--- title: "Conducting and biodegradable polymers; applications" subject: "Engineering Chemistry" chapter: 4 key: "semester_2/engineering_chemistry:conducting-biodegradable" source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/conducting-biodegradable site: BCT Engineering --- # Conducting and biodegradable polymers; applications Engineering Chemistry · Chapter 4: Engineering Polymers - Asked in: 2067 Mangsir, 3 marks - Video: [Conducting Polymers - Polymers - Engineering Chemistry 1](https://www.youtube.com/watch?v=HE2zRQVhImw) — Ekeeda - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/conducting-biodegradable - Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-4 ## Question What are conducting and biodegradable polymers? Point out the applications of conducting polymers in engineering. ## Short answer Conducting polymers have conjugated backbones; doping creates charge carriers, raising conductivity. Engineering uses: batteries, OLEDs, sensors, EMI shielding and anti‑corrosion coatings. Biodegradable polymers like PHBV and PLA are broken down by microorganisms for packaging and medical sutures. ## Answer #### Conducting polymers **Conducting polymers** are organic polymers that conduct electricity. They have a conjugated backbone (alternating single and double bonds) with delocalised π electrons. When they are doped (oxidised with I₂ or AsF₅, or reduced with Na), charge carriers are created and the conductivity rises by many orders of magnitude. Examples: polyacetylene, polyaniline, polypyrrole, polythiophene. **Advantages** - Light in weight, flexible and low cost compared with metals. - Easily processed and moulded into films and fibres. - Conductivity can be tuned by doping. - Corrosion resistant. #### 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 usually 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. #### Applications of conducting polymers in engineering - Rechargeable lightweight batteries and supercapacitors. - Organic light-emitting diodes (OLEDs) and flexible displays, organic solar cells and transistors. - Antistatic coatings and EMI shielding for electronic devices. - Chemical sensors and biosensors, artificial muscles. - Anti-corrosion paints. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What structural feature allows a polymer to conduct? A. A conjugated backbone with delocalised pi electrons B. A saturated backbone of C–C single bonds C. A cross-linked sulphur network D. Many ester groups Answer: A. Alternating single and double bonds provide delocalised pi electrons. (Key point: Conducting structure) 2. What does doping do to a conducting polymer? A. Makes it biodegradable B. Creates charge carriers and raises conductivity by many orders of magnitude C. Cross-links it D. Reduces its conductivity Answer: B. Oxidising (I2, AsF5) or reducing (Na) agents produce charge carriers. (Key point: Doping) 3. Biodegradable polymers decompose into A. Pure metals B. Silica and ammonia C. CO2, water and biomass by microorganisms and enzymes D. Chlorine and carbon monoxide Answer: C. Microbial action converts them to harmless products. (Key point: Biodegradable) 4. Which is an engineering application of conducting polymers? A. Surgical sutures that dissolve B. Cooking utensils C. Pipes for drainage D. OLEDs, rechargeable batteries, sensors and anti-corrosion paints Answer: D. These applications exploit conductivity, light weight and flexibility. 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