In an idealized step-growth polymerization to synthesize the polyester Terylene (Dacron), exactly mo — Polymers Chemistry Question
Question
In an idealized step-growth polymerization to synthesize the polyester Terylene (Dacron), exactly $100$ molecules of ethylene glycol react completely with exactly $100$ molecules of terephthalic acid to form a single, linear, alternating, un-cyclized polymer chain. What is the total number of water molecules eliminated in this process?
💡 Solution & Explanation
The formation of a single alternating linear chain from $n$ molecules of diol and $n$ molecules of diacid involves joining $2n$ total monomer molecules. The number of ester linkages formed to join $2n$ units in a straight line is $2n - 1$. Since one $H_2O$ molecule is eliminated per linkage, for $n=100$, the number of $H_2O$ molecules is $2(100) - 1 = 199$.