Theoretical evaluation of the order of reactivity of transfer agents utilized in RAFT polymerization: part 2: group R.
Density functional theory, DFT, PBE1PBE functional and 6-31+G(d,p) basis set in Gaussian 03 software were used in order to determine the reactivity order of the R group in RAFT agents used in the radical addition-fragmentation transfer polymerization, through the evaluation of reactivity parameters such as: global and local electronegativity, hardness, softness, and philicity. It was found that the reactivity order is governed by both the number and the composition of the substituent group (primary, secondary or tertiary); that is, the larger those parameters are the larger factors like steric hindrance, polar effects and electronic interchanges are, which favors the breaking of the C-S bond from the adduct radical, permitting the exit of the leaving radical and allowing, as a consequence, the fragmentation step in RAFT polymerization. Trisubstituted dithioesters with structure S = C(Z)S-R, where Z = Phenyl and R = C(CH(3))(2)CONH(2), C(CH3)2Ph or (CH(3))(2)C(6)H(8)OCH(3), in accordance with the previously exposed, presented the most favorable reactivity parameters.
Rodríguez-Sanchez
Isis
I
Centro de Investigación en Materiales Avanzados, S.C. NANOCOSMOS, Miguel Cervantes 120, Complejo Industrial Chihuahua, CP 31109, Chihuahua, Chih, México.
Zaragoza-Contreras
Erasto Armando
EA
Glossman-Mitnik
Daniel
D
D007700:Kinetics; D008962:Models, Theoretical; D015394:Molecular Structure; D058105:Polymerization; D013859:Thiocarbamates / Q000737:chemistry; D013871:Thiones / Q000737:chemistry
D013859:Thiocarbamates; D013871:Thiones; C013321:trithiocarbonic acid