Practical procedure for a theoretical investigation of thermodynamics and kinetics aspects of different-scale radical reactions from addition and cyclization to cyclocopolymerization involving maleic anhydride and divinyl ether

• Published in: Polymer (Guilford) 2018-06, Vol.146, p.429-445
• Main Authors: Bolshchikov, Boris D., Tsvetkov, Vladimir B., Serbin, Alexander V.
• Format: Article
• Language: English
• Subjects: Anhydrides; b3lyp; Biomedical materials; Carbon radical; Chain growth; Chain propagation; Chemical reactions; Complex systems; Computer applications; Computer simulation; Copolymer; Cyclization; DFT; DIVEMA; Divinyl ether; Divinyl ethers; Free radicals; Free-radical polymerization; Kinetic control; Kinetics; M06-2X; Macromolecules; Maleic anhydride; Mathematical analysis; MP2; ONIOM; Organic chemistry; Polymerization; Pyran copolymer; Quantum chemistry; Radical reactions; Reaction kinetics; Scaling; Thermodynamics
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2018.05.032

Quantum chemical techniques reasonable in practical simulation of carbon-centered radical reactions were evaluated scaling up from addition and cyclization of small radicals to growing chains in homo-, cross- and cyclo-polymerization. The methods preselected via “cost – deviation from experiment” criteria were explored relative to growing molecular systems of radical cyclocopolymerization between divinyl ether and maleic anhydride: alternating cross-propagation with cyclization and side homopolymerization reactions. The following methods were found to be optimal for estimation of activation barriers and thermodynamics parameters: DFT M06-2X with 6-311+G(d) and 6-311+G (2df,p) basis sets or ONIOM M06-2X/6-311+G(d):B3LYP/6-31G(d) – for more complex systems. Spin-restricted open shell calculations by ROMP2/6-311+G (3df, 2p) have shown unfeasible increase in computational costs retaining similar accuracy. The optimal techniques facilitated new mechanistic insights into regulating the polymerization including kinetic-thermodynamic control factors for regulation of furan-/pyran-related isomerism within the chain that is essential for tailoring functionality of the derivatives. The approach builds methodology basis for research of similar macromolecular systems including alike polymeric platforms for preparations of broad biomedical applications. [Display omitted] •Computational techniques for accurate description of carbon-centered radical reactions of small and polymer molecular scale were evaluated.•The efficient techniques for modeling DVE – MAN copolymerization were found.•DFT M06-2X/6-311+G(d), M06-2X/6-31+G(2df,p), ONIOM M06-2X/6-311+G(d):B3LYP/6-31G(d), B3LYP/6-31G(d) were found optimal.•Novel mechanistic insights into polymerization regulation factors were found.•Kinetic and thermodynamic control factors in the cyclization can be crucial drivers of furan-/pyran- DVEMAN isomerism.