Pendant group
Encyclopedia
A pendant group or side group is a group of molecules attached to a backbone chain
Backbone chain
In polymer science, the backbone chain or main chain of a polymer is the series of covalently bonded atoms that together create the continuous chain of the molecule....

 of a long molecule. Usually, this molecule would be a polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

. Pendant groups are different from pendant chains
Side chain
In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called "main chain" or backbone. The placeholder R is often used as a generic placeholder for alkyl group side chains in chemical structure diagrams. To indicate other non-carbon...

, they are neither oligomeric nor polymeric.



For example, the phenyl group
Phenyl group
In organic chemistry, the phenyl group or phenyl ring is a cyclic group of atoms with the formula C6H5. Phenyl groups are closely related to benzene. Phenyl groups have six carbon atoms bonded together in a hexagonal planar ring, five of which are bonded to individual hydrogen atoms, with the...

s are the pendant groups on a polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...

 chain.

Large, bulky pendant groups such as adamantyl usually raise the glass transition temperature (Tg) of a polymer by preventing the chains from sliding past each other easily. Short alkyl pendant groups may lower the Tg by a lubricant effect.
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