Reaction involving sites or groups on existing macromolecules or an
interaction between existing macromolecules that results in the formation
of a small region in a macromolecule from which at least four chains emanate.
Notes:
- The small region may be an atom, a group of atoms, or a number
of branch points connected by bonds, groups of atoms, or oligomeric chains.
- A reaction of a reactive chain end of a linear
macromolecule with an internal reactive site of another linear macromolecule
results in the formation of a branch point, but is not regarded as a crosslinking
reaction.
Source:
PAC, 2007, 79, 1801
(Definitions of terms relating to the structure and processing of sols, gels, networks,
and inorganic-organic hybrid materials (IUPAC Recommendations 2007))
on page 1821