What are Biodegradable Polymers?
Polymers are macromolecules consisting of repeated subunits called monomers. Polymers are either synthetic or natural. A few common examples of natural polymers are silk, wool, rubber, hemp etc and a few common examples of synthetic polymers are polyvinyl chloride, polypropylene, PVB, nylon etc. Synthetic polymers being highly durable, cheap and water-resistant can be easily produced and they have become an irreplaceable part of our daily lives.
Biodegradable and Non-Biodegradable Polymers
Polymers are widely used in our daily lives today. However, many polymers are highly resistant to degradation and are involved in the accumulation of polymer solid waste. These solid wastes as they continue to accumulate become a serious threat to the environment and remain undecomposed for a long period. As the use of polymers increases, the disposal of waste from these products also poses serious problems. These are Non-biodegradable polymers and the most common use of non-biodegradable polymers is plastics.
Due to these problems, scientists discovered Biodegradable polymers. Biodegradable polymers are easily degraded by microorganisms, resulting in less accumulation of waste and causing less harm and pollution to the environment such as aliphatic polyesters.
Biodegradable Polymers
Biodegradable polymers are the ones that get easily decomposed in nature by the aerobic and anaerobic processes. Biodegradable polymers can be put inside a bioactive environment, which allows them to undergo degradation with the enzymatic actions of microorganisms like fungi, algae, and bacteria. Non-enzymatic processes like chemical hydrolysis can also break down the chain of Biodegradable polymers.
Examples of Biodegradable Polymers
Poly β-hydroxybutyrate – co-β-hydroxy valerate (PHBV)
It is produced from the combination of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid, with monomer units connected by ester bonds. It decomposes into carbon dioxide and water. It is brittle and can be used to make medicines and bottles, orthopaedic devices, packing material etc.
Polyglycolic Acid (PGA)
Chain polymerization of cyclic dimers of glycolic acid produces Polyglycolic acid. It is the simplest linear aliphatic polymer used in drug delivery, orthopaedic operations such as screws and nails etc.
Nylon-2-Nylon-6
Nylon-2 Nylon-6 is an alternating polyamide copolymer made from glycine and aminocaproic acid and is used in making bristles of toothbrushes and strings of musical instruments.
Non-Biodegradable Polymers
Non-biodegradable items are composed of dangerous plastics, aluminium cans and bottles, scrap metal, foam styrol, tires, paints, and various chemicals. These objects are unaffected by natural processes and cannot be disassembled or degraded after thousands of years. They are highly toxic to the environment and contribute significantly to solid waste, which harms human health.
Examples of Non-Biodegradable Polymers
Polyethene
They are of three kinds namely-
Linear high-density polyethene (HDPE)
Branched low-density polyethene (LDPE)
Ultra-high molecular weight polyethylene(UHMWPE)
They have high strength and density and are used mostly everywhere.
Teflon
Teflon or tetrafluoroethylene is a synthetic fluoropolymer of tetrafluoroethylene which is less reactive and hence is used in cooking wares or wiring in aerospace etc.
Difference between Biodegradable and Non-biodegradable Polymers
Biodegradable Polymers
The biodegradables are non-resistant to natural degradation; thus, they quickly get decomposed in nature and do not create any waste material. Moreover, these polymers have small chains that help them break naturally in a short time.
The chains are hydrolytically or enzymatically cleaved, which results in the degradation of the products. This type of ability is mostly required in biomedical applications, where the polymer's degradation is a must to ensure the clearance from the body while eliminating the need for retrieval.
Some examples of biodegradable polymer applications are sustained drug delivery, tissue engineering scaffolds, and temporary prosthetic implants.
Non-Biodegradable Polymers
One of the most serious issues in recent years regarding these polymers is that we have tonnes of waste products floating in the ocean and dumped on land. These polymers are polyethene and polypropylene, which are made to be durable. This means that these polymers are hard to decompose, and they provide strength and durability to the products in which they are used.
In addition to this, plastics, which we see every day in our lives, are often soiled by food and other biological substances, making the physical recycling of these materials almost impossible to happen and generally undesirable.
More than 80% of the non-biodegradable plastic packaging is used only once, and then it is discarded.
Thus, it creates waste that is deposited in the oceans and on lands, affecting the natural balance of wildlife and nature. Indeed, these polymers bring lots of usability with them, but with nature and its protection in mind, we need to think about the decomposable alternatives and we should not create a mess while discarding them after use.
What are Biodegradable Polymers made from?
Plastics that can be broken down in the environment naturally are the answer to our pollution worries. There are several biodegradable polymers, and each of them can be classified into different properties using their chemical composition, origin, and method of synthesis. Most of the biodegradable materials come from plants such as soybean and corn. There are different biodegradation rates for other products. The third rate of biodegradation takes a longer time to decompose entirely in nature than the first-rate biodegradable polymers.
On the other hand, non-biodegradable polymers are made from different polyethylene, polypropylene, etc. These polymers react to the other chemicals to create stronger bonds, which give plastics different properties such as clarity, strength, stiffness, etc.
Types of Biodegradable Polymers
Biodegradable polymers are of three types. Some of them are synthetic-based, while some can be easily found in nature. Given below, we have shown different types of polymers, which are biodegradable. There are edible polymers as well.
Natural Biodegradable Polymers
They come from nature and are made from raw materials or renewable resources such as starch, cellulose, and lignin. Also, these polymers can be made using proteins like gelatin, casein, wool, and silk.
Polymers of the PHA Family
These polymers are made using genetically modified bacteria such as hydroxybutyrate, hydroxy valerate, polyhydroxy hexanoate, and hydroxy alkanoates.
Synthetic Biodegradable polymers
When a chemical polymerization occurs for the bio monomers like PLA, polycaprolactone, polybutylene succinate, and polybutylene succinate adipate, the product is found at the end of the chemical reaction are synthetic biodegradable polymers. They are not present in nature, but they can be easily dumped in nature after the reaction as they will break down and decompose.
FAQs on Biodegradable and Non-Biodegradable Polymers
1. What are biodegradable polymers? Please provide some examples from the CBSE syllabus.
Biodegradable polymers are materials that can be broken down into natural byproducts like carbon dioxide, water, and biomass through the action of microorganisms such as bacteria and fungi. According to the CBSE Class 12 syllabus for 2025-26, key examples include:
- PHBV (Poly-β-hydroxybutyrate-co-β-hydroxyvalerate): A copolymer used in specialised packaging and medical devices.
- Nylon 2–Nylon 6: An alternating polyamide copolymer.
- Polyglycolic acid (PGA) and Polylactic acid (PLA): Common polyesters used for surgical stitches.
2. What makes a polymer non-biodegradable? Give some common examples.
A polymer is non-biodegradable because its chemical structure consists of strong, stable bonds that are resistant to decomposition by environmental microorganisms. These polymers, like Polyethene (used in plastic bags) and Polyvinyl Chloride (PVC), have a backbone of strong carbon-carbon (C-C) single bonds that microbes lack the enzymes to break down effectively. As a result, they persist in the environment for hundreds or thousands of years. Other examples include Teflon and Polystyrene.
3. What is the main structural difference between biodegradable and non-biodegradable polymers?
The key structural difference lies in the type of chemical bonds present in the polymer's main chain.
- Biodegradable polymers, like aliphatic polyesters (e.g., PHBV), contain functional groups such as ester (-COO-) or amide (-CONH-) linkages. These bonds are susceptible to cleavage by microbial enzymes or hydrolysis, allowing the polymer to break down.
- Non-biodegradable polymers, like polyethene, primarily consist of a backbone of highly stable carbon-carbon (C-C) bonds, which are not easily attacked or broken by microorganisms.
4. Explain the composition of PHBV and why it is a biodegradable polymer.
PHBV stands for Poly-β-hydroxybutyrate-co-β-hydroxyvalerate. It is a copolymer formed by the polymerisation of two monomers: 3-hydroxybutanoic acid and 3-hydroxypentanoic acid. The monomers are joined by ester linkages. It is biodegradable because these ester linkages can be easily hydrolysed by enzymes produced by microorganisms, breaking the polymer down into smaller, naturally occurring molecules.
5. What are the monomers of Nylon 2–Nylon 6, and what makes it biodegradable?
Nylon 2–Nylon 6 is an alternating polyamide copolymer. Its monomers are:
- Glycine (which has 2 carbon atoms)
- Aminocaproic acid (which has 6 carbon atoms)
6. Why are biodegradable polymers crucial in medical applications like surgical stitches and drug delivery?
Biodegradable polymers are crucial in medicine because they can safely decompose and be absorbed by the human body over time. This property is vital for applications like:
- Surgical Stitches (Sutures): Polymers like Polyglycolic acid (PGA) dissolve naturally as the wound heals, eliminating the need for a second procedure to remove them.
- Drug Delivery Systems: The polymer can be used to create a capsule that slowly degrades, releasing a specific dose of medicine into the body over a controlled period.
- Orthopaedic Implants: Screws or plates made from these polymers can hold bones in place and then dissolve once the bone has healed.
7. If recycling exists, why is there a strong emphasis on developing biodegradable plastics?
While recycling is a vital part of waste management, it has limitations that biodegradable plastics can help overcome. Firstly, many plastic items, especially single-use food packaging, get contaminated with biological substances, making them unsuitable for physical recycling. Secondly, the process of collecting, sorting, and reprocessing plastics is energy-intensive and not always economically viable. Biodegradable polymers offer an alternative solution for products that are difficult to recycle, as they are designed to break down naturally in a bioactive environment, reducing long-term waste accumulation.
8. Are all naturally occurring polymers biodegradable?
No, this is a common misconception. While many natural polymers like starch and cellulose are readily biodegradable, not all are. The biodegradability of a polymer depends on its chemical structure, not its origin. For instance, natural rubber is a polymer that degrades very slowly in the environment. Conversely, many synthetic polymers like PHBV and PGA are specifically engineered with weak linkages (like ester bonds) to be fully biodegradable.
