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Reference.org
Ring-opening polymerization
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<p>In <a href="/facts/Polymer_chemistry/wdfr6fs4">polymer chemistry</a>, ring-opening polymerization (ROP) is a form of <a href="/facts/Chain-growth_polymerization/ltonCdDy">chain-growth polymerization</a> in which the <a href="/facts/End_group/scTJ3Xga">terminus</a> of a <a href="/facts/Polymer/eF32E50K">polymer</a> chain attacks <a href="/facts/Cyclic_compound/TH2ReKIQ">cyclic monomers</a> to form a longer polymer (see figure). The reactive center can be <a href="/facts/Radical_(chemistry)/qFymuVoT">radical</a>, <a href="/facts/Anion/wrbwhF3z">anionic</a> or <a href="/facts/Cation/wrbwhF3z">cationic</a>. </p><p>Ring-opening of cyclic monomers is often driven by the relief of <a href="/facts/Ring_strain/seIIaK2k">bond-angle strain</a>. Thus, as is the case for other types of polymerization, the <a href="/facts/Enthalpy/bBou8lCE">enthalpy</a> change in ring-opening is negative. Many rings undergo ROP. </p>