Biodegradable vs non-biodegradable polymers

Biodegradable polymers

Biodegradable polymers are polymers that can be broken down by the action of microorganisms (bacteria, fungi) and enzymes in the environment into CO₂, water and biomass. They contain links such as ester or amide groups that enzymes can attack.

Examples: PHBV (poly-β-hydroxybutyrate-co-β-hydroxyvalerate; from 3-hydroxybutanoic and 3-hydroxypentanoic acids), polylactic acid (PLA), polycaprolactone, starch- and cellulose-based plastics, and nylon-2-nylon-6 (glycine + aminocaproic acid). Uses: packaging, carry bags, disposable cutlery, surgical sutures, implants, and controlled drug delivery capsules.

Non-biodegradable polymers

Non-biodegradable polymers are polymers that cannot be decomposed by microorganisms and stay in the environment for hundreds of years. Most have stable C–C backbones. Examples: polyethylene, polypropylene, PVC, polystyrene, PTFE, nylon 6,6, Bakelite.

Demerits

• Accumulate as solid waste in land, rivers and oceans, causing plastic pollution, choking drains (which leads to urban flooding) and harming animals that swallow them.
• Reduce soil fertility and block water seeping into the ground.
• Burning releases toxic gases (CO, dioxins, HCl from PVC, HCN) and CO₂.
• Break into microplastics that enter the food chain.
• Recycling is difficult and costly, especially for thermosetting plastics.