In polymer chemistry, a
chain extender is a low molecular weight (MW) reagent that converts polymeric precursors to higher molecular weight derivatives. Often, it is convenient to prepare a polymer at an intermediate MW, which are suitable for solution- or melt-processing. At or near the final stages of production, the material is treated with a chain extender. Typically, chain extenders are
bifunctional, i.e., they have two functional groups, which can link together two polymers. Representative classes of chain extenders are
,
,
, or
. Chain extenders are often applied to polyurethanes.
