1,3,4,5-Tetrasubstituted Poly(1,2,3-triazolium) Obtained through Metal-Free AA+BB Polyaddition of a Diazide and an Activated Internal Dialkyne.

A tetra(ethylene glycol)-based 1,3,4,5-tetrasubstituted poly(1,2,3-triazolium) is synthesized in two steps including: i) the catalyst-free polyaddition of a diazide and an activated internal dialkyne and ii) the N-alkylation of the resulting 1,2,3-triazole groups. In order to provide detailed structure/properties correlations different analogs are also synthesized. First, parent poly(1,2,3-triazole)s are obtained via AA+BB polyaddition using copper(I)-catalyzed alkyne-azide cycloaddition or metal-free thermal alkyne-azide cycloaddition (TAAC). Poly(1,2,3-triazole)s with higher molar masses are obtained in higher yields by TAAC polyaddition. A 1,3,4-trisubstituted poly(1,2,3-triazolium) structural analog obtained by TAAC polyaddition using a terminal activated dialkyne and subsequent N-alkylation of the 1,2,3-triazole groups enables discussing the influence of the methyl group in the C-4 or C-5 position on thermal and ion conducting properties. Obtained polymers are characterized by 1H, 13C, and 19F NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, size exclusion chromatography, and broadband dielectric spectroscopy. The targeted 1,3,4,5-tetrasubstituted poly(1,2,3-triazolium) exhibits a glass transition temperature of -23 °C and a direct current ionic conductivity of 2.0 × 10-6 S cm-1 at 30 °C under anhydrous conditions. The developed strategy offers opportunities to further tune the electron delocalization of the 1,2,3-triazolium cation and the properties of poly(1,2,3-triazolium)s using this additional substituent as structural handle.

Interface Manipulations Using Cross-Linked Underlayers and Surface-Active Diblock Copolymers to Extend Morphological Diversity in High-χ Diblock Copolymer Thin Films.

Top and bottom interfaces of high-χ cylinder-forming polystyrene-block-maltoheptaose (PS-b-MH) diblock copolymer (BCP) thin films are manipulated using cross-linked copolymer underlayers and a fluorinated phase-preferential surface-active polymer (SAP) additive to direct the self-assembly (both morphology and orientation) of BCP microdomains into sub-10 nm patterns. A series of four photo-cross-linkable statistical copolymers with various contents of styrene, a 4-vinylbenzyl azide cross-linker, and a carbohydrate-based acrylamide are processed into 15 nm-thick cross-linked passivation layers on silicon substrates. A partially fluorinated analogue of the PS-b-MH phase-preferential SAP additive is designed to tune the surface energy of the top interface. The self-assembly of PS-b-MH thin films on top of different cross-linked underlayers and including 0-20 wt % of SAP additive is investigated by atomic force microscopy and synchrotron grazing incidence small-angle X-ray scattering analysis. The precise manipulation of the interfaces of ca. 30 nm thick PS-b-MH films not only allows the control of the in-plane/out-of-plane orientation of hexagonally packed (HEX) cylinders but also promotes epitaxial order-order transitions from HEX cylinders to either face-centered orthorhombic or body-centered cubic spheres without modifying the volume fraction of both blocks. This general approach paves the way for the controlled self-assembly of other high-χ BCP systems.

Cross-linked polymer microparticles with tunable surface properties by the combination of suspension free radical copolymerization and Click chemistry.

We propose a general, versatile and broad in scope two-steps approach for the elaboration of cross-linked polymer microparticles (µPs) with tunable functionalities and surface properties. Surface-functionalized cross-linked polymer µPs with diameter in the 80 µm range are prepared by the combination of: 1) suspension free radical copolymerization of styrene, propargyl methacrylate and 1,6-hexanediol dimethacrylate, 2) subsequent covalent tethering of a variety of azide-functionalized moieties (i.e. rhodamine B fluorescent dye or poly(ethylene glycol) (PEG) brush precursor) by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and, 3) optional N-alkylation of the 1,2,3-triazole groups followed by anion exchange reaction to afford covalently-tethered 1,2,3-triazolium ionic liquids with iodide or cresol red counter-anions. The resulting µPs are characterized by laser diffraction, differential scanning calorimetry, as well as by optical, confocal fluorescence, scanning electron and atomic force microscopies. Finally, the rheological properties of concentrated suspensions (volume fractions of 0.40 and 0.44) of the different synthesized µPs dispersed in a 1:1 (vol/vol) mixture of polyalkylene glycol and water are studied. The modification of µPs surface properties contributes not only to change the stability of the suspensions against flocculation, but also to significantly modify their rheological behavior at high shear stresses. This represents a clear experimental evidence of the importance of non-hydrodynamic contact forces in the rheology of non-Brownian suspensions (NBSs).

Viscoelasticity-Induced Onset of Slip at the Wall for Polymer Fluids.

The progressive onset of slip at the wall, which corresponds to a slip length increasing with the solicitation time before reaching a plateau, has been investigated for model viscoelastic polymer solutions, allowing one to vary the longest relaxation time while keeping constant solid-fluid interactions. A hydrodynamic model based on a Maxwell fluid and the classical Navier's hypothesis of a linear response for the friction stress at the interface fully accounts for the data. In the limit of the linear viscoelasticity of the fluid, we could postulate a Newtonian response for the interfacial friction coefficient, reflecting the local character of solid-liquid friction mechanisms. Deviations between the experiments and our model are observed when the fluid is far from its linear viscoelastic behavior.

Access to Thermodynamic and Viscoelastic Properties of Poly(ionic liquid)s Using High-Pressure Conductivity Measurements.

In this paper, we examine the transport properties of a 1,2,3-triazolium-based poly(ionic liquid) (PIL) at ambient and elevated pressure up to 475 MPa. We show that the isothermal and isobaric conductivity measurements analyzed in the 3D plane give a unique possibility to estimate the thermodynamic (isothermal compressibility and thermal expansion coefficient) properties for PILs having a charge transport fully controlled by viscosity. This result, providing a direct connection between thermodynamic and dynamic properties of PILs, is of significant importance for both material scientists and practical applications.

Reusable Enzymatic Fiber Mats for Neurotoxin Remediation in Water.

Highly effective and reusable organophosphorus hydrolase (OPH)-loaded fiber mats have been fabricated that are capable of degrading toxic organophosphates (OPs) over a broad range of relevant concentrations (from 8 to 8250 ppm). The inherent fragility of enzymes, a major impediment in their incorporation into technologically relevant materials, was overcome while retaining their high catalytic efficiency, selectivity, and sensitivity via a random heteropolymers (RHP) approach. Kinetic analysis guides the design of polycaprolactone matrix morphology from films to fibers, facilitating substrate diffusion in the material. The RHP-OPH fiber mats demonstrate excellent stability and reusability with minimal requirements for storage, retaining over 40% of their initial activity after repeated daily use for three months. Practically, present studies provide valuable guidance toward fabrication of enzyme-based functional materials.

Temperature-Controlled Slip of Polymer Melts on Ideal Substrates.

The temperature dependence of the hydrodynamic boundary condition between a polydimethylsiloxane melt and two different nonattractive surfaces made of either an octadecyltrichlorosilane self-assembled monolayer or a grafted layer of short polydimethylsiloxane chains has been characterized. We observe a slip length proportional to the fluid viscosity. The temperature dependence is deeply influenced by the surfaces. The viscous stress exerted by the polymer liquid on the surface is observed to follow exactly the same temperature dependences as the friction stress of a cross-linked elastomer sliding on the same surfaces. Far above the glass transition temperature, these observations are rationalized in the framework of a molecular model based on activation energies: increase or decrease of the slip length with increasing temperatures can be observed depending on how the activation energy of the bulk viscosity compares to that of the interfacial Navier's friction coefficient.

Sensing adsorption kinetics through slip velocity measurements of polymer melts.

The evolution over time of the nonlinear slip behavior of a polydimethylsiloxane (PDMS) polymer melt on a weakly adsorbing surface made of short non-entangled PDMS chains densely end-grafted to the surface of a fused silica prism has been measured. The critical shear rate at which the melt enters the nonlinear slip regime has been shown to increase with time. The adsorption kinetics of the melt on the same surface has been determined independently using ellipsometry. We show that the evolution of slip can be explained by the slow adsorption of melt chains using the Brochard-de Gennes's model.

Random heteropolymers preserve protein function in foreign environments.

The successful incorporation of active proteins into synthetic polymers could lead to a new class of materials with functions found only in living systems. However, proteins rarely function under the conditions suitable for polymer processing. On the basis of an analysis of trends in protein sequences and characteristic chemical patterns on protein surfaces, we designed four-monomer random heteropolymers to mimic intrinsically disordered proteins for protein solubilization and stabilization in non-native environments. The heteropolymers, with optimized composition and statistical monomer distribution, enable cell-free synthesis of membrane proteins with proper protein folding for transport and enzyme-containing plastics for toxin bioremediation. Controlling the statistical monomer distribution in a heteropolymer, rather than the specific monomer sequence, affords a new strategy to interface with biological systems for protein-based biomaterials.

Friction of Polymers: from PDMS Melts to PDMS Elastomers.

The slip behavior of polydimethylsiloxane (PDMS) polymer melts flowing on weakly adsorbing surfaces made of short nonentangled PDMS chains densely end-grafted to silica has been characterized. For high enough shear rates, slip lengths proportional to the bulk fluid viscosity have been observed, in agreement with Navier's interfacial equation and demonstrating that the interfacial Navier's friction coefficient is a local quantity, independent of the polymer molecular weight. Comparing the interfacial shear stresses deduced from these measured slip lengths to available friction stress measured for cross-linked PDMS elastomers, we further demonstrate the local character of the friction coefficient and compare its value to the monomer-monomer friction.

Influence of grafting on the glass transition temperature of PS thin films.

We present an investigation of the effect of the interaction between a thin polystyrene film and its supporting substrate on its glass transition temperature ([Formula: see text]). We modulate this interaction by depositing the film on end-tethered polystyrene grafted layers of controlled molecular parameters. By comparing [Formula: see text] measurements versus film thickness for films deposited on different grafted layers and films deposited directly on a silicon substrate, we can conclude that there is no important effect of the film-subtrate interaction. Our interpretation of these results is that local orientation and dynamic effects substantial enough to influence [Formula: see text] cannot readily be obtained by grafting prepolymerized chains to a surface, due to intrinsic limitation of the surface grafting density.

Fluorinated Poly(ionic liquid) Diblock Copolymers Obtained by Cobalt-Mediated Radical Polymerization-Induced Self-Assembly.

Poly(ionic liquid)s (PILs) have attracted considerable attention as innovative single-ion solid polyelectrolytes (SPEs) in substitution to the more conventional electrolytes for a variety of electrochemical devices. Herein, we report the precise synthesis, characterization, and use as single-ion SPEs of a novel double PIL-based amphiphilic diblock copolymer (BCP), i.e., where all monomer units are of N-vinyl-imidazolium type, with triethylene glycol pendant groups in the first block and a statistical distribution of N-vinyl-3-ethyl- and N-vinyl-3-perfluorooctyl-imidazolium bromides in the second block. BCP synthesis is achieved directly in water by a one-pot process, by cobalt-mediated radical polymerization-induced self-assembly (CMR-PISA). A subsequent anion exchange reaction substituting bis(trifluoromethylsulfonyl)imide (Tf2N-) for bromide (Br-) counter-anions leads to PIL BCPs with two different lengths of the first block. They demonstrate ionic conductivity σDC = 1-3 × 10-7 S cm-1, as determined by broadband dielectric spectroscopy at 30 °C (under anhydrous conditions), and exhibit wide electrochemical stability (up to 4.8 V versus Li+/Li) and form free-standing films with mechanical properties suited for SPE applications (Young's modulus = 3.8 MPa, elongation at break of 250%) as determined by stress/strain experiments.

1,2,3-Triazolium-Based Epoxy-Amine Networks: Ion-Conducting Polymer Electrolytes.

A diepoxy-functionalized 1,2,3-triazolium ionic liquid is synthesized in three steps and used in combination with a poly(propylene glycol) diamine to obtain ion-conducting epoxy-amine networks (EANs). The curing kinetics are followed by Fourier transform infrared spectroscopy, while the physical, mechanical, and ion-conducting properties of the resulting networks are studied by swelling experiments, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical thermal analysis, and broadband dielectric spectroscopy. The curing kinetics and thermomechanical properties of this system are relatively similar to those of conventional DGEBA- (bisphenol A diglycidyl ether)-based EANs with low glass transition temperature (Tg = -44 and -52 °C, respectively) characteristic of rubbery polymer networks. The anhydrous ionic conductivity of the pure network at 30 °C reaches a remarkably high value of 2 × 10(-7) S cm(-1) that could be further increased to 10(-6) S cm(-1) by the addition of 10 wt% LiTFSI.

Poly(1,2,3-triazolium)s: a new class of functional polymer electrolytes.

Poly(ionic liquid)s (PILs) are a unique class of polyelectrolytes having properties suited for modern technological applications such as electrochemical devices (batteries, supercapacitors, light-emitting electrochemical cells), ion-gated field effect transistors, electrochromic devices, fuel cells, dye sensitized solar cells, catalysis, or soft robotics. Their structure and properties can be finely tuned by unlimited combinations issued from extended pools of cationic and anionic building blocks. In a constant quest for the development of solid polymer electrolytes with enhanced physical, mechanical and (electro)chemical properties, a new class of PILs based on 1,2,3-triazolium cations has been recently developed. Their preparation takes advantage of the beneficial features of the multiple combinations between the Click chemistry philosophy with macromolecular engineering techniques to afford tunable and highly functional ion conducting materials thus stretching out the actual boundaries of PILs macromolecular design. This feature article summarizes the different strategies developed so far for the synthesis of 1,2,3-triazolium-based PILs (TPILs) since their first introduction in 2013.

Enhanced Ionic Conductivity of a 1,2,3-Triazolium-Based Poly(siloxane ionic liquid) Homopolymer.

A 1,2,3-triazolium-based poly(siloxane ionic liquid) (PSIL) is synthesized by UV-triggered thiol-ene ligation between a poly[(mercaptopropyl)methylsiloxane] and a tailor-made vinyl-functionalized triethylene glycol-based 1,2,3-triazolium ionic liquid. The quantitative nature of the thiol-ene coupling is demonstrated by 1H and 13C NMR, whereas properties of this new PSIL are discussed based on solubility, size exclusion chromatography, differential scanning calorimetry, thermogravimetric analysis, and broadband dielectric spectroscopy measurements. Besides exhibiting low glass transition temperature (Tg = -62 °C) and high thermal stability (Td10 = 284 °C), this new class of poly(1,2,3-triazolium) demonstrates the highest value of bulk anhydrous ionic conductivity reported to date for PILs (σDC = 7 × 10-5 S cm-1 at 30 °C).

Highly ordered nanoporous films from supramolecular diblock copolymers with hydrogen-bonding junctions.

We designed efficient precursors that combine complementary associative groups with exceptional binding affinities and thiocarbonylthio moieties enabling precise RAFT polymerization. Well defined PS and PMMA supramolecular polymers with molecular weights up to 30 kg mol(-1) are synthesized and shown to form highly stable supramolecular diblock copolymers (BCPs) when mixed, in non-polar solvents or in the bulk. Hierarchical self-assembly of such supramolecular BCPs by thermal annealing affords morphologies with excellent lateral order, comparable to features expected from covalent diblock copolymer analogues. Simple washing of the resulting materials with protic solvents disrupts the supramolecular association and selectively dissolves one polymer, affording a straightforward process for preparing well-ordered nanoporous materials without resorting to crosslinking or invasive chemical degradations.

Reprocessing and Recycling of Highly Cross-Linked Ion-Conducting Networks through Transalkylation Exchanges of C-N Bonds.

Exploiting exchangeable covalent bonds as dynamic cross-links recently afforded a new class of polymer materials coined as vitrimers. These permanent networks are insoluble and infusible, but the network topology can be reshuffled at high temperatures, thus enabling glasslike plastic deformation and reprocessing without depolymerization. We disclose herein the development of functional and high-value ion-conducting vitrimers that take inspiration from poly(ionic liquid)s. Tunable networks with high ionic content are obtained by the solvent- and catalyst-free polyaddition of an α-azide-ω-alkyne monomer and simultaneous alkylation of the resulting poly(1,2,3-triazole)s with a series of difunctional cross-linking agents. Temperature-induced transalkylation exchanges of C-N bonds between 1,2,3-triazolium cross-links and halide-functionalized dangling chains enable recycling and reprocessing of these highly cross-linked permanent networks. They can also be recycled by depolymerization with specific solvents able to displace the transalkylation equilibrium, and they display a great potential for applications that require solid electrolytes with excellent mechanical performances and facile processing such as supercapacitors, batteries, fuel cells, and separation membranes.

Accelerated solvent- and catalyst-free synthesis of 1,2,3-triazolium-based poly(ionic liquid)s.

A straightforward and expeditious monotopic approach for the preparation of 1,2,3-triazolium-based poly(ionic liquids) (TPILs) is reported. It is based on the solvent- and catalyst-free polyaddition of an α-azide-ω-alkyne monomer in the presence of methyl iodide or N-methyl bis[(trifluoromethyl)sulfonyl]imide alkylating agents. Poly(1,2,3-triazole)s generated in bulk or by thermal azide-alkyne cycloaddition (AAC) are quaternized in-situ to afford TPILs composed of 1,3,4- and 1,3,5-trisubstituted 1,2,3-triazolium units. The physical and ion-conducting properties of the prepared samples are compared with the TPILs composed solely of 1,3,4-trisubstituted 1,2,3-triazolium units obtained through a multistep approach involving copper(I)-catalyzed AAC polyaddition, quaternization of the 1,2,3-triazole groups, and anion metathesis. TPILs obtained through the monotopic approach display thermal stabilities and ionic conductivities comparable to their pure regioisomeric analogues.

Enhancing Properties of Anionic Poly(ionic liquid)s with 1,2,3-Triazolium Counter Cations.

A series of anionic poly(ionic liquid)s with 1,2,3-triazolium counter cations are prepared by cation exchange between tailormade 1,3,4-trialkylated-1,2,3-triazolium iodides and a polystyrene derivative having pendant potassium bis(trifluoromethylsulfonyl)imide groups. The physical and ion-conducting properties of the resulting materials are compared to the parent potassium-containing polyelectrolyte based on 1H NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and broadband dielectric spectroscopy (BDS) measurements. Substitution of the potassium counter cation by 1,2,3-triazolium charge carriers affords polyelectrolytes with improved processability (broader solubility and removal of the crystalline behavior) as well as a substantial increase in anhydrous ionic conductivity.

UV-Patterning of Ion Conducting Negative Tone Photoresists Using Azide-Functionalized Poly(Ionic Liquid)s.

The patterning of solid electrolytes that builds upon traditional fabrication of semiconductors is described. An azide-functionalized poly(1,2,3-triazolium ionic liquid) is used as an ion conducting negative tone photoresist. After UV-irradiation through an optical mask, micron-scaled, patterned, solid polyelectrolyte layers with controlled sizes and shapes are obtained. Furthermore, alkylation of poly(1,2,3-triazole)s can be generalized to the synthesis of poly(ionic liquid)s with a tunable amount of pendant functionalities.