Step-growth polymerisation produces which of the following well-known polymers by a condensation route?

Introduction / Context:
Polymer synthesis routes strongly influence structure and properties. Step-growth (condensation) polymerisation typically reacts difunctional monomers to form high molecular weight only at high conversion, often producing small-molecule byproducts such as water or methanol. Identifying which commercial polymer arises from step-growth is a frequent exam task.

Given Data / Assumptions:

• Terylene (PET) results from the reaction of terephthalic acid (or its dimethyl ester) with ethylene glycol.
• Polybutadiene, PVC, PP, and PS are formed predominantly via chain-growth free-radical, coordination, or anionic mechanisms.

Concept / Approach:
In step-growth, difunctional monomers (e.g., diacids and diols) polymerise to form linear chains. PET is the archetypal saturated polyester produced by this method and widely used for fibres (dacron/terylene), films, and bottles. The other listed polymers are addition polymers assembled by successive propagation of unsaturated monomer units, not by condensation of bifunctional monomers.

Step-by-Step Solution:
Compare each option’s known synthesis route.Identify PET as the step-growth polyester.Select “Terylene (PET).”

Verification / Alternative check:
Standard polymer chemistry texts map PET to step-growth; commodity polyolefins and vinyls derive from chain-growth mechanisms.

Why Other Options Are Wrong:
Polybutadiene: chain-growth (diene polymerisation).PVC / PP / PS: classic chain-growth vinyl/olefin systems.

Common Pitfalls:
Confusing “polyester” as a broad class; only saturated polyesters like PET for fibres are step-growth, whereas “unsaturated polyesters” are thermoset resins used in composites.

Final Answer:
Terylene (PET, a saturated polyester)