Polymer classification: which of the following materials is a homopolymer (formed from a single monomer species, without copolymerization)?

Introduction / Context:
A homopolymer is produced by polymerizing only one type of monomer, while a copolymer results from two or more different monomers. Distinguishing these classes is foundational in polymer science because it predicts repeat-unit chemistry, crystallinity, processing window, and end-use properties.

Given Data / Assumptions:

• The options include common industrial polymers and resins.
• We interpret “homopolymer” as the repeat unit originating from a single monomer type.
• Trade names correspond to well-known chemistries (e.g., Bakelite = phenol–formaldehyde).

Concept / Approach:
Neoprene is polychloroprene, obtained by addition polymerization of a single monomer, chloroprene (2-chloro-1,3-butadiene). Hence, it is a homopolymer. In contrast, Bakelite is a condensation polymer formed from phenol and formaldehyde (copolymer network). Nylon-66 is a condensation copolymer produced from hexamethylene diamine and adipic acid. Terylene (polyethylene terephthalate, PET) is a condensation copolymer of ethylene glycol and terephthalic acid.

Step-by-Step Solution:
Identify each polymer's monomer(s).Neoprene: single monomer → chloroprene → homopolymer.Bakelite: phenol + formaldehyde → copolymer network.Nylon-66: diamine + diacid → copolymer.Terylene (PET): glycol + acid → copolymer.

Verification / Alternative check:
Manufacturer data and standard textbooks list neoprene as polychloroprene with one monomer species in the chain backbone.

Why Other Options Are Wrong:
Bakelite: two monomers; crosslinked network.Nylon-66: two monomers (salt formation), not a homopolymer.Terylene/PET: two monomers, not a homopolymer.

Common Pitfalls:
Assuming trade names imply homopolymer; many common materials are actually copolymers or condensation networks.

Final Answer:
Neoprene