Each also has a hydrogen atom bonded to it. Phenyl groups are benzene rings where one of the carbon atoms is bonded to another molecule, making the entire cyclic structure a substituent or side group of that molecule. Phenyl groups are relatively large and bulky, and generally have a significant influence on the properties of the polymer they are present in. Primary bonds are between atoms of the same molecule and are strongest. They result from the sharing of two electrons by both atoms.
Secondary bonds are between atoms of different molecules or remote sections of the same molecule.
They are the result of attractions due to polarity, induced polarity due to displaced electrons, and temporary polarity due to vibration and spinning. These bond forces are weak in comparison to primary bonds. The end product generally has properties intermittent between those of polymers of the two composing monomers. The two materials must have compatibility to be copolymerized. Covalent are the strongest of the molecular bonds.