Michiel Coghe polymerization Ab initio based kinetic modeling of homogeneous RAFT

196 Pages·2016·5.85 MB·English

Ab initio based kinetic modeling of homogeneous RAFT
polymerization
Michiel Coghe
Supervisors: Prof. dr. Marie-Françoise Reyniers, Prof. dr. ir. Dagmar D'hooge
Counsellor: Ir. Gilles Desmet
Master's dissertation submitted in order to obtain the academic degree of
Master of Science in Chemical Engineering
Department of Chemical Engineering and Technical Chemistry
Chair: Prof. dr. ir. Guy Marin
Faculty of Engineering and Architecture
Academic year 2015-2016
FACULTY OF ENGINEERING AND ARCHITECTURE

Department of Chemical Engineering and Technical Chemistry
Laboratory for Chemical Technology
Director: Prof. Dr. Ir. Guy B. Marin

Laboratory for Chemical Technology

Declaration concerning the accessibility of the master thesis

Undersigned,

Michiel Coghe

Graduated from Ghent University, academic year 2015-2016 and is author of the
master thesis with title:

Ab initio based kinetic modelling of RAFT polymerization

The author(s) gives (give) permission to make this master dissertation available for
consultation and to copy parts of this master dissertation for personal use.
In the case of any other use, the copyright terms have to be respected, in particular with
regard to the obligation to state expressly the source when quoting results from this master
dissertation.

1st June 2016

Michiel Coghe

Laboratory for Chemical Technology • Technologiepark 914, B-9052 Gent • www.lct.ugent.be
Secretariat : T [phone] • F [phone] • [email protected]
Acknowledgements

Deze thesis is niet louter tot stand gekomen door de inspanningen van één persoon, maar
is te danken aan de inbreng van verschillende personen die mij bijstonden tijdens mijn
laatste jaar als ingenieursstudent. Eerst en vooral zou ik mijn begeleider, Gilles Desmet,
uitdrukkelijk willen bedanken. Hij was steeds bereid om me bij te staan met goede raad
en zonder hem had ik mijn thesis niet kunnen afwerken met dezelfde trots en voldoening
die nu kan getuigen. Niet alleen op academisch vlak heeft hij mij geholpen, maar ook
tijdens mijn zoektocht naar het pad voor de toekomst was hij een zeer welkome
raadgever. Bovendien zou ik ook graag een teken van dank uitten aan prof. dr. Marie-
Françoise Reyniers, prof. dr. ir. Dagmar D’hooge om toe te zien dat mijn onderzoek in de
juiste banen verliep. Alsook breng ik een dankwoord aan prof. dr. ir. Guy Marin en
iedereen die geassocieerd is aan het Laboratorium voor Chemische Technologie (LCT,
voor de vrienden) om dit onderzoek mogelijk te maken en om ons, de studenten, te
voorzien van alle nodige middelen om onze thesis op een aangename en efficiënte manier
tot een goed einde te kunnen brengen.
Nog een persoon aan wie ik veel te danken heb is mijn vriendin, Anneke. Ze wist mij
steeds weer een hart onder de riem te steken wanneer ik de moed wat liet hangen.
Bovendien kon ik bij haar steeds rekenen op een luisterend oor wanneer ik iemand zocht
om mijn ideeën bij te staven. Ook al had ze er meestal geen boodschap aan, het was voor
mij telkens weer een ideale gelegenheid om mijn gedachten terug op orde te brengen.
Tot slot ga ik hier ook nog mijn ouders, familie en vrienden bedanken, aangezien het wel
een beetje flauw zou zijn moest ik dat niet doen. Bovendien zijn zij uiteindelijk de echte
reden waarom ik me elke dag opnieuw goed in mijn vel voel en ik weet dat ze er ook
zullen zijn op de momenten wanneer dat niet zo is.
“Yes we can!”
- Obama, B.
Michiel Coghe
June 2016
Ab initio based kinetic modeling of
homogeneous RAFT polymerization

Author: Michiel Coghe
Supervisors: Prof. dr. Marie-Françoise Reyniers, Prof. dr. ir. Dagmar R. D’hooge
Counsellor: Ir. Gilles Desmet
Master’s dissertation submitted in order to obtain the academic degree of Master of
Science in Chemical Engineering
Department of Chemical Engineering and Technical Chemistry
Chairman: Prof. dr. ir. Guy B. Marin
Faculty of Engineering and Architecture
Academic year 2015-2016
Abstract
A computational investigation is presented on i) the homopolymerization of vinyl acetate (VAc),
ii) the copolymerization of VAc and styrene (St), iii) the controlled block copolymerization of
VAc and St using a so-called switchable RAFT agent and iv) the RAFT polymerization of St.
For the homopropagation of VAc, it is shown that there is a significant effect of head-to-head
additions on the propagation kinetics. Theoretical predictions match well with experimental
observations. Next, the scope is expanded to include all homo- and crosspropagation reactions for
the copolymerization of VAc with St with a focus on the effect of the penultimate unit on the
propagation kinetics. A comparison between the terminal and penultimate copolymerization
model shows that there is only a slight difference between the model predictions of the
copolymerization propagation rate and the copolymer composition.
Then, the RAFT block copolymerization of VAc with St controlled by N-(4-pyridinyl)-N-methyl
dithiocarbamate (PMDTC) is investigated. First, it is shown that protonation of the RAFT agent
(the so-called ’switching’) significantly stabilizes the intermediate adduct radical, favoring the
addition reaction but hindering the fragmentation reaction. Secondly, the kinetic parameters for all
the possible addition fragmentation reactions are determined during both stages of the two-stage
synthesis of VAc/St block copolymer. First, there is polymerization of St, a more-activated
monomer (MAM), with protonated PMDTC, followed by a polymerization of VAc, a less-
activated monomer (LAM), by deprotonated PMDTC.
Finally, the kinetic parameters for the addition-fragmentation reactions of the 2-cyano-2-propyl
dodecyl trithiocarbonate (CPDT) mediated RAFT polymerization of St are calculated and
implemented into a kinetic model. This ab initio based kinetic model is then used to successfully
predict molecular weight, monomer conversion and polydispersity.
Ab initio based kinetic modeling of homogeneous
RAFT polymerization
Michiel Coghe
Supervisors: Prof. dr. Marie-Françoise Reyniers, Prof. dr. ir. Dagmar R. D’hooge
Counsellor: ir. Gilles Desmet
Abstract A computational investigation is presented on i) the polymerization allows enhanced control over the molecular
homopolymerization of vinyl acetate (VAc), ii) the structure of the polymer product in terms of molar mass
copolymerization of VAc and styrene (St), iii) the controlled distribution, chain-end functionality and molecular
block copolymerization of VAc and St using a so-called architecture, all while maintaining the versatility and
switchable RAFT agent and iv) the RAFT polymerization of St. economic advantages of conventional free radical
For the homopropagation of VAc, it is shown that there is a polymerization [1-5]. This has opened the doors to the
significant effect of head-to-head additions on the propagation
synthesis of novel materials with advanced physicochemical
kinetics. Theoretical predictions match well with experimental
properties, which can be used in a range of technological
observations. Next, the scope is expanded to include all homo-
applications [6-11].
and crosspropagation reactions for the copolymerization of VAc
with St with a focus on the effect of the penultimate unit on the Kinetic modeling of RAFT polymerization processes can
propagation kinetics. A comparison between the terminal and serve as a useful tool during both product and process design.
penultimate copolymerization model shows that there is only a In order for the kinetic model to be reliable, a large set of
slight difference between the model predictions of the kinetic parameters has to be known. Typically, this
copolymerization propagation rate and the copolymer information is obtained based on experimental methods, but
composition. these can have significant limitations and often rely on model-
Then, the RAFT block copolymerization of VAc with St
based assumptions. Computational chemistry offers an
controlled by N-(4-pyridinyl)-N-methyl dithiocarbamate
attractive alternative for obtaining both qualitative and
(PMDTC) is investigated. First, it is shown that protonation of
quantitative information on reaction kinetics and
the RAFT agent (the so-called ’switching’) significantly stabilizes
the intermediate adduct radical, favoring the addition reaction thermodynamics. These methods are commonly known as ab
but hindering the fragmentation reaction. Secondly, the kinetic initio methods, since the calculations are based on quantum
parameters for all the possible addition fragmentation reactions chemistry [12, 13].
are determined during both stages of the two-stage synthesis of
VAc/St block copolymer. First, there is polymerization of St, a
more-activated monomer (MAM), with protonated PMDTC,
followed by a polymerization of VAc, a less-activated monomer
(LAM), by deprotonated PMDTC.
Finally, the kinetic parameters for the addition-fragmentation
reactions of the 2-cyano-2-propyl dodecyl trithiocarbonate
(CPDT) mediated RAFT polymerization of St are calculated and
implemented into a kinetic model. This ab initio based kinetic
model is then used to successfully predict molecular weight,
monomer conversion and polydispersity.

Keywords kinetic modeling, ab initio, vinyl acetate
homopropagation, vinyl acetate styrene copolymerization, Figure 1: General reaction scheme of the RAFT mechanism
Reversible addition-fragmentation chain transfer (RAFT)
polymerization II. METHODOLOGY
All electronic structure calculations in this work have been
I. INTRODUCTION performed using the Gaussian-09 package [14]. A general
D
uring the last century radical polymerization has flowchart of the applied methods and procedures is given in
become one of the most industrially relevant Figure 2. The conformational search and the subsequent
production processes for a wide range of polymeric geometry optimization and frequency calculation in the
materials. In recent years, the development of controlled quasiharmonic oscillator approximation [15] are performed
radical polymerization techniques (CRP) has revolutionized using the B3LYP hybrid functional with the 6-31G* basis set.
polymer chemistry and has received a lot of scientific Electronic energies were obtained using single-point
attention. Reversible addition-fragmentation chain transfer calculations at the M06-2X level of theory with the 6-
polymerization, or simply RAFT polymerization, is amongst 311+G** basis set. Solvent effects are taken into
the most popular CRP techniques. A general reaction scheme consideration by applying the COSMO-RS solvation model
of the RAFT mechanism is shown in Figure 1. RAFT [16].

Michiel Coghe is with the Chemical Engineering Department,
Ghent University (UGent), Gent, Belgium.
E-mail: [email protected] .
Initial guess of
molecular geometry
Conformational search
and
geometry optimization
B3LYP/6-31G*
Frequency Single-point energy Application of
calculation calculation solvation model
B3LYP/6-31G* M062X/6-311+G** COSMO-RS

Ground-state
Partition
electronic Figure 3: Different modes of propagation when accounting for the
functions
energy possibility of inverted monomer addition.
Gas-phase Gibbs free Table 1: Comparison of experimental versus theoretical values of the
Gibbs free energy of bulk propagation kinetics. Arrhenius parameters are determined for a
energy Ggas solvation ΔGsol temperature range between 298.15 K and 343.15 K. E: activation
a
energy [kJ mol-1], A: frequency factor [L mol-1 s-1], k: propagation
p
Solvent- rate coefficient at 298.15 K [L mol-1 s-1].
phase Gibss
free energy
Experimental Theoretical Theoretical
Gsol
w/o h-h effects w/ h-h effects
Figure 2: General flowchart of the applied methods and procedures E 20.7 20.7 19.7
a
in this work
log A 7.17 7.13 6.83
Once the Gibbs free energies are known for all reactants, k 4.06 103 3.20 103 2.36 103
p
products and transition states, they are used to determine the
Gibbs free activation energy ∆‡𝐺 and the Gibbs free reaction The obtained kinetic parameters for propagation of VAc can
energy ∆ 𝐺. These are then used to calculate the rate and be compared with experimental values through parity plots
𝑟
equilibrium coefficients based on standard textbook formulae (see Figure 4 and Figure 5). The first parity plot uses
[13, 17]: experimental values from Hutchinson et al. [19] obtained via a
pulsed-laser polymerization (PLP) experiment at a laser
𝑘 𝑇 −∆‡𝐺 (1) repetition rate of 100 Hz. These values are compared with ab
𝑘(𝑇)= 𝐵 𝑒 𝑅𝑇 initio rate coefficients including the head-to-head effects.
ℎ𝑐
0
−∆𝑟𝐺 (2) Whereas the second parity plot uses experimental values from
𝐾(𝑇)=𝑒 𝑅𝑇 Junkers et al. [20] obtained via a high frequency PLP
experiment at 500 Hz, whereby it is assumed that there is too
III. RESULTS AND DISCUSSION little time between the consecutive laser pulses for having a
significant amount of head-to-head additions. These values
A. Homopropagation of vinyl acetate are compared with the calculated values for the head-to-tail
The head-to-tail addition reaction of a dimer radical to a propagation. A reasonable agreement is obtained in both
vinyl acetate monomer was used as a model reaction for the cases.
computational study of the propagation of VAc. The
calculated kinetic parameters, together with experimental
values are shown in Table 1. It can be seen that the
propagation kinetics are accurately predicted.
It has been reported that the propagation rate of vinyl
acetate does not occur exclusively by head-to-tail additions,
but is significantly influenced by the frequent occurrence of
head-to-head additions [18]. When including the possibility of
head-to-head additions during propagation, the apparent
propagation rate coefficient is no longer determined solely by
the head-to-tail propagation rate, but is instead an averaged
composition of the four different types of propagation (see
Figure 3). The ab initio calculated kinetic parameters for
propagation of VAc, including head-to head effects are also

given in Table 1.
Figure 4: Parity plot comparing calculated values for the propagation
rate coefficient of VAc (including head-to-head effects) against
experimental values from Hutchinson et al. [19] (PLP-MWD at 100
Hz) for a temperature range between 283.15 K and 298.15 K
𝑓𝑟 +𝑓
𝑟̅ =𝑟′( 𝑖 𝑖 𝑗); 𝑖 ≠𝑗 𝑎𝑛𝑑 𝑖,𝑗=1 𝑜𝑟 2 (7)
𝑖 𝑖 𝑓𝑟′+𝑓
𝑖 𝑖 𝑗
𝑟𝑓 +𝑓
𝑘̅ =𝑘 ( 𝑖 𝑖 𝑗 ); 𝑖 ≠𝑗 𝑎𝑛𝑑 𝑖,𝑗=1 𝑜𝑟 2 (8)
𝑖𝑖 𝑖𝑖𝑖 𝑟𝑓 +𝑓⁄𝑠
𝑖 𝑖 𝑗 𝑖

These adjusted parameters are then used in Eq. (4)-(5) to
determine the instantaneous copolymer composition and the
copolymerization rate coefficient.
The ab initio calculated rate coefficients for all homo- and
crosspropagation reactions are given in Table 2.
Table 2: Calculated homo- and crosspropagation rate coefficients for
VAc/St copolymerization, evaluated in bulk VAc. 1: VAc, 2: St. E:
a
activation energy [kJ mol-1], A: frequency factor [L mol-1 s-1], k:
p
propagation rate coefficient at 298.15 K [L mol-1 s-1].
Figure 5: Parity plot comparing calculated values for the propagation
rate coefficient (not including head-to-head effects) against E log(A) k
a p
experimental values from Junkers et al. [20] (PLP-SEC at 500 Hz)
for a temperature range between 278 K and 343 K. lan kk11 1185..06 67..7727 31..7039 110035
B. Copolymerization of vinyl acetate and styrene imr k1222 30.8 7.30 8.02 101
et k 45.3 8.11 1.48 100
The copolymerization of VAc and St, has been evaluated 21
k 20.7 7.13 3.20 103
using both a terminal and a penultimate copolymerization 111
k 21.1 6.69 9.76 102
moFdoerl .t he terminal model, it is assumed that only the terminal eta k211112 15.9 7.57 6.21 104
m k 15.1 7.12 2.92 104
uthnei tr eaaffcetciotsn tshceh eremaec tiisv iatsy foofl ltohwe sp: ropagating chain radical and itlu k211222 35.9 7.62 2.14 101
ne k 31.2 7.27 6.38 101
p 222
k 43.3 7.55 9.37 10-1
121
Where index ‘1’ will be used to represent VAc and index k 44.2 7.58 6.93 10-1
221
‘2’ will be used to represent St.
For obtaining the rate coefficients k for the terminal model, It can be seen that there are penultimate effects, with homo-
ij
the radical addition reactions of unimer radicals are and crosspropagation rate coefficients with different
considered during the computational study. These rate penultimate units (e.g. k vs. k ) differing up to a factor 3.
112 212
coefficients are then used to determine the reactivity ratios r Based on the rate coefficients of Table 2, the necessary
1
and r (see Eq. (3)), which are then used to calculate the reactivity ratios were determined for the terminal model (Eq.
2
instantaneous copolymer composition F (Eq. (4)) [21] and the (3)-(5)) and for the penultimate model (Eq. (6)-(8)). These
i
copolymerization propagation rate coefficient 〈𝑘 〉 (Eq. (5)) reactivity ratios can then be used to predict the
𝑝
[22] as function of the monomer mixture composition f. copolymerization propagation rate <k > and the instantaneous
i p
𝑘 copolymer composition F as function of the monomer
𝑟 = 𝑖𝑖 𝑤ℎ𝑒𝑟𝑒 𝑖 ≠𝑗 𝑎𝑛𝑑 𝑖,𝑗=1 𝑜𝑟 2 (3) 1
𝑖 𝑘𝑖𝑗 mixture composition f1. This is visualized in Figure 5 and
𝐹 𝑓 𝑟 𝑓 +𝑓 Figure 6, respectively, for the theoretical terminal model
1 1 1 1 2
= (4) (green dash-dot curve), for the theoretical penultimate model
𝐹 𝑓 𝑟 𝑓 +𝑓
2 2 2 2 1 (blue dashed curve) and also for an experimental terminal
𝑟 𝑓2+2𝑓𝑓 +𝑟 𝑓2 model (red solid curve). For the experimental terminal model,
〈𝑘 〉= 1 1 1 2 2 2 (5)
𝑝 [𝑟 𝑓⁄𝑘 ]+[𝑟 𝑓⁄𝑘 ] r1= 0.05 and r2=50 [23] are used. Note that for both terminal
1 1 11 2 2 22
models, the values of k111 and k222 were used as k11 and k22 in
For the (explicit) penultimate copolymerization model, it is Eq. (7), as to have similar behavior of <kp> at f1=0 and f1=1.
assumed that there is also an influence by the penultimate unit It can be seen that both terminal and penultimate model give
on the propagation kinetics. The reaction scheme is then given similar predictions for the copolymerization propagation rate
as follows: coefficient and for copolymer composition. There is almost
exact agreement between the ab initio and experimental
terminal models.

In order to be able to account for the penultimate unit
effects during the computational study, the addition reactions
of dimer radicals are evaluated.
The penultimate propagation rate coefficients are used to
define four different monomer reactivity ratios r , r , r ’ and
1 2 1
r ’ and two radical reactivity ratios s and s (see Eq. (6)),
2 1 2
which are used to calculate the adjusted parameters 𝑟̅ and 𝑘̅ ,
𝑖 𝑖𝑖
as given in Eq. (7)-(8).

𝑘 𝑘 𝑘
𝑟 = 𝑖𝑖𝑖;𝑟′ = 𝑗𝑖𝑖;𝑠 = 𝑗𝑖𝑖 ;𝑖 ≠𝑗 𝑎𝑛𝑑 𝑖,𝑗=1 𝑜𝑟 2 (6)
𝑖 𝑘 𝑖 𝑘 𝑖 𝑘
𝑖𝑖𝑗 𝑗𝑖𝑗 𝑖𝑖𝑖
Figure 6: Copolymerization propagation rate coefficient <kp> as a
function of VAc mole fraction of the monomer mixture, f1.
Theoretical terminal model predictions (green dash-dot curve),
Theoretical penultimate model (blue dashed curve), experimental Figure 8: The two-stage synthesis of poly(St)-block-poly(VAc) using
terminal model (red solid curve). the switchable RAFT agent PMDTC.
First, the effect of protonation of PMDTC on the addition-
fragmentation kinetics will be investigated by evaluating the
chain transfer sequence of a styryl radical (St•) with PMDTC.
The Gibbs free energy diagram is shown in Figure 9. I•
represents a cyanoisopropyl radical, T’-I represents the
protonated PMDTC RAFT agent and T-I represents the
deprotonated PMDTC RAFT agent.

Figure 7: Instantaneous copolymer VAc composition F as a function
1
of VAc mole fraction of the monomer mixture, f . Theoretical
1
terminal model predictions (green dash-dot curve), Theoretical
penultimate model (blue dashed curve), experimental terminal model
(red solid curve).

C. Switchable RAFT block copolymerization
Figure 9: Gibbs free energy diagram for the chain transfer sequence
Conventional RAFT agents are capable of controlling the of a styryl radical with the non-protonated PDMTC RAFT agent (T-
polymerization of either MAMs (e.g. methyl acrylate (MA), I, black) and the protonated PMDTC RAFT agent (T’-I, blue). The
Gibbs free energy [kJ mol-1] is determined relative to the reactants, at
St) or LAMs (e.g. N-vinyl pyrrolidone (NVP), VAc), but not
298.15 K.
both at the same time. A consequence is that the synthesis of
narrow polydispersity polyMAM-block-polyLAM using The protonation causes a significant stabilization of the
conventional RAFT agents is difficult or not possible at all. intermediate adduct radical, which leads to a lower reaction
However, this limitation can be overcome using so-called barrier for the addition reactions, which is necessary for a
switchable RAFT agents, which, upon external stimulus, can sufficiently fast addition rate of MAMs, such as St. However,
change their electronic properties to control the this stabilization of the intermediate adduct radical also causes
polymerization of either LAMs or MAMs [24]. One such a higher reaction barrier for fragmentation. This can become
switchable RAFT agent, which has been used used for the problematic during the controlled polymerization of LAMs,
synthesis of poly(St)-block-poly(VAc) [25], is PMDTC, such as VAc, since these already are relatively poor homolytic
whereby the switching happens by protonation/deprotonation leaving groups. Therefore, it is necessary to use the
of the RAFT agent. The synthesis of poly(St)-block- deprotonated PMDTC as RAFT agent during the
poly(VAc) happens in two stages (see Figure 8). First, there is polymerization of VAc.
a conventional RAFT polymerization of St, with protonated The first stage of the two-stage synthesis of poly(St)-block-
PMDTC as controlling agent. Once this polymerization is poly(VAc), where polymerization of St is controlled by
complete, the resulting poly(St) macro-RAFT agents are protonated PMDTC, is studied under the assumptions of a
isolated and deprotonated. This deprotonated poly(St) macro- terminal model, i.e. only the effects of the terminal unit of the
RAFT agent is then used for the second stage, to control the propagating radical on the addition-fragmentation reactions
subsequent polymerization of VAc. are taken into consideration. The transfer coefficients (𝐶 =
𝑡𝑟,0
14.0, 𝐶 = 0.004 and 𝐶 = 240.0) confirm that protonated
−𝑡𝑟,0 𝑡𝑟
PMDTC is an effective controlling agent for the RAFT degree of polymerization and polydispersity under various
polymerization of St. conditions.
In the investigation of the second stage of the block-
copolymerization, where VAc is polymerized with the
poly(St) macro-RAFT agent, two different approaches were
used. Firstly, a terminal model was assumed, whereby the
addition-fragmentation reactions were modeled with unimer
radicals. However, it was not possible to confirm the
effectiveness of the RAFT agent based on the obtained results
as the rate coefficients of addition of the vinyl acetate radical
were too low in comparison to the rate coefficients of
propagation. Furthermore, an investigation of the effect of
head-to-head additions on the addition-fragmentation
reactions was also performed, which showed that the
activation energy for fragmentation of the inverted vinyl
acetate ‘tail’ radical is about 20 kJ mol-1 higher than that for
the fragmentation of the normal ‘head’ radical. This could
lead to difficulties during the control of the polymerization,
whereby a fraction of the growing chains get stuck in the
dormant state and there is retardation of the reaction, a
phenomenon which has been experimentally observed [26,
27].
Secondly, a penultimate model was assumed, whereby the
addition-fragmentation reactions were modeled with dimer
radicals. There was a significant increase of the addition rate
coefficient of the vinyl acetate radicals to the RAFT agent
when the penultimate vinyl acetate unit was included in the
model reactions. This increase is attributed to a stabilizing
interaction between the methyl hydrogen of the penultimate
vinyl acetate unit and the pyridinyl nitrogen (see Figure 10),
which causes a stabilization of the intermediate adduct radical
and leads to an increased rate coefficient of addition. Figure 11: Ab initio based kinetic model simulations of the
However, the calculated transfer coefficients (𝐶 = 2.63 10-1 conversion vs. time (top), number-averaged chain length vs.
𝑡𝑟,0
and 𝐶 = 1.17 10-1) are still two orders of magnitude lower conversion (middle) and polydispersity vs. conversion (bottom)
𝑡𝑟
than the value reported by the experimental study of Keddie et compared with experimental data under various conditions. Left:
𝑎𝑝𝑝 Temperature of 343.15 K, Targeted chain length (TCL) of 200, Ratio
al. [27] (𝐶 = 41.7).
𝑡𝑟 of RAFT agent over initiator (CTA/AIBN) of 2:1. Right:
Temperature of 353.15 K, TCL of 50 and CTA/AIBN of 2:1.
IV. CONCLUSIONS
Several polymerization systems were investigated by a
computational study and accurate kinetic parameters based on
ab initio calculations were obtained. On the one hand, this
allowed the evaluation of the influence of possible side
reactions, e.g. head-to-head additions of vinyl acetate, as well
as the influence of the penultimate unit effects, e.g. in the
copolymerization of styrene with vinyl acetate.
On the other hand, these parameters can be successfully
used in a kinetic model, as demonstrated in the simulation of
the RAFT polymerization of styrene with CPDT.

Figure 10: Optimized molecular geometry of (VAc-VAc-T-VAc)•, REFERENCES
highlighting the stabilizing interaction of the penultimate unit with [1] K. Matyjaszewski, T.P. Davis, Handbook of radical polymerization,
the pyridinyl nitrogen. Wiley Online Library, 2002.
[2] M. Destarac, Controlled Radical Polymerization: Industrial Stakes,
Obstacles and Achievements, Macromolecular Reaction Engineering, 4
D. Kinetic modeling of RAFT polymerization of styrene
(2010) 165-79.
The kinetic parameters of the addition-fragmentation [3] F. Chauvin, A.M. Alb, D. Bertin, P. Tordo, W.F. Reed, Kinetics and
reactions for the RAFT polymerization of styrene with CPDT molecular weight evolution during controlled radical polymerization,
Macromolecular Chemistry and Physics, 203 (2002) 2029-41.
as RAFT agent and AIBN as initiator have been determined
[4] A. Gregory, M.H. Stenzel, Complex polymer architectures via RAFT
by computational chemistry and were implemented into a polymerization: From fundamental process to extending the scope using click
kinetic model. The results of these ab initio based kinetic chemistry and nature's building blocks, Progress in Polymer Science, 37
model simulations were compared with experimental (2012) 38-105.
[5] C. Barner-Kowollik, Handbook of RAFT polymerization, John Wiley &
measurements (e.g. for different temperatures, see Figure 11).
Sons, 2008.
The simulations managed to correctly predict conversion,
[6] M. Chen, K.P. Ghiggino, A. Launikonis, A.W.H. Mau, E. Rizzardo,
W.H.F. Sasse, S.H. Thang, G.J. Wilson, RAFT synthesis of linear and star-
shaped light harvesting polymers using di-and hexafunctional ruthenium
polypyridine reagents, Journal of Materials Chemistry, 13 (2003) 2696-700.
[7] M. Chen, K.P. Ghiggino, A.W.H. Mau, E. Rizzardo, W.H.F. Sasse, S.H.
Thang, G.J. Wilson, Synthesis of functionalized RAFT agents for light
harvesting macromolecules, Macromolecules, 37 (2004) 5479-81.
[8] A.E. Smith, X. Xu, S.E. Kirkland-York, D.A. Savin, C.L. McCormick,
“Schizophrenic” Self-Assembly of Block Copolymers Synthesized via
Aqueous RAFT Polymerization: From Micelles to Vesicles†† Paper number
143 in a series on Water-Soluble Polymers, Macromolecules, 43 (2010) 1210-
17.
[9] Y.Q. Hu, M.S. Kim, B.S. Kim, D.S. Lee, Synthesis and pH-dependent
micellization of 2-(diisopropylamino)ethyl methacrylate based amphiphilic
diblock copolymers via RAFT polymerization, Polymer, 48 (2007) 3437-43.
[10] G. Moad, E. Rizzardo, S.H. Thang, RAFT polymerization and some of
its applications, Chemistry–An Asian Journal, 8 (2013) 1634-44.
[11] G. Moad, M. Chen, M. Häussler, A. Postma, E. Rizzardo, S.H. Thang,
Functional polymers for optoelectronic applications by RAFT polymerization,
Polymer Chemistry, 2 (2011) 492-519.
[12] B.B. Noble, M.L. Coote, First principles modelling of free-radical
polymerisation kinetics, International Reviews in Physical Chemistry, 32
(2013) 467-513.
[13] V. Van Speybroeck, K. De Wispelaere, Moleculaire Modellering van
Industriële Processen [Course], Ghent University, 2013.
[14] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R.
Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, 09,
Revision D. 01, Gaussian, Inc., Wallingford, CT, (2009).
[15] R.F. Ribeiro, A.V. Marenich, C.J. Cramer, D.G. Truhlar, Use of
Solution-Phase Vibrational Frequencies in Continuum Models for the Free
Energy of Solvation, The Journal of Physical Chemistry B, 115 (2011) 14556-
62.
[16] A. Klamt, F. Eckert, M. Hornig, COSMO-RS: A novel view to
physiological solvation and partition questions, J Comput Aided Mol Des, 15
(2001) 355-65.
[17] V. Van Speybroeck, M.F. Reyniers, Chemistry of Industrial Processes,
Partim V. Van Speybroeck [Course], Ghent University, 2014.
[18] O. Monyatsi, A.N. Nikitin, R.A. Hutchinson, Effect of Head-To-Head
Addition on Vinyl Acetate Propagation Kinetics in Radical Polymerization,
Macromolecules, 47 (2014) 8145-53.
[19] R.A. Hutchinson, J.R. Richards, M.T. Aronson, Determination of
propagation rate coefficients by pulsed-laser polymerization for systems with
rapid chain growth: vinyl acetate, Macromolecules, 27 (1994) 4530-37.
[20] T. Junkers, D. Voll, C. Barner-Kowollik, Determination of vinyl acetate
propagation rate coefficients via high frequency pulsed laser polymerization,
e-Polymers, 9 (2009) 931-38.
[21] F.R. Mayo, F.M. Lewis, Copolymerization. I. A basis for comparing the
behavior of monomers in copolymerization; the copolymerization of styrene
and methyl methacrylate, Journal of the American Chemical Society, 66
(1944) 1594-601.
[22] T. Fukuda, Y.D. Ma, H. Inagaki, Free-radical copolymerization. 3.
Determination of rate constants of propagation and termination for
styrene/methyl methacrylate system. A critical test of terminal-model
kinetics, Macromolecules, 18 (1985) 17-26.
[23] J.B.a.E. Immergut, Polymer Handbook, International Science, Wiley,
New York, (1989).
[24] M. Benaglia, J. Chiefari, Y.K. Chong, G. Moad, E. Rizzardo, S.H.
Thang, Universal (switchable) RAFT agents, Journal of the American
Chemical Society, 131 (2009) 6914-15.
[25] M. Benaglia, M. Chen, Y.K. Chong, G. Moad, E. Rizzardo, S.H. Thang,
Polystyrene-block-poly (vinyl acetate) through the Use of a Switchable RAFT
Agent, Macromolecules, 42 (2009) 9384-86.
[26] M. Destarac, D. Charmot, X. Franck, S.Z. Zard, Dithiocarbamates as
universal reversible addition‐fragmentation chain transfer agents,
Macromolecular Rapid Communications, 21 (2000) 1035-39.
[27] D.J. Keddie, C. Guerrero-Sanchez, G. Moad, R.J. Mulder, E. Rizzardo,
S.H. Thang, Chain transfer kinetics of acid/base switchable N-aryl-N-pyridyl
dithiocarbamate RAFT agents in methyl acrylate, N-vinylcarbazole and vinyl
acetate polymerization, Macromolecules, 45 (2012) 4205-15.