The current state-of-the-art strategy formaking polymer colloids usually employsradical-initiated emulsion or miniemulsionpolymerization. Despite its success, it haslimitations: This strategy only works well with a
limited number of monomers such asacrylates, methacrylates, and styrenics.
It will break the double bonds ofmonomers, leaving no unsaturation in thepolymer backbone (typically only sidegroups can be used for furtherfunctionalization).
We challenged ourselves to address theseissues via introducing metathesis chemistryinto the preparation of polymer colloids.
Background
Catalyst design
(a) Further investigate the reactivity, efficiency and partitioning behavior of catalyst;
(b) Deepen the understanding of kinetics in miniemulsion polymerization including nucleation, chain propagation, chain transfer, etc.;
(c) Introduce new monomers.
Experimental
Future Work
Motivation
Experimental
Polymer Latexes via Ring-opening Metathesis Polymerization (ROMP)
Chunyang Zhu1, Xiaowei Wu2, Cathleen M. Crudden2, Michael F. Cunningham1,2
1. Department of Chemical Engineering, Queen’s University, Kingston, Ontario, Canada, K7L 3N62. Department of Chemistry, Queens’s University, Kingston, Ontario, Canada, K7L 3N6
[1] Hong, S. H., & Grubbs, R. H. (2006).Journal of the American Chemical Society,128(11), 3508–9.
Ontario Research Chairs Program
Why ring opening metathesis polymerization (ROMP)?
Traditional radical polymerization methodsresult in a reduction in functionality (alkenesto alkanes). In contrast, ROMP retains all ofthe functionality of the starting olefins,which allows potential applications in manyfields such as biomaterials, liquid crystallinepolymers, self-healing materials, degradableplastics, and nanocomposites.
How does ROMP work in the aqueous phase?
Current ROMP is typically employed inorganic solvents since the catalysts arehydrophobic and have limited long-termstability in water.[1] Here we developed anovel ROMP process in aqueous dispersionswhich eliminates the use of organic solventsand enhances heat transfer and mixing. Thisnew process is based on our modifiedcatalysts. The development is believed toachieve three objectives:
(a)Enabling the preparation of latexes viaROMP, which is currently not possible inindustry;
(b)Eliminating the use of large amounts ofvolatile organic compounds (VOCs);
(c) Improving the efficiency and lowering thecost of the manufacturing process.
(a) A novel water-soluble metathesis catalyst was customized for miniemulsion polymerization.
(b) A procedure was developed for ring opening metathesis polymerization in miniemulsion.
(c) Well-defined polymer latexes were obtained with stable colloidal behavior and particle size, which can be used as intermediates for further modification.
After shaking
Solubility Stability Reactivity
1H NMR of new catalyst (D2O) 1H NMR of ROMP (CD2Cl2)
Kinetic study
LnMR
metalalkylidene
+
LnMR
[2+2]LnM
RLnM R
metallacyclobutane
LnM R + n LnM Rn+1
LnM Rn+1
+ X=Y LnM=X Y Rn+1
+
Initiation:
Propagation:
Termination:
𝑅𝑅𝑝𝑝 = −𝑑𝑑 𝑀𝑀𝑑𝑑𝑑𝑑 = 𝑘𝑘𝑝𝑝 𝑅𝑅𝑅𝑅 𝑀𝑀
ln𝑀𝑀 0
𝑀𝑀 𝑡𝑡= ln
11 − 𝑥𝑥
= 𝑘𝑘𝑝𝑝 𝑅𝑅𝑅𝑅 𝑑𝑑
Preparation of monomer miniemulsion
HD/COD/Triton-X100/H2O
Time (min)
0 10 20 30 40 50 60 70
Z-av
g (d
. nm
)
50
100
150
200
250
PDI
0.0
0.1
0.2
0.3
0.4
0.5
HD/COD/CTAB/H2O
Time (min)
0 10 20 30 40 50 60 70
Z-av
g (d
. nm
)
60
80
100
120
140
160
180
200
PDI
0.0
0.1
0.2
0.3
0.4
0.5
HD/NB/Triton-X100/H2O
Time (min)
0 10 20 30 40 50 60 70
Z-av
g (d
. nm
)
50
100
150
200
250
PDI
0.0
0.1
0.2
0.3
0.4
0.5
HD/NB/CTAB/H2O
Time (min)
0 10 20 30 40 50 60 70
Z-av
g (d
. nm
)
60
80
100
120
140
160
180
200
PDI
0.0
0.1
0.2
0.3
0.4
0.5
LogM
3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4
d(w
t)/d(
LogM
)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Conversion
0.0 0.2 0.4 0.6 0.8 1.0
Mn
0
10000
20000
30000
40000
50000
60000
PDI
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4t = 1 hrt = 2 hrt = 3 hr t = 4 hrt = 5 hrt = 7 hr t = 12 hr
ROMP in miniemulsion
Ar
Ar
H2O/Surfactant
Monomer/costabilizer
Ar
Monomer miniemulsion
Sonication Catalyst
Ar
Polymer latex
cannula
cannula
Monomer emulsion
Time (hr)
0 20 40 60 80
Z_av
g (n
m)
100
120
140
160
180
200
PDI
0.0
0.1
0.2
0.3
0.4
0.5
Discussion
References
ROMP of 1,5-cyclooctadine in CD2Cl2 using the new catalyst.
Evolution of molecular weight and PDI with conversion(solution polymerization).
Z-average diameter and PDI values of various monomer miniemulsions.
ROMP in miniemulsion with air-free technique.
Evolution of MWD, Mn and PDI with reaction time (miniemulsion polymerization).
Z-average diameters during polymerization.
[Ru]n
n
Time (hr)
0 20 40 60 80
Conv
ersio
n
0.0
0.2
0.4
0.6
0.8
1.0
Time (hr)
0 20 40 60 80
ln[1
/(1-x
)]
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Conversion
0.0 0.2 0.4 0.6 0.8
Mn
0.0
2.0e+4
4.0e+4
6.0e+4
8.0e+4
1.0e+5
1.2e+5
PDI
0
1
2
3
4
MnTarget MnPDI
LogM
3.5 4.0 4.5 5.0 5.5 6.0 6.5
dwt/d
LogM
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4 60 h48 h36hr24 h12 h
Conversion and normalized conversion plots with time (miniemulsion polymerization).
O
O
OOHO
ON
N
BrO
O
O
Prof. CruddenProf. Cunningham Chunyang ZhuDr. Wu