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A polymeric catalytic membrane was previously prepared that showed remarkable efficiency for Suzuki-Miyaura C-C cross-coupling in a flow-through configuration. A mathematic model was developed and fitted to the experimental data to understand the significant apparent reaction rate increase exhibited by the catalytic membrane reactor compared to the catalytic system under batch reaction conditions. It appears that the high palladium nanoparticles concentration inside the membrane is mainly responsible for the high apparent reaction rate achieved. In addition, the best performance of the catalytic membrane could be achieved only in the forced flow-through configuration, that, conditions permitting to the reactants be brought to the catalytic membrane by convection. © 2016 American Institute of Chemical Engineers AIChE J, 63: 698–704, 2017

International audience; The elaboration of a polymeric catalytic membrane containing palladium nanoparticles is presented. The membrane was prepared using a photo-grafting process with imidazolium-based ionic liquid monomers as modifying agent and microPES® as support membrane. Ionic liquid serves as a stabilizer and immobilizer for the catalytic species, i.e. palladium nanoparticles. The Suzuki–Miyaura cross-coupling reaction was carried out on the catalytic membrane in flow-through configuration. Complete conversion was achieved in 10 s through one single filtration, without formation of byproducts. The apparent reaction rate constant was three orders of magnitude greater than in a batch reactor. No catalyst leaching was detected. This membrane offers the possibility of continuous production with no need for a separation step of the catalyst from the reaction medium.

Poly(1,4-phenylenevinylene) (PPV), a perfectly alternating copolymer of p-phenylene and trans-vinylene units, possesses attractive material properties. Thin films of PPV display high electrical conductivity when doped (σ = 5000 S/cm), a large, third-order nonlinear optical response (χ^3 = 1.5 X 10^(-10) esu), and photo- and electroluminescence in the visible region. However, the extended planar topology of the PPV backbone, which renders it infusible and insoluble in nonreactive media, limits the capacity for post-synthesis fabrication of the material. A convenient method to circumvent this problem consists of a two-step synthesis via a processable intermediate polymer. This precursor polymer can be fabricated into the desired form and subsequently converted to the target polymer by a clean, intramolecular chemical reaction. Wessling and Zimmerman have reported the synthesis of a processable, water-soluble poly(l,4-xylylenesulfonium salt) that undergoes a thermally-induced elimination to PPV under mild conditions.

Poly(p-phenylene) (PPP) is an insoluble rigid-rod polymer that possesses remarkable thermal stability, chemical resistance, and electrical conductivity when doped. The structural properties that make PPP such an attractive engineering material also make it difficult to synthesize and process. Direct synthetic approaches have given either ill-defined material with a mixture of para, meta, and ortho linkages and crosslink or insoluble oligomers. Precursor strategies to PPP have been devised in which the synthetic and processing difficulties of the direct methods have been overcome through the use of a soluble intermediate polymer. The most successful of the precursor strategies was developed at ICI by Ballard et al. This process involves the radical polymerization of the bis(acetyl) or bis(methoxycarbonyl) derivatives of cis-5,ddihydroxy- 1,3-cyclohexadiene (l), a microbial oxidation product of benzene. The resulting polymers are subsequently aromatized to yield PPP by thermally induced acid elimination. This process, however, yields only phenylene oligomers due to fracturing of the precursors during pyrolysis. Fracturing is believed to arise from the 90% 1,4-linkages, 10% 1,2-linkages, and random stereochemistry along the precursor backbones which result from the nonstereospecific nature of the radical polymerization. A route to 100% 1,4-linked PPP precursors with the correct stereochemistry for facile cis-pyrolytic elimination of the pendant groups has been developed which combines the efficiency and processability of the ICI process with the regio- and stereochemical control possible through transition-metal catalysts (Scheme I).