The effect of electron donating and electron withdrawing substituents on the degradation rate of bioabsorbable polymers: a semiempirical computational study

Abstract

The two step hydrolyses of halogen and amine substituted polyglycolic acids are modeled by the semiempirical MNDO hamiltonian using small molecule analogues to determine the effect of the electron donating and withdrawing substituents on the reaction and activation enthalpies. It was seen that halogen substitution on the alkyl portion of the ester increases the rate of hydrolysis by the largest amount, while amino substituents showed much smaller effects. Substitution on the acyl fragment can either accelerate or retard hydrolysis, depending on the relative contributions of the inductive and steric effects.