oligomers

Oligomers are short chains of monomer units larger than a single molecule but shorter than polymers. They have a limited degree of polymerization (DP), typically 2 to 20 repeating units, though definitions vary. Oligomers can be linear, branched, or cyclic and may carry functional end groups that enable further reactions. Their finite size gives properties distinct from long polymers, such as lower viscosity and different solubility.

Oligomers form by controlled or incomplete polymerization, or by dedicated oligomerization reactions. Synthesis often aims for defined end groups and narrow molecular weight distributions. Oligomers serve as intermediates in polymer production and materials science, or as end products in their own right.

In biology, oligomers include oligopeptides, oligosaccharides, and oligodeoxynucleotides or oligoribonucleotides—short chains of amino acids, sugars, or nucleotides. They can exhibit distinct folds, activities, or recognition properties compared with longer polymers.

Common examples include oligoesters, oligoethers, and cyclic oligomers such as cyclodextrins. Oligomers are used as synthesis intermediates, additives or crosslinkers, and sometimes as drug carriers or analytical standards.

Size is described by DP or molecular weight; measurement uses mass spectrometry, gel permeation chromatography, and MALDI-TOF. The term implies a small, finite number of repeating units rather than an indefinite polymer chain.