Question

The polymer Kevlar, a condensation polymer, is used as reinforcement in car tires, strings of archery bows, and as a component of bulletproof vests. A repeat unit is n copies of the following structure: A benzene ring with a C double bonded to O attached to both points. The right CO is also single bonded right to NH, which is single bonded right to the left point of another benzene ring. That ring also has NH attached to its right point.

Part A Draw the structure of the monomer (with greater molar mass) that yields Kevlar.

Part B Draw the structure of the monomer (with least molar mass) that yields Kevlar.

Answer 1

Monomer of Kevlar has 14 C, two N and two O atoms with hydrogens. The cis monomer does not pack well and has stearic hindrance, less H- bonding thus less dense(cis form).

Trans monomer does not has stearic hindranse forms good fibre due to hydrogen bonding thus densily packed so it is called greater molar mass monomer (trans form).

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