B
Nylon-66 – $[-NH-(CH_2)_6-NH-CO-(CH_2)_4-CO-O-]_n$
C
Terylene – $[-OCH_2-CH_2-CO-C_6H_4-CO-]_n$
D
PMMA – $[-CH_2-C(CH_3)(COOCH_3)-]_n$
The answer is C.
Solution
Neoprene is polychloroprene, $[-CH_2-C(Cl)=CH-CH_2-]_n$; correctly matched. PMMA (polymethyl methacrylate) is $[-CH_2-C(CH_3)(COOCH_3)-]_n$; correctly matched. Terylene (Dacron) is a polyester of ethylene glycol and terephthalic acid. Its repeat unit is $[-O-CH_2-CH_2-O-CO-C_6H_4-CO-]_n$, with an ester oxygen between each $CH_2$ and C=O. The structure given for terylene, $-OCH_2-CH_2-CO-C_6H_4-CO-$, has no oxygen between $CH_2$ and C=O, so it is not the correct ester structure. (The Nylon-66 unit is written with an extra O, but the key treats it as matched; nylon-66 is $[-NH-(CH_2)_6-NH-CO-(CH_2)_4-CO-]_n$.) So, as per the answer key, terylene is not correctly matched.
ConceptRepeat unit of Terylene
Polymers in past papers
34 questions from this chapter have appeared across 23 exam years.