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Reference.org
Repeat unit
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<p>A repeat unit or repeating unit , or mer, is a part of a <a href="/facts/Polymer/eF32E50K">polymer</a> whose repetition would produce the complete polymer chain (except for the <a href="/facts/End_group/scTJ3Xga">end groups</a>) by linking the repeat units together successively along the chain, like the beads of a necklace. </p> <p>A repeat unit is sometimes called a mer (or mer unit) in <a href="/facts/Polymer_chemistry/wdfr6fs4">polymer chemistry</a>. "Mer" originates from the <a href="/facts/Greek_Language/pzDd6eIz">Greek</a> word <i>meros</i>, which means "a part". The word polymer derives its meaning from this, which means "many mers". The mer is not the same thing as a <a href="/facts/Monomer/Gw3CltMb">monomer</a>—a mer is a repeating unit within a larger molecule, whereas a monomer is an actual molecule that exists independently, either prior to <a href="/facts/Polymerization/1hmBz7Ur">polymerization</a> or after decomposition. </p>