D'hooge, Dagmar

Desmet, Gilles

Marin, Guy

Reyniers, Marie-Françoise

Sabbe, Maarten

English

Ghent University Academic Bibliography

Laboratory for Chemical Technology, Ghent Universityhttp://www.lct.UGent.beQuantitative first principles based kinetic modeling for the synthesis of well-defined macromolecular architecturesGilles B. Desmet, Dagmar R. D’hooge, Maarten K. Sabbe, Marie-Françoise Reyniers and Guy B. MarinContents: 2 case studies related to Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization1. RAFT polymerization of styrene (     ) using a trithiocarbonate (         ) Calculation of addition-fragmentation rate coefficients Application in a microkinetic model236th Australasian Symposium, Mantra Lorne, 22/11/2016T2. The aminolysis of RAFT-macromolecules  Determination of the reaction mechanism calculation of rate coefficients for a variety of RAFT-agentsTTTTTTaminolysisRAFT polymerizationSHthiol-enefunctionalizedpolymersTHow do RAFT agents help us to obtain control over the chain length in radical polymerization36th Australasian Symposium, Mantra Lorne, 22/11/2016ktDEADM+kdkpIkiM+I IACTIVEFRP3MI IR0T2-cyano-2-propyl-dodecyl trithio-carbonate (CPDT) styreneazobisisobutyronitrile (AIBN)used in this workinitiatormonomerR0kri R0DORMANTkaddkfrag kaddkfragRAFT exchangeR0TTTTTRAFT agentR0TTAb initio calculation of addition-fragmentation reactionsusing a dimer model: 4 model reactions436th Australasian Symposium, Mantra Lorne, 22/11/2016Ab initio calculation• scan conformers: B3LYP/6-31G(d)• geometry optimization andfrequencies: B3LYP/6-31G(d)• ‘single point’ electronic energy:  M06-2X/6-311+G(d,p)R/SR/SR/S R/SR/SR/S R/S R/S R/S R/SModel assumptions• dimer radical to model macroradicala• ethyl group to model dodecyl groupSolvation via COSMO-RSa Lin and Coote, Aust. J. Chem. 2011, 94, 747 1)2)3)4)Gibbs free energy diagrams of the addition-fragmentation reactions536th Australasian Symposium, Mantra Lorne, 22/11/2016𝐾 = 𝑒−∆𝑟𝐺°𝑅𝑇 𝑘+=𝑘𝐵𝑇ℎ𝑒−∆‡𝐺°𝑅𝑇 𝑘− = 𝑘+/𝐾• Rate coefficients are obtained via classical transition state theory:𝑘𝑎𝑑𝑑 =1𝑛0෍𝑖𝑘𝑎𝑑𝑑,𝑖 𝑘𝑓𝑟𝑎𝑔 =σ𝑖 𝑘𝑓𝑟𝑎𝑔,𝑖𝐾𝑖σ𝑖𝐾𝑖• Stereoisomers are taken into account according to the following formulas:Deterministic kinetic model based on methods of momentsa636th Australasian Symposium, Mantra Lorne, 22/11/2016Reaction Equation Ea AkJ mol-1 L mol-1 s-1Dissociation* I2 → 2R0 129.0 1.6 E +15d(Re)Initiation R0 + M → R1 26.0 4.9 E +07ePropagation Ri + M → Ri+1 32.5 4.2 E +07fCombination** Ri + Rj → Ri+j 0.0 5.0 E +08gAddition R0 + TR0 → R0TR0 13.9 7.4 E +06Addition R0 + TRi → R0TRi 24.2 1.6 E +07Addition Ri + TR0 → RiTR0 3.0 9.4 E +06Addition Ri + TRi → RiTRi 15.4 1.7 E +07Fragmentation R0TR0 → R0 + TR0 44.6 9.4 E +12Fragmentation R0TRi → R0 + TRi 48.3 1.2 E +13Fragmentation RiTR0 → Ri + TR0 51.7 2.6 E +12Fragmentation RiTRi → Ri + TRi 53.2 1.2 E +13FRPRAFT** Diffusional limitationsVia composite kt modelc•for 𝑖 < 𝑖gel and 𝑖 < 𝑖SL:𝑘t,iiapp= 𝑘t,11𝑖−𝛼s•for 𝑖 < 𝑖gel and 𝑖 ≥ 𝑖SL:𝑘t,iiapp= 𝑘t,11𝑖SL𝛼l−𝛼s𝑖−𝛼l•for 𝑖 ≥ 𝑖gel and 𝑖 < 𝑖SL:𝑘t,iiapp= 𝑘t,11𝑖gel𝛼gel−𝛼s𝑖−𝛼gel•for 𝑖 ≥ 𝑖gel and 𝑖 ≥ 𝑖SL:𝑘t,iiapp= 𝑘t,11𝑖SL𝛼l−𝛼s𝑖gel𝛼gel−𝛼l𝑖−𝛼gel* Initiator efficiencyb𝑓𝑎𝑝𝑝 =𝐷𝐼𝐷𝐼 + 𝐷𝑡𝑒𝑟𝑚a De Rybel et al., Macromol. Theor. Simul. 2016, in press; b Buback et al., Macromol. Chem. Phys. 1994,195, 2117; c Johnston-Hall  and Monteiro, J. Polym. Sci. Polym. Chem. 2008, 46, 3155-3173; d Van Hookel al, J. Am. Chem. Soc. 1958, 80, 779–782; e Hėberger el al., Int. J. Chem. Kinet. 1993, 25, 249–263; f M. Buback, Macromol. Chem. Phys. 1995, 196, 3267–3280; g Johnston-Hall et al., Macromolecules, 2008, 41, 727–736 Simulation and experimental validation736th Australasian Symposium, Mantra Lorne, 22/11/2016T = 80 °C, TCL = 200, CTA:AIBN = 5:1T = 70 °C, TCL = 400, CTA:AIBN = 5:11. RAFT polymerization of styrene using a trithiocarbonate Calculation of addition-fragmentation rate coefficients Application in a microkinetic model836th Australasian Symposium, Mantra Lorne, 22/11/20162. The aminolysis of RAFT-macromolecules  Determination of the reaction mechanism calculation of rate coefficients for a variety of RAFT-agentsTaminolysisSHthiol-enefunctionalizedpolymersAminolysis of RAFT agents in aprotic solvents: reaction mechanism936th Australasian Symposium, Mantra Lorne, 22/11/2016Gibbs Free Energy Diagram for EthylAmine (EA) + Methyl EthaneDiThioate (MEDT)1036th Australasian Symposium, Mantra Lorne, 22/11/2016(Gibbs free energies in kJ mol-1 at 298.15 K)R = C2H5Z,Pn =CH3Amine assisted transition state are asynchronous and early1136th Australasian Symposium, Mantra Lorne, 22/11/2016-80-60-40-200204000.511.522.533.54Energy (kJ/mol)Distance (Å)Reaction CoordinateEvolution of distances along thereaction coordinateC-S1 S1-H1 H1-N N-H2 H2-S EH1-transfer H2-transferR = C2H5Z,Pn =CH3Aminolysis of RAFT agents in aprotic solvents: reaction mechanism1236th Australasian Symposium, Mantra Lorne, 22/11/20165891011• Proton transfer in transition states can be assisted by amines and by thiolsGibbs Free Energy Diagram for EthylAmine (EA) + Methyl EthaneDiThioate (MEDT)1336th Australasian Symposium, Mantra Lorne, 22/11/2016(k+ and k- in L mol-1 s-1 or s-1)R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11k+ 1.3E+04 2.3E-04 2.4E+00 4.3E-06 2.2E+02 6.2E+12 5.6E+12 3.4E+05 1.1E-06 7.8E+06 4.0E-03k- 1.3E+10 7.5E-21 1.5E-05 2.2E-17 7.2E-15 7.0E+12 7.6E+07 1.8E-06 3.6E-23 5.0E+01 2.1E-14(Gibbs free energies in kJ mol-1 at 298.15 K)diffusional limitations become important!R = C2H5Z,Pn =CH3The coupled encounter pair model to account for diffusion for TS 6 and 7,,111diffapp kkk,,11diffapp kKkkPSSA• Diffusion of A+B towards [AB] via the model of Smoluchowski: 𝑘𝑑𝑖𝑓𝑓 = 4𝜋 𝑁𝐴 𝜎 𝐷𝐴𝐵 σ = reaction distance: from ab initio TS geometries DAB = mutual diffusivity coefficienta 𝐷𝐴𝐵 =𝐷A,𝐷B𝐷𝑠𝑜𝑙𝑣𝑒𝑛𝑡36th Australasian Symposium, Mantra Lorne, 22/11/2016TS6a Liu et al. Ind Eng Chem Res 2011, 50, 4776. 14MDDiffusivity coefficients based on molecular dynamics1536th Australasian Symposium, Mantra Lorne, 22/11/2016012345670 20 40RMSD (Å)Time (ps)01E-082E-083E-084E-085E-080 20 40Diffusion coefficient (m² s-1)Time (ps)equilibrated𝐷𝑖,𝑇𝐻𝐹 =16lim𝑡→∞𝑑𝑑𝑡𝑟 𝑡 − 𝑟 0 ²• NVT ensemble in 8 nm3 box for 50 picosecondsk+ kdiff kapp,+R6 6.2E+12 2.1E+09 2.1E+09Rate and affinity analysis reveal the dominant path and the nature of the elementary steps for the aminolysis of MEDT1636th Australasian Symposium, Mantra Lorne, 22/11/2016Dominant mechanism𝐴 = 𝑅𝑇 𝑙𝑛𝑟𝑓𝑟𝑟Prediction of conversion profiles for other RAFT-agents1736th Australasian Symposium, Mantra Lorne, 22/11/2016Reaction of 10-3 mol L-1 RAFT-macromolecule with 5 x 10-3 mol L-1 ethylamine in THF at 25 °C for dithioates, thiobenzoates, xanthates, trithiocarbonates and dithiocarbamates:• dithiocarbamates are not reactive at room temperature! (in agreement withexperiment observationsa)• conversion of xanthates anddithiobenzoates show good agreement with literatureb (<factor 2)• reaction of trithiocarbonates slower thanxanthatesba Le Neindre et al, Polym Chem 2013, 4, 5577b Kabachii et al, Pol Sci Ser A 2006, 48, 717Conclusion: first principles techniques are a valuable tool toobtain reaction parameters for kinetic models1836th Australasian Symposium, Mantra Lorne, 22/11/20161. RAFT polymerization of styrene with a trithiocarbonate– Calculation of addition-fragmentation rate coefficients– Implementation in microkinetic model• conversions• chain lengths• dispersities2. Aminolysis of RAFT-macromolecules – Determining the dominant mechanism using ab initio based kinetic model• quasi-equilibrated formation of a zwitterion• amine-assisted diffusion-limited proton transfer over a complex intermediatetowards a neutral intermediate• rate limiting amine-assisted breakdown of the neutral intermediate towards the product– Simulation of conversion of range of RAFT agents• Reactivity: thioates > thiobenzoates > xanthates ≥ trithiocarbonates >> dithiocarbamatesAcknowledgements1936th Australasian Symposium, Mantra Lorne, 22/11/2016• Nils De Rybel • LCT colleaguesThanks to FundingQuestions?2036th Australasian Symposium, Mantra Lorne, 22/11/2016

Quantitative first principles based kinetic modeling for the synthesis of well-defined macromolecular architectures

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Quantitative first principles based kinetic modeling for the synthesis of well-defined macromolecular architectures

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