Based on computational thinking and tooling and concrete problem-solving method

the Gaussian software was used in the teaching of polymer chemistry to present directly

accurately and animatedly the process of back biting in free radical polymerization of ethylene

the propagation in free radical polymerization of vinyl chloride and of ethylene

and the structure of the chain radical in free radical polymerization of ethylene. And this make them visible and vivid

and can be understood easier and more accurately by the students. With UHF/6-31G(d)

it is found that all the H atoms in the chain radical in free radical polymerization of ethylene have partial positive charge

while all the C atoms have partial negative charge

and the activation energy of the process of back biting via six-membered ring transition state forming C4 branch is 115.6kJ/mol. It is also found that during the transfer of H atom in the above back biting process

the positive charge of the transferring H atom is decreased

the negative charge of the C atom that the H atom is transferring to is increased

and the negative charge of the C atom that the H atom is transferring from is decreased

and the energy of the 2° radical formed being 9.3kJ/mol less. The calculations also show that back biting via seven-membered ring and fivemembered ring transition state forming C5 and C3 branch

respectively

having activation energy of 99.7kJ/mol and 150.6kJ/mol.