOI: 10.1021/acs.macromol.6b01492 Macromolecules, 2016, 49, 7165-7169

https://sci-hub.io/10.1039/C7PY00236J https://sci-hub.io/10.1039/C7PY00118E https://sci-hub.io/10.1021/acs.macromol.6b01492

They're on Sci-Hub, for the desperate. But, just glancing at them, they look legitimate. ACS especially doesn't accept low quality stuff (including some of my own work..)

If there are limitations to scaling, they'll probably not spell them out in the papers either. It's unfortunate, but "negative" aspects of one's own results are strongly suppressed in scientific publishing. And I'm not in any way pointing the finger at these particular authors, I'm pretty sure they're excellent scientists, it's just a problem in general.

I had a look around, and the papers aren't on any preprint servers etc. I guess we could violate copyrights, but a better solution might be that someone emails George and asks if she can get the preprints posted somewhere.

Edit: there's a preprint of the 2015 paper here: http://opus.bath.ac.uk/44557/

My guess? Energy usage.

One reason why crude oil, a fuel source, is also such a good chemical feedstock is that it contains a lot of complex, high-energy hydrocarbons. These are the kinds of complicated molecules that require a lot of energy input to form, and hence release lots of energy when burned. Reversing this process and turning simple carbohydrates plus carbon dioxide into complex carbohydrates is usually a highly endothermic reaction.

Which is why the use of the word "sustainable" here is suspect. Sustainable in that one day we will run out of oil? Yes. Sustainable in that the inputs do not exceed the outputs? That remains to be seen.

One limitation I see is the dependence on soil bacteria. We are already losing soil at alarming rate due to industrial farming. In the coming years it's going to be even more of a scarce resource.

The title of the article's pretty misleading. "sugar" means to most people either sucrose or glucose. Fructose, lactose, etc. could also qualify.

No, this uses a very obscure and expensive chemical called thymidine (most cost-effectively harvested from herring sperm, and primary precursor for anti-AIDS drug AZT). It may be "a sugar", but this article's playing fast and loose, akin to calling any pharmaceutical that ends with citrate or chloride "salt".

It also calls polycarbonate "scratch-resistant" when anybody who's worked with it knows it isn't. "Scratch-resistant coatings for phones, CDs and DVDs", really? CDs and DVDs are made of polycarbonate and they scratch easily.

Resistant is always a though word. The important, but hidden measurements are cost to produce, etc but relative to most other cheap, though, and clear materials...

CD's are actually very scratch resistant even though they often get lot's of small scratches.

> CD's are actually very scratch resistant even though they often get lot's of small scratches.

This is a bit of an oxymoronic sentence. How can something be both scratch resistant, while accumulating a large number of scratches?

The scratches a CD accumulates won't typically affect the ability to read from them, but that's due to the focal length of the reader, not the material.

https://en.wikipedia.org/wiki/Compact_disc#Integrity

Resistance is not immunity.

Bullet proof glass for example gets damaged by bullets. The trade off is always in how much damage and how quickly. CD's will easily survive with even moderate levels of care.

What people forget is the covering is really designed to protect the data layer not the surface. And in that context the clear plastic is actually better protection than the backside.

> What people forget is the covering is really designed to protect the data layer not the surface.

Right. But that this started explicitly about calling the polycarbonate -- that clear layer -- as scratch resistant. And this is just flat out wrong:

"Polycarbonate is a durable material. Although it has high impact-resistance, it has low scratch-resistance."

https://en.wikipedia.org/wiki/Polycarbonate#Properties_and_p...

I agree that it serves its purpose of protecting the data layer of the CD. But again, CDs and their readers were designed in a way that typical surface scratches and other imperfections would not inhibit reading. And so polycarbonate was an acceptable choice. The same approach applies to eye glass lenses; a scratch on a lens is typically not in focus and therefore has little to no effect on vision.

So, TL;DR: Polycarbonate the material is not scratch resistant. CDs are scratch resistant, but that is due to their optical design and in spite of the polycarbonate.

I don't directly disagree with what your saying, my point is there is more than one type of scratch resistance. Because not all scratches are created equal. If you look at say :https://omnexus.specialchem.com/polymer-properties/propertie...

You find it's good relative to other plastics at preventing penetration which is also why it's good at preventing deep scratches. So, yes if you want a crystal clear optical element then it's not scratch resistant and look for something high on the Mos scale. But, if you want a coating that protects from deeper scratches it's quite good. In that context it's good material to protect CD's from scratches that matter.

Which again is why I find the word resistance tricky because it's always resistant in some context.

Ah, I understand your point now. Thanks for clarifying for me.

It's a common confusion.

Poly-c is Lexan. It's amazingly impact-resistant, at least for a plastic. A window pane made of Lexan cannot be easily broken with a crowbar or a rock. But then people start attributing it characteristics that it doesn't really have, such as being scratch-resistant, which it clearly isn't.

It is synthesized in bulk.

At the time someone figured out AZT was a good AIDS drug it was sourced from herring sperm. But they got a chemical company to start producing it by the ton...

Even more misleading by including the photo of candy.

What is involved in the production of thymidine?

Even if the process did use conventional "sugar" the usual production source (corn syrup, sugar cane or beets) is not exactly environmentally friendly at scale.

Thymidine is one of the nucleosides in DNA, I'd hardly call that obscure. Not as easy and cheap to obtain as e.g. glucose or fructose, sure.

But the other two papers describe syntheses using mannose and ribose, so they did not use thymidine exclusively.

Ok, we'll spot you an indefinite article above.

Yep, from the title it almost looks like they are making a soda bottle from its content.

The graphic indicates that both the sugars and CO2 come from domestic waste. First extract with water, and then burn the residue. But it seems unlikely that domestic waste is such a great source of thymidine. And even if it were, the thymidine would mainly be part of DNA. So who knows?

There's a good side to that, since thymidine isn't a dietary sugar.

Should we use dietary sugars for any other end than human consumption, we will risk coupling the surge in that commodity 's price to food prices. Like biofuels - mass production of corn for biofuel at the current level of demand for fuels would probably mean, in the worst scenario, that popcorn would become prohibitively expensive.

There's 20+ pounds of corn in a gallon of ethanol. That gives popcorn quite a bit of runway (it isn't the same corn, but I guess the dollars/acre work out okay for popcorn).

Maybe popcorn was a bad example, but biofuels do drive food prices.

http://www.reuters.com/article/idUSN28615016

I read the headline and though "just what we need more plastic". I was pleasantly surprised to see that its biodegradable

The question is, under what degradation conditions (time, bacteria, etc), and what other threat vector does the material bring to animal life.

True, but biodegradable is still better than not.

Well no. Plastic biogrades at a snail's pace. Timescales differ on type of plastic. Plastic bags apparently take 20 years to biodegrade, for instance. PVC pipes are used in plumbing because biodegradation is extremely slow - not that it doesn't ever happen.

I wasn't aware that plastic bags / pipes biodegraded at all, hence my position.

I think plastics are one of those things where, dumped into a random place, they probably won't be biodegraded. However, for any given plastic, there is probably some organism in existence which will eat it under some or all conditions. So the usage of "biodegradable" maybe depends on which viewpoint you are interested in.

For example, here's the wiki on polyethylene, which seems like the typical plastic for "plastic bags" from a store:

https://en.wikipedia.org/wiki/Polyethylene#Biodegrading_plas...

The "bad plastic" is petroleum-based. Bad because it relies on fossil fuels, not compostable, etc. However there is a lot of science and research happening in natural plastics, that is plant-based plastics and others like this one. AKA bioplastics.

Sounds like this could also be really useful for future manufacturing industries on the surface of Mars or in the atmosphere of Venus. Polycarbonate also seems to have some resistance to sulfuric acid, which would be particularly useful in the Venusian atmosphere.

After extracting the sugar, many sugarcane mills burn the biomass (bagasse) for energy. So, they already have a free supply of CO2.

edit: Never mind, they are talking about another type of sugar.

Any details available on the processes involved?

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