You keep hearing about polyvinyl alcohol (PVA), sometimes hailed as the savior from all evils, sometimes branded as the devil? Why do some consider it plastic and others not? Don't worry, we'll try to sort things out by looking at what science tells us.

What is plastic?

Plastics are a broad class of materials that share the common characteristic of being composed of macromolecules, called polymers, which appear as long chains of repeating units, called monomers. If we imagine monomers as beads on a necklace, then the necklace is the polymer, and the characteristics of the "beads" used will determine the properties of the final material.

For 100 years we have been accustomed to dealing with plastics where the origin of these monomers was petrochemical and which brought with them a whole series of properties that have become inextricably linked to the concept of plastic for us: resistance, impermeability, non-biodegradability.

However, in recent years, new materials have been invented that challenge conventional wisdom and open up new facets to the definition of plastic, such as bioplastics (plastics whose monomers are of plant origin) and soluble and biodegradable plastics.

What is Polyvinyl Alcohol?

Polyvinyl alcohol is a synthetic polymer whose repeating unit is vinyl acetate. Unlike the plastic you're thinking of right now, thanks to its unique composition, PVA is transparent, odorless, has very low toxicity and high biocompatibility, is insoluble in organic solvents but... listen to this, soluble in water without leaving residue (the issue here is actually a bit more complicated, but we'll discuss it more here).

Precisely because of all these characteristics, PVA is used in a multitude of fields, first and foremost the health and medical ones, but also as a thickener, emulsifier, stabilizer and well, I won't list them all or it'll be too late.

So, is PVA plastic?

Now, the burning question: is PVA plastic? Technically yes, although it certainly does not have all those bad characteristics that we unconsciously associate with the concept of plastic. Unlike plastics such as polyethylene and polypropylene, PVA is in fact soluble in water, is completely and rapidly biodegradable in the right conditions [1] and non-bioaccumulative (i.e. it does not accumulate in organisms without being removed).

So is using PVA-based products safe for the planet?

The short answer is, it depends: it depends primarily on the type of PVA used (high or low polymerization) but above all on how the wastewater containing it is treated; modern wastewater treatment plants in our cities, however, have all the features needed to allow the PVA to dissolve completely, allowing it to be safely released into the environment.

[1] https://doi.org/10.1515/tsd-2020-2326

[2] doi : 10.1016/s0278-6915(02)00258-2