Chapter 26, Problem 26.11P

Interpretation Introduction

Interpretation:

Kevlar is a high-strength polymer used in body armor and bicycle tires. It is a condensation polymer synthesized from $\text{benzene-1, 4-diamine}$ ($\text{para-phenylenediamine}$) and $\text{benzene-1, 4-dicarbonyl chloride}$ ($\text{terephthaloyl chloride}$). The repeating unit for Kevlar is to be drawn.

Concept introduction:

Step-growth polymerization occurs when molecules throughout a mixture join with any other molecule that has an appropriate functional group available to react, whether it is a monomer unit or another polymer molecule. The reaction mixture contains two different compounds, each of which has two reactive functional groups. The two monomers are linked together in the first step. The reaction continues and the chain length increases because the product also has two reactive functional groups. Each of those functional groups can therefore produce another group. As the reaction progresses, long chains may

join, greatly increasing the size of the chain in a single step.