MODEL-BASED DESIGN OF REACTION CONDITIONS FOR

SEGMENTED COPOLYMER SYNTHESIS BY COMBINING

STEP- AND CHAIN-GROWTH POLYMERIZATION

Lies De Keer,1 Thomas Gegenhuber,3 Paul H.M. Van Steenberge,1 Anja S. Goldmann,3

Marie-Françoise Reyniers,1 Christopher Barner-Kowollik,2,3 Dagmar R. D’hooge1,4

67TH CANADIAN CHEMICAL ENGINEERING CONFERENCE, EDMONTON, 22-25 OCTOBER 2017

1Laboratory for Chemical Technology (LCT), Ghent University

2School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT)

3Preparative Macromolecular Chemistry, Karlsruhe Institute of Technology (KIT)

4Centre for Textile Science and Engineering (CTSE), Ghent University

POLYMER CONJUGATION

Functional groups within polymer backbone:

Conjugation of macromolecular building blocks

Applications: e.g. introducing automated degradability in polymer chains

Research questions:

• adjustable segment length?

• synthesis strategy?

• reaction conditions ?

=> model-based design

2 PHASE SYNTHESIS STRATEGY

bifunctional ortho-methyl

benzaldehyde (AA)

bisfumarate bearing a

trithiocarbonate group (BB)

2) Chain-growth polymerization:

RAFT polymerization

1) Step-growth polymerization:

light-induced Diels-Alder reaction

MULTI-SCALE MODELING STRATEGY

D’hooge D.R. et al. Prog. Polym. Sci. 2016 58, 59

Derboven et al. Macromolecules 2015, 48, 492D’hooge et al. Macromol. React Eng. 2013, 7, 362

SOLUTION METHODS

5 5

Chain position (-)

Macromolecular structural detail

Model com

ple

xity

Van Steenberge P.H.M. et al. Macromolecules 2011, 44, 8716

Van Steenberge P.H.M. et al. Macromolecules 2012, 45,8519.

Van Steenberge P.H.M. et al. Chem. Eng. Sci. 2014, 11, 185

D’hooge D.R. et al. Polym. Chem. 2015, 6, 7081.

Derboven P. et al. Macromol. Rapid Commun. 2015, 36, 2149

D’hooge D.R. et al. Prog. Polym. Sci. 2016, 58, 59

Chain

num

ber

(-)

Log (molar mass)

w(l

ok

gm

ola

rm

ass

)

KINETIC MONTE CARLO METHOD

Composite binary trees

Van Steenberge P.H.M. et al. Chem. Eng. Sci. 2014, 11, 185 Brandao A.L.T. et al. Macromol. React Eng. 2015, 9, 141

OUTLINELight-induced step-growth polymerization

Experimental observations

Theoretical framework

Rate coefficients in view of design

Design step-growth precursor toward high molar masses

Chain extension by RAFT polymerization

Experimental observations

Theoretical framework

Rate coefficients in view of design

Design toward microstructural control

Conclusions

EXPERIMENTAL OBSERVATIONS

photoenolR = H, Ph

Gegenhuber et al. Macromolecules 2017 50, 6451

Main:

Monomer stability

Side:

THEORETICAL FRAMEWORK AND RATE COEFFICIENTS

kmain via small molecule study

ModelExperiment

kself,AA via monomer stability test

Experiment Model

r = 𝑁𝐴,0

𝑁𝐵,0

DESIGN STEP-GROWTH PRECURSOR TOWARD HIGH MOLAR MASSES[AA]0=[BB]0=0.02 mol L-1Equimolar conditions, r =

𝑁𝐴,0

𝑁𝐵,0= 1

No high molar mass chains

𝑋𝑤 =1 + 𝑝𝐴1 − 𝑝𝐴

[AA]0=0.07 mol L-1; [BB]0=0.02 mol L-1Off-stoichiometric conditions, r = 𝑁𝐴,0

𝑁𝐵,0= 1.75

𝑋𝑤 =1 +

1𝑟(1 + 𝑝𝐴)

1 +1𝑟−2𝑟𝑝𝐴

DESIGN STEP-GROWTH PRECURSOR TOWARD HIGH MOLAR MASSES

Incorporation of AA homopolymer

after depletion of BB

Longer AA homopolymer chains if excess of AA

Stage 1

Stage 2

r >> 1BBAA

r = 1BBAA

DESIGN STEP-GROWTH PRECURSOR TOWARD HIGH MOLAR MASSES

DESIGN STEP-GROWTH PRECURSOR TOWARD HIGH MOLAR MASSES

OUTLINELight-induced step-growth polymerization

Experimental observations

Theoretical framework

Rate coefficients in view of design

Design step-growth precursor toward high molar masses

Chain extension by RAFT polymerization

Experimental observations

Theoretical framework

Rate coefficients in view of design

Design toward microstructural control

Conclusions

EXPERIMENTAL OBSERVATIONS

Segmented copolymer

• solubility

• still copolymer

• time for pA

Precursor copolymer

6 h

Bivariate

(1) chain length

(2) # RAFT moieties

THEORETICAL FRAMEWORK

12 dormant chain types, 7 radical types, > 200 reactions

Step-growth polymer precursor for r = 𝑁𝐴,0

𝑁𝐵,0= 1.5

[Styrene]0=8.74 mol L-1

[AIBN]0=4.85 10-3 mol L-1

Step-growth polymer precursor for r = 𝑁𝐴,0

𝑁𝐵,0= 1

[Styrene]0=8.74 mol L-1

[AIBN]0=4.85 10-3 mol L-1

RATE COEFFICIENTS IN VIEW OF DESIGN

Step-growth precursor Xstyrene = 1 %

Xstyrene = 6 %Xstyrene = 3 % Incorporation of styrene

RAFT groups well-located

Chain extension ~ # RAFT

r = 𝑁𝐴,0

𝑁𝐵,0= 1.5

DESIGN TOWARD MICROSTRUCTURAL CONTROL

Multisegment copolymers with on average 70 monomer units per segment

OUTLINELight-induced step-growth polymerization

Experimental observations

Theoretical framework

Rate coefficients in view of design

Design step-growth precursor toward high molar masses

Chain extension by RAFT polymerization

Experimental observations

Theoretical framework

Rate coefficients in view of design

Design toward microstructural control

Conclusions

CONCLUSIONS

Step-growth polymerization of benzaldehyde and fumarate monomers containing

a trithiocarbonate RAFT moiety employing light-induced Diels Alder chemistry is

introduced.

Unconventional off-stochiometric conditions necessary to compensate for the

unavoidable homopolymerization of the benzaldehyde monomer.

The step-growth precursor polymer is successfully employed as a multifunctional

CTA for RAFT polymerization, leading to a well-defined segmented copolymer.

Polymer synthesis and advanced kinetic modeling strategies are combined to

identify optimal synthetic conditions and to predict their structural composition.

ACKNOWLEDGMENTS

Fund for Scientific Research Flanders (FWO; 1S37517N)

Karlsruhe Institute of Technology, KIT, Germany: STN and BIFTM

Queensland University of Technology, Australia

Australian Research Council

Baden-Wuerttemberg Stiftung

Elite Network Bavaria

LABORATORY FOR CHEMICAL TECHNOLOGY

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https://www.lct.ugent.be