Polymerisation mechanisms: identify the WRONG statement among the following about addition (chain-growth) and condensation (step-growth) polymerisations.

Introduction / Context:
Understanding the distinction between chain-growth and step-growth mechanisms is central to predicting molecular weight development, kinetics, and typical product families. This question asks you to spot the statement that contradicts well-established polymerisation pathways for common materials.

Given Data / Assumptions:

• Addition polymers arise when monomer double bonds open and add to growing radicals/ions/coordination sites.
• Condensation polymers form via stepwise reactions often with small-molecule elimination.
• PTFE, polyethylene, and phenol–formaldehyde (Bakelite) are representative materials.

Concept / Approach:
Polyethylene and PTFE (Teflon) are produced by chain-growth addition of unsaturated monomers (ethylene and tetrafluoroethylene). Phenol–formaldehyde (Bakelite) forms via step-growth condensation reactions creating methylene bridges with water elimination. Therefore, any claim that PTFE forms by step growth is incorrect.

Step-by-Step Solution:

Verification / Alternative check:
Catalyst and radical processes for vinyl monomers (including tetrafluoroethylene) are well documented as chain-growth; Bakelite synthesis involves stepwise phenol-formaldehyde condensation.

Why Other Options Are Wrong:

• (a), (b), (d), (e) are correct statements; the only incorrect one is (c).

Common Pitfalls:
Confusing “addition” vs. “addition-condensation” terminologies in older literature; here PTFE is clearly an addition polymer.

Final Answer:
Teflon (PTFE) is formed by step-growth polymerisation.