Depolymerizable Polyimines Triggered by Heat or Acid as Binders for Conductive Inks

The ability to print electronic devices on soft substrates has the potential to revolutionize the world of consumable electronics. Electronic inks are typically constituted of an active nanomaterial dispersed in a solvent and stabilized by a surfactant which is necessary to impart colloidal stability. However, once the ink is applied, the surfactant presence in the final product is detrimental to the device performance. Here, we report the preparation of polyimines that can depolymerize and evaporate in the presence of light and heat. These polyimines were used for the formulation of Ag nanoparticle inks as well as for the dispersion of multiwalled carbon nanotubes (MWCNTs). In both cases, stable dispersions were obtained and were applied on a variety of substrates, leading to low-conductivity inks. However, the depolymerization and evaporation of the polyimine surfactant could be triggered by light and heat, then leading to a high-conductivity ink. By use of a laser engraver equipped with a CO2 laser, it was possible to spatially control the depolymerization of the MWCNT ink applied on a poly­(ethylene terephthalate) film, while the nonexposed MWCNT ink was removed by simple solvent washing. Via this technique, it was possible to direct-write MWCNTs on a flexible substrate, thus demonstrating the potential of polyimines for the fabrication of electronic inks

Ephemeral Amphiphilic Polyamines that Evaporate When TriggeredImplications for the Fabrication of Electronic Inks

Without surfactants, nanomaterials tend to be aggregated in the liquid state. However, the presence of surfactants in the solid state can negatively impact the mechanical, electronic, and optical properties of the nanomaterial. Here, we have explored the design of an ephemeral surfactant, that is to say a surfactant, which is stable in solution but can be depolymerized in the solid phase and then be evaporated. The reaction of glyoxal with a 1,3-diamine leads to an unprecedented ladder polyamine (LPA), which depolymerizes into evaporable monomers as soon as it is in contact with acid. These LPA oligomers were found to be amphiphilic and could be used to stabilize a dispersion of polymer nanoparticles (NPs) in water. Once dipped in a slightly acidic solution, the dried polymer film was found to be devoid of the LPA surfactant. This concept was used to fabricate an electronic ink based on multiwalled carbon nanotubes (MWCNTs) whereby the LPA depolymerization was triggered by a photoacid generator. After applying the ink on a glass substrate, the conductivity of the MWCNT films was low, due to the charge transfer resistance created by the interfacial surfactant. Once exposed to light, the surfactant depolymerized and evaporated, and the film recovered its native conductivity. We envision that these ephemeral surfactants could become useful assets in the fabrication of electronic inks

Mechanistic Insights on the Anionic Polymerization of Aliphatic Aldehydes

Self-immolative polymers are a class of stimuli-responsive macromolecules that can unzip down to monomer level. Among those, aliphatic polyaldehydes are particularly attractive due to their ability to rapidly depolymerize at ambient temperatures. By virtue of their thermal fragility, their preparation is challenging, and no mechanistic details exist about their synthesis. This study aims at clarifying the mechanism of the anionic polymerization of aliphatic aldehydes. For this purpose, several aliphatic aldehydes were polymerized using a variety of initiators. It was found that irrespective of the nature of the initiating species, the enolate formed between the initiator and the monomer is actually triggering the polymerization. The formation of an enolate is also responsible for a chain-transfer reaction to monomer, which limits the molecular weight of the polymer (ktr/kp = 0.0036). The microstructure of the polymer was determined by solid-state 13C nuclear magnetic resonance spectroscopy. It was found that all anionic polymers are linear, mostly isotactic (mm > 60%), and crystalline. These polymers are prone to depolymerize at room temperature in solution, making them interesting candidates as self-immolative polymers

18-Electron Ruthenium Phosphine Sulfonate Catalysts for Olefin Metathesis

The first instances of ruthenium alkylidene complexes based on chelating phosphine sulfonates are presented. Although these complexes are formally 18-electron complexes bearing <i>cis</i> phosphines and <i>cis</i> one-electron donors (sulfonates and chlorides), they are surprisingly active for ring-closing metathesis, cross-metathesis, and ring-opening metathesis polymerization, thus highlighting the unique potential of the sulfonate ligand in the design of a ruthenium metathesis catalyst

18-Electron Ruthenium Phosphine Sulfonate Catalysts for Olefin Metathesis

The first instances of ruthenium alkylidene complexes based on chelating phosphine sulfonates are presented. Although these complexes are formally 18-electron complexes bearing <i>cis</i> phosphines and <i>cis</i> one-electron donors (sulfonates and chlorides), they are surprisingly active for ring-closing metathesis, cross-metathesis, and ring-opening metathesis polymerization, thus highlighting the unique potential of the sulfonate ligand in the design of a ruthenium metathesis catalyst

Linear Polyethylene with Tunable Surface Properties by Catalytic Copolymerization of Ethylene with <i>N</i>-Vinyl-2-pyrrolidinone and <i>N</i>-Isopropylacrylamide

Linear Polyethylene with Tunable Surface Properties by Catalytic Copolymerization of Ethylene with N-Vinyl-2-pyrrolidinone and N-Isopropylacrylamid

Preparation of Functional Polyethylenes by Catalytic Copolymerization

Preparation of Functional Polyethylenes by Catalytic Copolymerizatio

Thermodynamic Control in the Catalytic Insertion Polymerization of Norbornenes as Rationale for the Lack of Reactivity of Endo-Substituted Norbornenes

The catalytic insertion polymerization of substituted norbornenes (NBEs) leads to the formation of a family of polymers which combine extreme thermomechanical properties as well as unique optical and electronic properties. However, this reaction is marred by the lack of reactivity of endo substituted monomers. It has long been assumed that these monomers chelate the metallic catalyst, leading to species which are inactive in polymerization. Here we examine the polymerization of cis-5-norbornene-2,3-dicarboxylic anhydride (so-called carbic anhydride, CA) with a naked cationic Pd catalyst. Although exo-CA can be polymerized, the polymerization of endo-CA stops after a single insertion. Surprisingly, no chelate is formed between the catalyst and endo-CA. Using DFT calculation, it is shown that while the insertion of exo-NBEs is exergonic, the insertion of two endo-CA in a row is endergonic. In this latter case, the enthalpy gain corresponding to the insertion of a double bond is not sufficient to overcome the entropic penalty associated with ligand binding. Thus, the different reactivity between endo and exo NBEs is thermodynamic in nature, and it is not controlled by kinetic factors. Interestingly, thermodynamics is also the main factor controlling the stereochemistry of the chain. For CA polymerization, and even for unsubstituted NBE polymerization, the formation of r and m dyads is, respectively, exergonic and endergonic, resulting in a polymer which is essentially disyndiotactic. Thus, this study demonstrates that thermodynamics can control the chemo- and stereoselectivity of a catalytic polymerization

Thermodynamic Control in the Catalytic Insertion Polymerization of Norbornenes as Rationale for the Lack of Reactivity of Endo-Substituted Norbornenes

The catalytic insertion polymerization of substituted norbornenes (NBEs) leads to the formation of a family of polymers which combine extreme thermomechanical properties as well as unique optical and electronic properties. However, this reaction is marred by the lack of reactivity of endo substituted monomers. It has long been assumed that these monomers chelate the metallic catalyst, leading to species which are inactive in polymerization. Here we examine the polymerization of <i>cis</i>-5-norbornene-2,3-dicarboxylic anhydride (so-called carbic anhydride, CA) with a naked cationic Pd catalyst. Although <i>exo</i>-CA can be polymerized, the polymerization of <i>endo</i>-CA stops after a single insertion. Surprisingly, no chelate is formed between the catalyst and <i>endo</i>-CA. Using DFT calculation, it is shown that while the insertion of <i>exo</i>-NBEs is exergonic, the insertion of two <i>endo</i>-CA in a row is endergonic. In this latter case, the enthalpy gain corresponding to the insertion of a double bond is not sufficient to overcome the entropic penalty associated with ligand binding. Thus, the different reactivity between endo and exo NBEs is thermodynamic in nature, and it is not controlled by kinetic factors. Interestingly, thermodynamics is also the main factor controlling the stereochemistry of the chain. For CA polymerization, and even for unsubstituted NBE polymerization, the formation of <i>r</i> and <i>m</i> dyads is, respectively, exergonic and endergonic, resulting in a polymer which is essentially disyndiotactic. Thus, this study demonstrates that thermodynamics can control the chemo- and stereoselectivity of a catalytic polymerization

Probing the Regiochemistry of Acrylate Catalytic Insertion Polymerization via Cyclocopolymerization of Allyl Acrylate and Ethylene

When palladium phosphine sulfonate catalysts were used, ethylene and allyl acrylate were copolymerized. The copolymer structure was analyzed by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) and was found to contain both δ-valerolactone and γ-butyrolactones inserted within the chain. These cyclic structures were determined to be the outcome of 1,2 allyl insertions and 2,1 acrylate insertions except when the acrylate was cyclopolymerized: in this case, regiochemistry of the insertion was 1,2. This first example of cyclopolymerization with Pd phosphine sulfonate catalysts outlines the extraordinary versatility of this family of compounds and paves the way to new polyolefins containing complex repeat units built in