cross-linking

thumb|Vulcanization is an example of cross-linking. Schematic presentation of two "polymer chains" (blue and green) cross-linked after the vulcanization of natural rubber with [[sulfur (n = 0, 1, 2, 3, ...).]]

thumb|right|493x493px|link=https://goldbook.iupac.org/terms/view/C01409|IUPAC definition for a crosslink in polymer chemistry In chemistry and biology, a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural polymers (such as proteins).