Cross-link

In polymer chemistry, a cross-link is a chemical bond or small group of bonds that connects two bigger polymer molecules.^[1] Making cross-links is called cross-linking or curing, and is an important part of making many different materials.

A chemical that creates cross-links in a polymer is called a cross-linking agent. If sulfur is used as the cross-linking agent, the process is sometimes called vulcanization. Oxygen from the air can also be a cross-linking agent; chemicals that are cross-linked by oxygen are called drying oils.

The amount of cross-links in a sample can change properties like strength, density, and flexibility. The amount of cross-links is also linked to the swelling capacity, which is used to measure how cross-linked something is.^[2]

1. ↑ International Union of Pure and Applied Chemistry. "crosslink". Compendium of Chemical Terminology Internet edition.
2. ↑ "Swelling estimates cross-link". Chemical & Engineering News Archive. 44 (47): 24. 1966. doi:10.1021/cen-v044n047.p024a.