Introduction and classification of polymers MCQs With Answer

Introduction and classification of polymers MCQs With Answer helps M. Pharm students solidify core concepts from Drug Delivery Systems (MPH 102T). This quiz set focuses on polymer basics—definitions, origin and structural classifications, polymerization mechanisms, molecular weight averages, thermal transitions, crystallinity, and functional categories relevant to dosage forms. You will test your understanding of biodegradable versus bioerodible behavior, surface vs bulk erosion, hydrogels, copolymer architectures, mucoadhesion, and stimuli-responsive systems. Examples commonly used in pharmaceutics—PLGA, PEG, chitosan, HPMC, poloxamers, alginate, and polyanhydrides—are embedded to connect theory with practice. Use these MCQs to assess readiness for exams and to guide deeper study into polymer selection for safe, effective drug delivery.

Q1. Which statement best distinguishes addition (chain-growth) from condensation (step-growth) polymerization?

• In addition polymerization, monomers add to an active center without byproducts; in condensation polymerization, functional groups react with elimination of small molecules.
• Both mechanisms require elimination of small molecules for propagation.
• Condensation polymerization rapidly yields very high molar mass at low conversion, whereas addition polymerization requires near-complete conversion.
• Addition polymerization always proceeds via stepwise reactions of functional groups without active centers.

Correct Answer: In addition polymerization, monomers add to an active center without byproducts; in condensation polymerization, functional groups react with elimination of small molecules.

Q2. Classify the following by origin: Chitosan, HPMC, PLGA.

• Chitosan—natural; HPMC—semi-synthetic; PLGA—synthetic
• Chitosan—semi-synthetic; HPMC—natural; PLGA—synthetic
• Chitosan—synthetic; HPMC—semi-synthetic; PLGA—natural
• All three are synthetic

Correct Answer: Chitosan—natural; HPMC—semi-synthetic; PLGA—synthetic

Q3. Which polymer is a biodegradable aliphatic copolyester widely used in long-acting injectable depots?

• PLGA (poly(lactic-co-glycolic acid))
• PMMA (polymethyl methacrylate)
• PVP (polyvinylpyrrolidone)
• Polystyrene

Correct Answer: PLGA (poly(lactic-co-glycolic acid))

Q4. Tacticity in polymers refers to which of the following?

• The stereochemical arrangement of pendant groups along the polymer chain
• The degree of chain branching
• The breadth of the molecular weight distribution
• The density of covalent crosslinks

Correct Answer: The stereochemical arrangement of pendant groups along the polymer chain

Q5. Which statement about molecular weight averages is correct?

• Weight-average molecular weight (Mw) is more influenced by high-molecular-weight species than number-average molecular weight (Mn).
• Number-average molecular weight (Mn) is always larger than Mw for polydisperse polymers.
• Mn and Mw are identical for all polymers regardless of distribution.
• Mw is insensitive to the presence of very large polymer chains.

Correct Answer: Weight-average molecular weight (Mw) is more influenced by high-molecular-weight species than number-average molecular weight (Mn).

Q6. The polydispersity index (PDI) for a polymer sample is defined as:

• Mw/Mn
• Mn/Mw
• 1/Mn
• Mw × Mn

Correct Answer: Mw/Mn

Q7. What occurs at the glass transition temperature (Tg) of an amorphous polymer?

• A transition from a glassy to a rubbery state due to increased segmental mobility
• Complete crystalline melting with latent heat absorption
• Scission of covalent backbone bonds
• Increase in number-average molecular weight

Correct Answer: A transition from a glassy to a rubbery state due to increased segmental mobility

Q8. Which factor generally increases polymer crystallinity?

• Greater chain regularity such as isotactic configuration and a linear backbone
• High density of covalent crosslinks
• Bulky, randomly arranged side groups that hinder packing
• Extensive long-chain branching

Correct Answer: Greater chain regularity such as isotactic configuration and a linear backbone

Q9. Which statement best differentiates biodegradation from bioerosion in biomedical polymers?

• Biodegradation implies bond cleavage mediated by biological activity, whereas bioerosion refers to mass loss via dissolution or hydrolysis that may be purely chemical.
• Bioerosion always requires enzymes, while biodegradation is purely hydrolytic.
• Both terms are identical and interchangeable.
• Biodegradation produces no change in molecular weight, while bioerosion does.

Correct Answer: Biodegradation implies bond cleavage mediated by biological activity, whereas bioerosion refers to mass loss via dissolution or hydrolysis that may be purely chemical.

Q10. Which class of polymers typically exhibits predominant surface erosion in aqueous media?

• Polyanhydrides
• PLGA
• PCL (polycaprolactone)
• PMMA

Correct Answer: Polyanhydrides

Q11. Ionic gelation of alginate with calcium ions (Ca2+) is an example of which type of hydrogel crosslinking?

• Physical crosslinking (ionic gelation)
• Covalent crosslinking via free-radical polymerization
• Hydrogen-bonded interpolymer complexation
• Graft copolymerization onto a backbone

Correct Answer: Physical crosslinking (ionic gelation)

Q12. Which statement correctly compares thermoplastics and thermosets?

• Thermoplastics soften upon heating and can be remolded; thermosets are permanently crosslinked and do not melt.
• Thermoplastics are permanently crosslinked; thermosets can be remelted repeatedly.
• Both thermoplastics and thermosets can be solvent-welded and remelted.
• Thermosets have no crosslinks, whereas thermoplastics are highly crosslinked.

Correct Answer: Thermoplastics soften upon heating and can be remolded; thermosets are permanently crosslinked and do not melt.

Q13. Poloxamers (Pluronics) used in drug delivery are best described as:

• ABA triblock copolymers with a hydrophilic–hydrophobic–hydrophilic sequence (PEO–PPO–PEO)
• Random copolymers of lactic and glycolic acid
• Cationic homopolymers used for gene transfection
• Thermoset epoxy networks

Correct Answer: ABA triblock copolymers with a hydrophilic–hydrophobic–hydrophilic sequence (PEO–PPO–PEO)

Q14. Mucoadhesive interactions of polymers with mucus primarily involve:

• Hydrogen bonding and electrostatic interactions with mucin glycoproteins enabling chain interpenetration
• Purely hydrophobic interactions between polymer and mucus
• Only covalent disulfide bonding independent of functional groups
• Crystallization of the polymer at the mucosal surface

Correct Answer: Hydrogen bonding and electrostatic interactions with mucin glycoproteins enabling chain interpenetration

Q15. The number-average degree of polymerization (DPn) is related to the number-average molecular weight (Mn) and monomer molar mass (M0) by:

• DPn = Mn / M0
• DPn = Mn × M0
• DPn = Mw / Mn
• DPn = M0 / Mn

Correct Answer: DPn = Mn / M0

Q16. Which compound is an azo free-radical initiator commonly used in polymerization?

• AIBN (azobisisobutyronitrile)
• Benzoyl peroxide
• Stannous octoate
• Calcium chloride

Correct Answer: AIBN (azobisisobutyronitrile)

Q17. Which polymer exhibits a lower critical solution temperature (LCST) near 32°C, making it thermoresponsive for in situ gelling?

• Poly(N-isopropylacrylamide) (PNIPAM)
• PCL (polycaprolactone)
• PMMA (polymethyl methacrylate)
• Polyanhydride

Correct Answer: Poly(N-isopropylacrylamide) (PNIPAM)

Q18. The primary benefit of PEGylating a nanoparticle surface is to:

• Provide steric stabilization and reduce opsonization, prolonging blood circulation
• Increase polymer crystallinity to slow degradation
• Raise the glass transition temperature of the core polymer
• Impart a strong positive surface charge

Correct Answer: Provide steric stabilization and reduce opsonization, prolonging blood circulation

Q19. Which polymer is a cationic polyelectrolyte frequently investigated for gene delivery?

• Polyethyleneimine (PEI)
• Poly(acrylic acid) (PAA)
• Poly(2-hydroxyethyl methacrylate) (PHEMA)
• Poly(ethylene glycol) (PEG)

Correct Answer: Polyethyleneimine (PEI)

Q20. For pressure-sensitive adhesive applications in transdermal systems, a polymer with Tg well below room temperature provides:

• A rubbery state with tack and conformability
• High brittleness and crack resistance
• Immediate crystallization on the skin
• Guaranteed sterilization stability at high temperatures

Correct Answer: A rubbery state with tack and conformability

Download