London dispersion forces: This force occurs between all molecules.
London’s dispersion forces can be defined as a temporary attractive force due to the formation of temporary dipoles in a non-polar molecule.
These very weak attractions occur because of the random motions of electrons on atoms within molecules.
London dispersion forces are due to the interaction between non-polar electron cloud bonds, typically the C-C and C-H bonds in the hydrocarbon portions of polymer molecules.
The following figure shows that London dispersion forces are attractive forces between instantaneous dipoles.
