Animation, including orbitals of the polimerization of 1,3-Butadiene. Orbitals were calculated from orca 188.8.131.52.
1: Unpaired electron on polymer and delocalized/fully paired electrons on the monomer
2: Collapse of paired electrons on monomer into unpaired electrons
3: Re-hybridization of the 1 and 4 carbons to SP3
4: Collapse of remaining unpair electrons into pi-bond between the 2 and 3 carbons
5: Overlap of unpaired electrons on the terminal carbon of the polymer and monomer, resulting in bond formation
These models were made through a combination of ORCA, UCSF Chimera, and Blender.