this post was submitted on 20 Oct 2023
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Plastic as a term only makes sense to not include biological polymers if we define it to only be man-made polymers. It's arbitrary semantics, so I find it's better to be inclusive to help show the chemical quirks than to be exclusive on arbitrary lines.
It's fine if you want to draw some conceptual comparisons between biological and synthetic polymers, but it's 100% not true that "plastics" as defined as synthetic, organic polymers (I.e. acrylics, silicones, polyesters, polyurethanes, halogenated plastics, thermosets, thermoplastics et al.) are the same on a chemical basis as most biological polymers.
Like... where are you drawing the line? Are proteins a plastic? Is starch plastic? Is DNA plastic? RNA? Clearly not, by multiple definitions (bioavailability, reactivity, structure and function, persistence in the environment, etc.). Even biological compounds closer to synthetic polymers (cellulose, chitin, etc.) are definitively different, even if they do have longer persistence, lower reactivity, etc. And bioplastics (like what people mean when they say biodegradable plastics) are heat-modified biological polymers. They don't come out of a living thing that way; they are fundamentally altered from their previous form.
I guess I just... disagree that the distinction is "arbitrary semantics"?
All of these types of plastic you're using as counterexamples are more distinct from each other than they are from biological polymers.
Plastics are a ridiculously diverse group of chemicals, not including naturally occurring polymers is anthropocentric and not always useful.
What, in your opinion, is the semantic difference between the words plastic and polymer?
What is your word of choice to distinguish between naturally occurring and lab-made polymers?
It depends on the context. Sometimes plastic is good for that, but in this case I don't believe that it is.
Plastic is not a rigorous term. When discussing specific plastics it's petty much always better to describe specifics, because plastics are too diverse of chemistry to do anything else.