Theoretical elucidation on mechanism and reactivity of bisphenol A derivatives as inhibitors and radical scavengers in methacrylate polymerization

To elucidate the mechanism and activity difference of bisphenol A derivatives (BSADs), i.e. hydroquinone, 2,2'-biphenol, 4,4'-biphenol, bisphenol A and diethylstilbestrol, as inhibitors and radical scavengers in methyl methacrylate (MMA) polymerization, a combined quantum chemical method, labeled as (RO)B3LYP/6-311 +G(2d,2p)//AMI/AMI, was employed to calculate O-H bond dissociation enthalpies (BDEs) and ionization potentials (IPs) for these compounds. The calculation results reveal that BSADs scavenge radicals generated during NIMA polymerization through a direct H-atom transfer process. Furthermore, the difference in inhibition activity and stoichiometric factors for BSADs was elucidated by the O-H BDEs. In addition, substituent effects on BDE were employed to give a deeper insight into the structure-activity relationships for BSADs. (c) 2004 Elsevier B.V. All rights reserved.