Copolymers and homopolymers: which listed material is not a polymer of two monomers?

Introduction / Context:
Polymers may be homopolymers (one monomer) or copolymers (two or more monomers). Identifying which materials are copolymers helps anticipate properties and applications.

Given Data / Assumptions:

• Teflon is PTFE, produced from a single monomer (tetrafluoroethylene).
• Bakelite forms from phenol and formaldehyde (two monomers; condensation).
• SBR is a copolymer of styrene and butadiene.

Concept / Approach:
A homopolymer is built from repeating units of a single monomer; PTFE fits this definition. Both Bakelite and SBR involve two different monomers, classifying them as copolymers (though Bakelite forms a crosslinked network via condensation rather than addition).

Step-by-Step Solution:
Identify PTFE as homopolymer of tetrafluoroethylene → not a two-monomer polymer.Recognise Bakelite (phenol + formaldehyde) and SBR (styrene + butadiene) as two-monomer systems.

Verification / Alternative check:
Polymer reference charts list PTFE as a homopolymer with exceptional chemical resistance and low surface energy.

Why Other Options Are Wrong:
Bakelite and SBR both use two monomers; “None of these” therefore cannot be correct.

Common Pitfalls:
Assuming “network polymers” like Bakelite are not considered in the monomer count; despite crosslinking, two distinct monomers are used.

Final Answer:
Teflon