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Biodegradable Polymers – Definition, Preparation, Properties, Uses

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  • Last Updated : 22 Dec, 2021

A polymer is a molecule made up of numerous small molecules called monomers that are joined together to form a larger molecule. The word “polymer” is made up of two parts: “poly” which means “many,” and “mer” which means “unit.” This diagram illustrates how a polymer’s chemical makeup is made up of numerous smaller units (monomers) linked together to form a bigger molecule. Polymerization is a chemical reaction that bonds monomers together to form a polymer.

Biodegradable Polymers

Microorganisms destroy biodegradable polymers in a suitable amount of time, ensuring that biodegradable polymers and their degraded products have a low environmental impact. Enzyme-catalyzed processes break these polymers down into little segments, and microorganisms manufacture these enzymes.

Method of Preparing Biodegradable Polymers

One technique to make a biodegradable polymer is to add hydrolysable ester groups to the polymer chain. Ester groups may be inserted into the polymer if the following acetal is added to an alkene undergoing free radical polymerisation. These “weak connections” will be broken down by enzymes.

Examples of Biodegradable Polymers

Because the weak links inherent in aliphatic polyesters are vulnerable to enzyme-catalyzed hydrolysis, they constitute an important family of biodegradable polymers.

  • Poly-β-hydroxybutyrate-co-β-hydroxy valerate (PHBV): It’s a 3-hydroxybutanoic acid and 3-hydroxypentanoic acid copolymer with ester links joining the monomer units.

Properties of PHBV:

  • It is a biodegradable polymer that degrades in the environment due to bacterial action.
  • 3-hydroxybutanoic acid gives PHBV its stiffness, whereas 3-hydroxypentanoic acid gives it its flexibility.

Uses of PHBV:

  • For the manufacture of orthopaedic equipment
  • As a type of specialised packing material.
  • In the case of controlled drug release.
  • Polyglycolic Acid (PGA): The chain polymerization of a cyclic dimer of glycolic acid, HO-CH2COOH, yields polyglycolic.

  • Polylactic Acid (PLA): Polymerization of the cyclic dimer of lactic acid (HO-CH(CH3)COOH) yields polylactic acid.

  • Poly (ε-caprolactone) (PCL): The lactone of 6-hydroxy hexanoic acid is chain polymerized to produce it.

  • Nylon-2-Nylon-6: Nylon-2-Nylon-6 is a glycine (NH2CH2COOH) and aminocaproic acid (NH2-(CH2)5COOH) alternating polyamide copolymer.

Properties of Biodegradable Polymers

  1. Biodegradable polymers can maintain strong mechanical integrity until they are degraded.
  2. Degradation usually starts at the end-groups because biodegradable polymers have exceptionally strong carbon backbones that are difficult to crack.
  3. Non-toxic biodegradable polymers
  4. Biodegradable polymer degradation rates can be controlled.
  5. Biodegradable polymers also lack crystallinity, which inhibits access to end groups.
  6. Hydrophilic polymers are biodegradable polymers.

Advantages of Biodegradable Polymers

  • It is Easy to recycle biodegradable polymers: These polymers not only degrade more quickly when disposed, but they may also be easily recycled organically. Recycling bio-waste can be composted or used as a renewable energy source for biogas production, which helps to reduce landfill waste.
  • The amount of waste generated is reduced: Depending on the substance used to produce it and the method of disposal, biodegradable plastic degrades in a matter of months.
  • Reduction in carbon Emission: One of the most notable advantages of employing biodegradable polymers to make plastic bags instead of traditional plastic is the huge reduction in carbon emissions throughout the manufacturing process.
  • Greenhouse gas emissions are reduced: Greenhouse gas emissions are decreased when biodegradable polymers are utilised instead of traditional plastics.
  • Reduced use of petroleum: Oil is a necessary component in traditional polymer synthesis. It’s no wonder that petroleum hurts the environment when you consider the amount of trash generated during refining and even during the extraction of oil from the soil.
  • They consume less energy during their manufacture: Biodegradable plastics use less energy in the long term and do not require the reprocessing of fossil fuels to manufacture polymers, despite the higher initial investment.

Disadvantages of Biodegradable Polymers

  • To contain potentially toxic materials, landfills are designed to be moisture-free and airtight. Biodegradation is often slowed by these anaerobic conditions, which help to prevent harmful compounds from being released from landfills.
  • Biodegradable polymers are excessively expensive to produce.
  • They aren’t easy to come by.
  • Commingled Plastic recycling is not a good fit for biodegradable polymers.

Uses of Biodegradable Polymers

  1. These are used for stitches after surgery.
  2. Tissue ingrowth materials, controlled medication release systems, plasma replacements, and other medical items frequently incorporate biodegradable polymers.
  3. These are utilised in agricultural goods like seed coatings and films.
  4. These are also seen in fast-food packaging and personal hygiene items.
  5. To increase aeration and encourage plant growth, biodegradable polymers are utilised in and on the soil.
  6. Biodegradable polymers are employed in medication delivery because it is necessary for the drug to be released gradually rather than all at once, and for the pill to remain safe in the bottle until it is time to consume it.
  7. In gene therapy, biodegradable polymers are used.
  8. Biodegradable polymers are employed in medicinal agents such as anticancer, antipsychotic, and anti-inflammatory drugs in the biodegradable system.

Sample Questions

Question 1: What are the examples of biodegradable polymers?


 The examples of biodegradable polymers are Poly-β-hydroxybutyrate-co-β-hydroxy valerate (PHBV), Polyglycolic acid (PGA), Polylactic acid (PLA), Poly (ε-caprolactone) (PCL) and Nylon-2-Nylon-6.

Question 2: What is polylactic acid?


Polylactic acid is produced by polymerizing the cyclic dimer of lactic acid (HO-CH(CH3)COOH).

Question 3: What are the uses of Poly-β-hydroxybutyrate-co-β-hydroxy valerate?


The uses of Poly-β-hydroxybutyrate-co-β-hydroxy valerate are:

  1. For the production of orthopaedic devices
  2. As a unique form of packaging material.
  3. When it comes to controlled medication release, there are a few things to keep in mind.

Question 4: What is Poly ε-caprolactone?


To make it, the lactone of 6-hydroxy hexanoic acid is chain polymerized.

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