Synthesis, spectral characterization and DFT calculations of novel macro MADIX agent: mechanism of addition-fragmentation reaction of xanthate compound

In this study, the macromolecular design was performed via interchange of xanthates (MADIX) polymerization. The macro RAFT/MADIX agent containing the structure of polytetrahydrofuran (PTHF) (average Mn ~ 1000 g/mol) was synthesized to use in the polymerization. PS-b-PTHF-b-PS triblock copolymer was obtained by styrene-controlled radical polymerization using the RAFT/MADIX agent. The plot of ln [M] o /[M] versus monomer concentration versus polymerization time exhibits first-order kinetic behavior. Block copolymer formation has a controlled character. The formation of the narrow molecular weight polymer controlled by the styrene’s RAFT/MADIX polymerization is confirmed by the increase in the polymerization time of the molecular weight. The results are in good agreement with theoretical values. Block copolymers having a narrow molecular weight distribution and a predetermined average molecular weight have been obtained using this polymerization process. The synthesized RAFT/MADIX agents, polymer, and copolymers were characterized by NMR and FT-IR spectroscopy, GPC, and differential scanning calorimetry. Based on the vibration analysis, the thermodynamic properties of the compound were also calculated. Optimized structure, frontier molecular orbitals (HOMO and LUMO) and global reactivity descriptors were analyzed by DFT calculations. As a result of the DFT study with trimer and hexamer; although the chain length is increased, the energy parameters obtained are very proximate to each other.