Our work in this area is mostly related to catalytic polymerization. With this method in hand, we can prepare functional polyethylene, polyethylene nanoparticles or functional insertion polynorbornenes




Videos where our work is exposed


We are interested in the following reaction in wich F is a polar functionality (ester, amide, etc...):


Our work is centered around palladium phosphine sulfonates as catalysts. Over the years, a catalyst platform has been developed using such phosphines which are more or less electron-rich and with various steric hindrance. Some of these catalysts have been crystallized, revealing that these complexes all adopt a square planar geometry whereby an ancillary Lewis base (lutidine, eg) is trans to the phosphine and the methyl group trans to the sulfonate..

phosphine sulfonate Pd catalysts

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A variety of polar monomers have been inserted in the polymer with these catalysts, thus highlighting the high versatility of such catalsyts. In all cases, the polymers are linear, with insertion contents which are most often low (up to 10 mol%) and with moderate molecular weights. .

polar comonomers
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The insertion of polar monomers along the polyethylene chain change the properties of the material. For example, with a few percent of N-isopropyl acrylamide, the surface of the polyethylene becomes hydrophilic, as shown by the contact angle measurements below.

hydrophilic polyethylene


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Sulfonic acid groups have been inserted along the polyethylene chain, leading to the formation of sulfonated ionomers. Their properties as proton exchange membranes for fuel cells have been evaluated. This work was performed in collaboration with the group of Professor Ana Tavare at INRS-EMT.


polyolefine fuel cell


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Furthermore, polymers with a reversibly switchwable crystallinity activated by a chemical stimulus have been prepared. In the presence of gazeous hydrazine or ozone, the polyethylene switches for amorphous to crystalline. 

smart polyethylene


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Emulsion polymerization is usually confined to radical polymerization in aqueous medium. Only a few examples of anionic, cationic and catalytic polymerizations have been performed in aqueous emulsion. This is of course due to to the reactivity of water toward carbocations, carbanions and organometallic complexes. We have been interested in performing catalytic polymerizations in aqueous emulsion. Polyolefins such as polyethylene and polypropylene are commodity polymers which are prepared on a very large scale (approx 100 million tons per year). We could envisage that the preparation of aqueous emulsions of polyolefins could open the way to a new class of materials. We discovered by serendipity a polymerization catalyst which has a homopolymerization activity greater than 2,000,000 g/g/h. This catalyst is a neutral Nickel phospholyide which belongs to the family of Shop catalysts unrabelled by Prof. Keim. We initially used this catalyst to prepare polyolefins in aqueous emulsion.

cata Keim

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Using this catalyst, it is possible to polymerize ethylene in water. As the reaction occurs in water, the activity is much lower than in organic medium, and reaches at best 10,000 g/g/h (P = 20 bars, T = 55 oC). Even in the presence of surfactant, the product is not colloidaly stable. Here is a picture of such product (ie a dispersion which is not colloidaly stable).

latex PE

By using a miniemulsion process, it is however possible to increase colloidal stability and to generate a stable latex of polyolefin. On the right, this is a picture of a HDPE latex, and on the left, the transmission electron microscopy (TEM) picture of this latex. Note how the surface of these nanoparticles is irregular: this is due to the high crystallinity of HDPE.

Latex polyethylene miniemulsion
Left: Latex of HDPE
Right : TEM of the latex particles(average size : 30 x 200 nm)
the rugged shape is ascribed to the crystallinity
TEM PE latex

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Several monomers, polar and non-polar, have been copolymerized with ethylene in emulsion. The insertion of such comonomers results in a decrease of the crystallitiy. The particles become spherical and tacky. The colloidal stability is also greatly improved. Due to the confinement of the comonomer within the growing polymer particles (compartimentalization effect) the insertion of the comonomer is favored. Thus, using Pd catalysts, polar monomers such as acrylates have been copolymerized with ethylene in emulsion, leading to the formation of very interesting latexes. They have a low crystallinity, and therefore they easily form films, they adhere to many surfaces, and they are very hydrophobic.  

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These latexes can be used to prepare films, in the same manner that acrylic latexes are used in aqueous paints. These very hydrophobic latexes have promising properties for the protection against corrosion, as shown below with a standard corrosion test performed with a Qfog salt box. The aging of the coating was followed by electrochemical impedance spectroscopy.

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Unique polyethylene nanoparticles can be prepared. This is, for example, the case for poly(ethylene-co-acrylic acid) nanoparticles. In collaboration with Prof. Françoise Winnik, from University of Montreal, we have shown that these nanoparticles are thermoreversible.

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In order to explain why these nanoparticles are thermoreversible, a modeling work has been performed in collaboration with Prof. Armand Soldera. This work has highlighted the pivotal role played by the surface tension energy of lateral faces in the formation of polyethylene nanocrystals dispersed in water.

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Recently, in collaboration withprofessor Zetterlund of the University of New South-Wales in Australia, we have shown that a mixture of supercritical CO2 and water constitutes an ideal environment to prepare such nanoparticles via an emulsion polymerization process



Insertion polynorbornene (PNBE) is a remarkable polymer. It combines excellent thermomechanical properties (Tg higher than 300 oC), a good chemical resistance, a high transparency and a low dielectric constant. Its properties are very different from those of PNBE obtained by ring-opening metathesis polymerization (ROMP).

There exists a large number of catalysts for the synthesis of insertion PNBE. They lead to polymers with various tacticities. In the absence of substituent, PNBE is very difficult to process. Thus, it is necessary to polymerize functional norbornene monomers in order to facilitate processing. Unfortunatly, the polymerization of functional monomers with an endo substituent is very difficult, as shown in the table below.

The polymerization of functional norbornenes is difficult, due to the lack of reactivity of endo isomers. We have searched the reasons underlying this lack of reactivity, and we found that with a cationic Pd catalyst, two endo monomers cannot be inserted in a row. However, the catalyst can promote the isomerization of the endo monomer to exo (via a Diels-Alder reaction). Thanks to this new mechanism, it is possible to polymerize a large number of fonctional norbornenes without need to separate endo norbornene from exo one.

This work was illustrated in the inside cover of Chemical Science. We can see an endo monomer isomerized into exo before being polymerized.

Starting from these PNBE, epoxy thermoset resins which are free of bisphenol, and with very high Tg (up to 350 oC) have been prepared. Besides their high Tg, the thermoset resins have very good mechanical properties (modulus up to 6 GPa, coefficient of thermal expansion lower as low as 50 ppm at 300 oC) and a high chemical stability (stable to acid, no decomposition before 350 oC). Furthermore, PNBE can be used as epoxy monomer which is then cross-linked (hardened) with biosourced and cheap hardeners such as glycerol, or, alternatively, they can be used as hardeners of biosourced epoxy monomers. Thus, it is possible to prepare highly-biousourced epoxy resins which are free of bisphenol and epichlorhydrin, and which have a very high Tg.