Which among the following is a biodegradable polymer?

PHBV

The correct answer is Option (4) → PHBV.

Let us examine the given options in detail:

1. PVC (Polyvinyl Chloride):

PVC is a synthetic polymer made by polymerizing vinyl chloride monomers (CH2=CHCl). It is a tough, rigid plastic widely used in construction (e.g., pipes, window frames) and packaging materials. PVC is not biodegradable. It is a stable, durable polymer that can persist in the environment for hundreds of years, contributing to pollution. It resists degradation by microorganisms and can only be broken down by heat or strong chemicals.

2. Freon:

Freon refers to a class of chlorofluorocarbons (CFCs), which are compounds made up of carbon, chlorine, and fluorine. Freons were widely used as refrigerants, propellants, and solvents. Freon is not biodegradable. It is chemically stable and contributes to environmental issues, notably the depletion of the ozone layer. It does not degrade naturally and requires complex chemical reactions in the upper atmosphere to break down.

3. Nylon:

Nylon is a synthetic polymer, specifically a type of polyamide. It is made by polymerizing hexamethylene diamine and adipic acid or caprolactam (in the case of Nylon-6). Nylon is used in textiles, engineering plastics, and various products like ropes, gears, and stockings. Nylon is not biodegradable. It resists microbial degradation and can persist in landfills or oceans for a long time. Nylon pollution, especially microplastics, is a significant environmental concern.

4. PHBV (Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)):

PHBV is a biopolymer that consists of two monomers, 3-hydroxybutyrate (HB) and 3-hydroxyvalerate (HV), produced by bacterial fermentation of sugars and lipids. PHBV is a biodegradable and biocompatible thermoplastic with properties like low toxicity, moderate flexibility, and good barrier properties. It is used in medical applications (e.g., sutures) and packaging. PHBV is biodegradable. Microorganisms in the environment, such as bacteria and fungi, can decompose it into water, carbon dioxide (or methane under anaerobic conditions), and biomass. This makes PHBV an eco-friendly alternative to traditional plastics.

Conclusion:

PVC, Freon, and Nylon are synthetic, non-biodegradable polymers that can cause long-term environmental pollution. PHBV is a biodegradable polymer produced by microbial action, making it a sustainable and environmentally friendly material. This is why PHBV is often used in applications where biodegradability is desired, such as biodegradable packaging and medical implants.