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Polyurethane (PU) adhesives and coatings are widely used to fabricate high-quality materials due to their excellent properties and their versatile nature, which stems from the wide range of commercially available polyisocyanate and polyol precursors. This polymer family has traditionally been used in a wide range of adhesive applications including the bonding of footwear soles, bonding of wood (flooring) to concrete (subflooring), in the automotive industry for adhering different car parts, and in rotor blades, in which large surfaces are required to be adhered. Moreover, PUs are also frequently applied as coatings/paints for automotive finishes and can be applied over a wide range of substrates such as wood, metal, plastic, and textiles. One of the major drawbacks of this polymer family lies in the use of toxic isocyanate-based starting materials. In the context of the REACH regulation, which places restrictions on the use of substances containing free isocyanates, it is now urgent to find greener routes to PUs. While non-isocyanate polyurethanes (NIPUs) based on the polyaddition of poly(cyclic carbonate)s to polyamines have emerged in the past decade as greener alternatives to conventional PUs, their industrial implementation is at an early stage of development. In this review article, recent advances in the application of NIPUs in the field of adhesives and coatings are summarized. The article also draws attention to the opportunities and challenges of implementing NIPUs at the industrial scale.

Solid-state lithium batteries are considered one of the most promising battery systems due to their high volumetric energy density and safety. Poly(ethylene oxide) (PEO) is the most commonly used solid polymer electrolyte in solid-state batteries. In this article, we introduce new polyphosphoester polymer electrolytes, which show improved flame retardant properties in comparison with PEO. For this purpose, new polyphosphoester copolymers were synthesized, including phosphoester, poly(ethylene glycol) (PEG) and UV cross-linkable vinyl units. Solid polymer electrolyte films based on polyphosphoester copolymers and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were prepared by curing under UV-light. The crystallinity present in the copolymers due to the PEG segment decreases with the amount of salt in the electrolyte, as seen by DSC. Solid polymer electrolytes based on polyphosphoester copolymers show ionic conductivity values as high as 2 × 10−4 S cm−1 at 70 °C. FTIR analysis showed that lithium cations complexed with phosphoester groups provoked an increase in the lithium transference number to 0.26 as compared to that of PEO 0.17. Pyrolysis flow combustion calorimetry (PCFC) or micro-calorimetry results demonstrated the improved flame retardancy of the polyphosphoesters in comparison to a reference PEO based polymer electrolyte. The selected polyphosphoester solid electrolyte was investigated in a solid-state lithium cell Li0/polymer electrolyte/LFP battery showing a specific capacity retention close to 80% and coulombic efficiency greater than 98% over 100 cycles at 70 °C.

The synthesis and properties of hybrid poly(ε-caprolactone) (PCL)–poly(ethylene oxide) (PEO) covalent adaptable networks have been investigated.

New biomimetic micro- and nano-CsU-based fibrous scaffolds electrospun from solution containing high purity-medical grade chitosan (CsU) of fungus origin (CsU1, Mv ~174,000 and CsU2, 205,000, degree of deacetylation (DDA) ~65%) and polyethylene oxide (PEO, Mv ~ 900,000), in the presence of given amounts of Triton X-100 (from 0.01 to 0.5 wt%) as surfactant were fabricated. We demonstrate that by carefully selecting compositions and surfactant levels, porous mats with CsU content up to 90% (at this molecular weight and DDA) were achieved. Remarkable long-term stability in water or phosphate buffer solution storage were obtained by developing post-electrospinning treatment allowing the complete elimination of the PEO from the CsU-fibers as demonstrated by TGA, DSC and ESEM analysis. Subsequent reacetylation procedure was applied to convert 2D biomimetic chitosan mats to chitin (CsE)-based ones while preserving the nanofiber structure. This innovative procedure allows tuning and modifying the thermal, mechanical properties and more importantly the biodegradation abilities (fast enzymatic biodegradation in some cases and slower on the others) of the prepared nanofibrous mats. The established reproducible method offers the unique advantage to modulate the membrane properties leading to stable 2D biomimetic CsU and/or chitin (CsE) scaffolds tailor-made for specific purposes in the field of tissue engineering.

Polyurethane (PU) foams are indisputably daily essential materials found in many applications, notably for comfort (for example, matrasses) or energy saving (for example, thermal insulation). Today, greener routes for their production are intensively searched for to avoid the use of toxic isocyanates. An easily scalable process for the simple construction of self-blown isocyanate-free PU foams by exploiting the organocatalyzed chemo- and regioselective additions of amines and thiols to easily accessible cyclic carbonates is described. These reactions are first validated on model compounds and rationalized by DFT calculations. Various foams are then prepared and characterized in terms of morphology and mechanical properties, and the scope of the process is illustrated by modulating the composition of the reactive formulation. With impressive diversity and accessibility of the main components of the formulations, this new robust and solvent-free process could open avenues for construction of more sustainable PU foams, and offers the first realistic alternative to the traditional isocyanate route.

Charged nanofibers were prepared by electrospinning (ESP) poly(e-caprolactone) with a copolymer bearing carboxylic acid functions. The presence of these functions allowed exposing some negative charges on the fiber surface, by dipping the fibers in a phosphate buffer. A layer of chitosan, a polycation in acidic medium, was then deposited on the nanofiber surface, thanks to electrostatic attraction. Fibers were characterized at each step of the process and the influence of the copolymer architecture on chitosan deposition was discussed. The antibacterial activity of the resulting fibers was finally assessed.

Here we report that grafting temperature-responsive polymers onto hyaluronic acid allows temperature-induced self-assembly into nanogels with tunable size. These nanogels can be easily loaded with hydrophobic molecules and hold potential for anti-cancer drug delivery towards human ovarian cancer cells.

International audience; In the past few decades, various nanovehicles have been developed as drug delivery systems, in which inorganic and organic components are integrated within a nano-object. Upon the application of remote stimuli, e.g. alternating magnetic field, near infrared or ultrasound radiations, the release of guest molecules can be triggered in a quite controlled manner. Herein, we review different hybrid nanostructures which have already been reported for the remotely triggered release, such as those based on (1) host–guest conjugates, (2) core–corona nanoparticles, (3) polymer nanogels, (4) polymer micelles, (5) liposomes, (6) mesoporous silica particles and (7) hollow nanoparticles. Moreover, we also summarize six underlying mechanisms that govern such a kind of remotely triggered release behaviours: (1) enhanced diffusion and/or permeation, (2) thermo- or photo-labile bond cleavage, (3) fusion of phase-changed materials, (4) photo-induced isomerisation, (5) thermo-induced swelling/de-swelling of thermo-responsive polymers, and (6) destruction of the nanostructures. The ways in which different components are incorporated into an integrated hybrid nanostructure and how they contribute to the remotely triggered release behaviours are detailed.

Green routes for the synthesis of high-performance isocyanate-free polyurethane coatings and adhesives are intensively searched for. In this article, we report a solvent- and isocyanate-free formul...

In this work, the redispersion of three nanocrystalline TiO2 colloids is studied: one pure and two Fe-doped titania. These three colloids are produced by an easy aqueous sol–gel synthesis using precipitation-acidic peptization of Ti precursor. For the two Fe-doped TiO2, one is doped during synthesis (primary doping) and the other is doped after the synthesis (secondary doping). The initial colloids are composed of crystalline TiO2 particles around 7 nm with good photocatalytic properties, tested on PNP degradation under visible light (wavelength >390 nm). The powders obtained by air drying of these three colloids are redispersed in water to produce colloids, which are compared to the initial colloid produced. For each colloid, five cycles of drying redispersion are achieved. The colloids are characterized by dynamic light scattering, zeta potential measurements, inductively coupled plasma–atomic emission spectroscopy, X-ray diffraction, nitrogen adsorption–desorption measurements, Mossbauer spectroscopy, diffuse reflectance spectroscopy, and photocatalytic tests. The results show that similar products are obtained between the cycles, maintaining homologous properties of colloids. This property of redispersion is mainly due to the acid (HNO3, HCl, or H2SO4) which protonates the surface of the TiO2 nanoparticle leading to high-surface charges and electrostatic repulsions between aggregates. This property can be very useful for industrial applications of this synthesis, especially as it allows the volume and weight to be reduced for transportation and storage. Moreover, results show that the pure TiO2 powder can be doped during its redispersion step. The redispersion of the TiO2 developed here is possible without surface functionalization or multiple step processes, contrary to commercial Degussa P25. A 2-year stability study of all the produced colloids has been performed by following the evolution of the macroscopic aspect and the physicochemical properties of these sols. This study showed high stability of the produced colloids.

Ion Mobility (IM) coupled to Mass Spectrometry (MS) has been used for several decades, bringing a fast separation dimension to the MS detection. IM-MS is a convenient tool for structural elucidation. The folding of macromolecules is often assessed with the support of computational chemistry. However, this strategy is strongly dependent on computational initial guesses. Here, we propose the analysis of the Collision Cross-Section (CCS) trends of synthetic homopolymers based on a fitting method which does not rely on computational chemistry a prioris of the three-dimensional structures. The CCS trends were evaluated as a function of the polymer chain length and the charge state. This method is also applicable to mobility trends. It leads to two parameters containing all information available through IM(-MS) measurements. One parameter can be interpreted as an apparent density. The second parameter is related to the shape of the ions and leads us to introduce the concept of trends with constant apparent density. Based on the two fitting parameters, a method for IM trend predictions is elaborated. Experimental deviations from the predictions facilitate detecting structural rearrangements and three-dimensional structure differences of the cationized polymer ions. This leads for instance to an easy identification and prediction of the presence of different polymer topologies in complex polymer mixtures. The classification of predicted trends could as well allow for software-assisted data processing. Finally, we suggest the link between the CCS trends of homopolymers and those obtained from (monodisperse) biomolecules to interpret potential folding differences during IM-MS studies.

This work investigates in detail the Joule resistive heating phenomenon of electroactive shape memory composites (SMC) when an electric current is injected at constant power. The SMC is a covalent poly(ϵ-caprolactone) network filled with 3 wt% of multiwall carbon nanotubes. The resistive heating of the SMC is studied by means of surface temperature measurements, analytical formulas and a coupled 3D thermo-electric numerical model. Analytical expressions are derived for the 2D temperature distribution within a parallelepipedic SMC, either with constant or linearly-dependent electrical resistivity. These analytical expressions can be used to investigate the influence of geometrical and material parameters in the steady-state temperature and its distribution across the sample. The results also allow one to identify the parameters that are crucial for predicting the temperature rise due to resistive heating: the temperature dependence of the resistivity has little effect on the steady-state temperature, whereas the thermal conductivity plays a significant role. The time-dependent temperature is shown to be related to the particular temperature dependence of heat capacity. Furthermore, the presence of external objects (clamps or grips) used during the shape memory cycle must be taken into consideration for a certain temperature to be reached since they result in a lower steady-state temperature and a slower resistive heating phenomenon. With the findings presented in this work, accurate resistive heating can be predicted for a SMC upon the injection of an electric current at constant power.

Hierarchical porous N-doped carbon (NPC) is prepared by pyrolysis of poly(methyl methacrylate) (PMMA) particles decorated by graphene oxide (GO) and polypyrrole (PPy) as precursors and used as anode for lithium-ion batteries. The composite precursors with different diameter and composition (PMMA/GO/PPy-A and B) were conveniently prepared by dispersion polymerization of methyl methacrylate in the presence of graphene oxide as stabilizer in aqueous medium, followed by addition of pyrrole and its oxidative polymerization. After pyrolysis, the resulting NPC composites with hierarchically structured macro- and mesopores exhibit high surface area (289–398 m2/g) and different N-doping levels (7.46 and 4.22 wt% of nitrogen content). The NPC with the highest N-doping level (7.46 wt%) shows high reversible capacities of 831 mAh/g at 74.4 mA/g (C/5) after 50 cycles and excellent rate performances.

Structuring poly(ionic liquid)s (PILs) into porous materials or swelling PILs with free ionic liquids (ILs) has received specific attention recently and contributed to the improvement of the performances of these materials used in a wide range of applications. The present work aims to take advantage of both approaches and produce macroporous PIL/IL gels in a single step through an innovative emulsion-templated polymerization method based on supercritical carbon dioxide (scCO2). More precisely, IL vinyl monomers and crosslinkers were polymerized in the presence of non-polymerizable ILs within the outer phase of a CO2-in-IL high internal phase emulsion (HIPE). Specific macromolecular surfactants were synthesized using controlled radical polymerization techniques and tested for the stabilization of the CO2-in-IL emulsions. While optimizing the polymerization conditions, we found that adding a limited amount of water in the medium was beneficial for the emulsion stability. Overall, this straightforward process provided access to macroporous polyHIPEs composed of poly(vinyl imidazolium) networks swollen by ‘free’ vinyl imidazolium-based ILs having interesting properties such as switchable polarity upon a simple anion exchange reaction.

Bio- and CO2-based high performance thermoset poly(hydroxyurethane) (PHU) glues were designed from solvent- and isocyanate-free formulations based on cyclocarbonated soybean oil, diamines (aliphatic, cycloaliphatic or aromatic) and functional silica or ZnO fillers. Shear strength values and cohesive or adhesive failure of glues were correlated with the crosslinking, mechanical and thermal properties of the nanocomposite PHU thermosets. The addition of SiO2 or ZnO fillers bearing cyclic carbonate groups at their surface enabled strong improvement in the adhesion performances of the glues up to 173% compared to the unfilled PHUs. The most performing reinforced PHU adhesives showed a shear strength up to 11.3 MPa for an aluminum substrate, and 10.1 MPa for stainless steel with cohesive failure. This study highlights that bio-based nanocomposite PHU thermosets are promising sustainable alternatives to conventional glues made of toxic formulations containing isocyanates.

Well-defined poly(lactide)-based block copolymers were synthesized by a heterogeneous solvent and metal-free green approach by using organocatalysts in supercritical carbon dioxide (scCO2). We first report on the homopolymerization of both l - and d , l -lactide by organocatalyzed Ring-Opening Polymerization (o-ROP) by using a bicomponent organocatalyst composed of a thiourea derivative and various tertiary amines as cocatalysts. Control over the molar mass and dispersity is achieved until high monomer conversion although the polylactides are insoluble in the polymerization medium. The precision synthesis of PLA-based block copolymers from various CO2-phobic hydroxyl end-capped macroinitiators such as polyethylene glycol, polycaprolactone, polybutylene succinate and polyphosphoester was then reported. Merging scCO2 with this organocatalytic system provides therefore a unique tool for the design under solvent-free conditions of poly(lactide)-based block copolymers that are insoluble in scCO2.

Access to well-defined polymers made of the so-called ‘Less Activated Monomers’ (LAMs) via controlled radical polymerization has long been a challenge due to the lack of radical stabilizing group on the double bond of these monomers. This Feature Article summarizes substantial progress in the organometallic-mediated radical polymerization (OMRP) of this important class of monomers including vinyl esters, olefins, vinyl chloride, vinyl amides, or ionic-liquid vinyl monomers. It aims to provide a clear and comprehensive account of the fundamentals and challenges in the OMRP of LAMs as well as an overview of the resulting macromolecular engineering opportunities. The input of photochemistry, environmentally friendly solvents or flow reactors in OMRP is also presented. Finally, it emphasizes how some well-defined LAMs-based materials contributed to the development of specific applications notably in the fields of biomedicine or energy.

This paper presents the work carried out within the European project RENAISSANCE-ITN, which was dedicated to the development of innovative polyelectrolytes for energy and environmental applications. Within the project different types of innovative polyelectrolytes were synthesized such as poly(ionic liquid)s coming from renewable or natural ions, thiazolium cations, catechol functionalities or from a new generation of cheap deep eutectic monomers. Further, macromolecular architectures such as new poly(ionic liquid) block copolymers and new (semi)conducting polymer/polyelectrolyte complexes were also developed. As the final goal, the application of these innovative polymers in energy and the environment was investigated. Important advances in energy storage technologies included the development of new carbonaceous materials, new lignin/conducting polymer biopolymer electrodes, new iongels and single-ion conducting polymer electrolytes for supercapacitors and batteries and new poly(ionic liquid) binders for batteries. On the other hand, the use of innovative polyelectrolytes in sustainable environmental technologies led to the development of new liquid and dry water, new materials for water cleaning technologies such as flocculants, oil absorbers, new recyclable organocatalyst platforms and new multifunctional polymer coatings with antifouling and antimicrobial properties. All in all this paper demonstrates the potential of poly(ionic liquid)s for high-value applications in energy and enviromental areas. © 2017 Society of Chemical Industry

Drug-eluting sutures represent the next generation of surgical sutures since they fulfill their mechanical functions but also deliver the drug in their vicinity after implantation. These implants are produced by a variety of manufacturing processes. Drug-eluting sutures represent the next generation of surgical sutures since they fulfill their mechanical functions but also deliver the drug in their vicinity after implantation. These implants are produced by a variety of manufacturing processes. Two general approaches can be followed: (i) the ones that add the API into the material during the manufacturing process of the suture and (ii) the ones that load the API to an already manufactured suture. Areas covered: This review provides an overview of the current manufacturing processes for drug-eluting suture production and discusses their benefits and drawbacks depending on the type of drugs. The mechanical properties and the drug delivery profile of drug-eluting sutures are highlighted since these implants must fulfill both criteria. Expert opinion: For limited drug contents, melt extrusion and electrospinning are the emerging processes since the drug is added during the suture manufacture process. Advantageously, the drug release profile can be tuned by controlling the processing parameters specific to each process and the composition of the drug-containing polymer. If high drug content is targeted, the coating or grafting of a drug layer on a pre-manufactured suture allows for preservation of the tensile strength requirements of the suture.

In the recent decades, biodegradable and biocompatible polyphosphoesters (PPEs) have gained wide attention in the biomedical field as relevant substitutes for conventional aliphatic polyesters. These amorphous materials of low glass transition temperature offer promise for the design of soft scaffolds for tissue engineering. Advantageously, the easy variation of the nature of the lateral pendant groups of PPEs allows the insertion of pendent unsaturations valuable for their further cross-linking. In addition, varying the length of the pendent alkyl chains allows tuning their hydrophilicity. The present work aims at synthesizing PPE networks of well-defined hydrophilicity and mechanical properties. More precisely, we aimed at preparing degradable materials exhibiting identical hydrophilicity but different mechanical properties and vice versa. For that purpose, PPE copolymers were synthesized by ring-opening copolymerization of cyclic phosphate monomers bearing different pendent groups (e.g., methyl, butenyl, and butyl). After UV irradiation, a stable and well-defined cross-linked material is obtained with the mechanical property of the corresponding polymer films controlled by the composition of the starting PPE copolymer. The results demonstrate that cross-linking density could be correlated with the mechanical properties, swelling behavior, and degradation rate of the polymers network. The polymers were compatible to human skin fibroblast cells and did not exhibit significant cytotoxicity up to 0.5 mg mL-1. In addition, degradation products appeared nontoxic to skin fibroblast cells and showed their potential as promising scaffolds for tissue engineering.

We report organic radical functionalized graphite nanoplatelet (GNP) via a simple click reaction of the polymer propagated radical, polyvinylimidazolium functionalized with redox-active free radical TEMPO pendants groups. The as-obtained monomer was successfully polymerized by free radical polymerization at low temperature (40 ° C) by using 2,2’ - azobis(4-methoxy-2.4-dimethyl valeronitrile) as initiator. Finally, the CNO bond of the alkoxyamine pendant groups was thermally cleaved releasing the redox-active TEMPO nitroxide radicals. This simple and efficient strategy to synthesize graphite-functionalized PILs will provide new opportunities to fabricate many other polymer composite electrodes for desired electrochemical performance.

Since the discovery of polyurethanes (PU) by Otto Bayer in 1937, PU hydrogels are still commonly produced by the polyaddition of nasty and toxic polyisocyanates with polyols in organic solvents or ...

Simultaneous condensation of aromatic aldehydes (ArxCHO; x = 1–4) on chitosan biopolymer (CS) affords, after water-evaporation, structurally-conjugated aryl-functionalized CS-Arx-f films. Similarly, cooperative assembly of two-dimensional nanometric graphene oxide (GO), aromatic aldehyde and chitosan provides transparent, flexible and crack-free aldehyde-functionalized, ternary-reinforced CS-Arx-GO-f nanocomposite films. Homogenous films were obtained using ortho-hydroxybenzaldehyde Ar1 while the para-hydroxybenzaldehyde Ar4 was prone to packing inside. Textural and mechanical properties were investigated and expectedly, significant improvement was found for CS-Ar1-GO-f because of the great dispersion of the aromatic and the presence of the filler. The sensitivity of unsaturated C N imine bond to hydrolysis was explored for triggering controlled release of aromatics from the as-prepared films. All of them were found to induce a time-dependent aromatic release. It has been moreover observed that the release was significantly delayed in CS-Arx-GO-f compared to CS-Arx-f, a fact attributed to the interplay of the ring with the basal and edges of graphene oxide, through π-π stacking and additional hydrogen bonding interactions. This finding shows that beyond the conventional wisdom using fillers for improving thermal and mechanical properties, the tiny carbon sheets can act as a regulator for aldehyde release, thereby providing a way for more controlled chemical delivery from confined nanocomposites.

In the last few years, polycarbonates have been identified as alternatives to poly(ethylene oxide) as polymer electrolytes for lithium battery applications. In this work, we show the design of CO2-sourced polycarbonates for their use in room temperature operating lithium batteries. Novel functional polycarbonates with alternating oxo-carbonate moieties and polyethylene oxide segments are synthesized by the facile room temperature (rt) organocatalyzed polyaddition of CO2-sourced bis(aalkylidene carbonate)s (bis-aCCs) with polyethylene oxide diols. The effect of the molar mass of olyethylene oxide on the ionic conductivity and thermal properties of poly(oxo-carbonate)s is investigated. The best candidate shows a low glass transition temperature of 44 C and a high ionic conductivity of 3.75 10 5 S cm 1 at rt when loaded with 30 wt% bis(trifluoromethanesulfonyl)imide salt (LiTFSI) without any solvent. An all-solid semi-interpenetrated network polymer electrolyte (SIN-SPE) is then fabricated by UV cross-linking of a mixture containing specifically designed poly(oxo-carbonate) bearing methacrylate pendants, diethylene glycol diacrylate and the previously described poly(oxocarbonate) containing LiTFSI. The resulting self-standing membrane exhibits a high oxidation stability up to 5 V (vs. Li/Li+), an ionic conductivity of 1.1 10 5 S cm 1 at rt (10 4 S cm 1 at 60 C) and promising mechanical properties. Assembled in a half cell configuration with LiFePO4 (LFP) as the cathode and lithium as the anode, the all-solid cell delivers a discharge capacity of 161 mA h g 1 at 0.1C and 60 C, which is very close to the theoretical capacity of LFP (170 mA h g 1). Also, a stable reversible cycling capacity over 400 cycles with a high coulombic efficiency of 99% is noted at 1C. Similar results are obtained at rt provided that 10 wt% tetraglyme as a plasticizer was added to the SIN-SPE. -Fonds National pour la Recherche Scientifique” (F.R.S.-FNRS) -Fonds Wetenschappelijk Onderzoek– Vlaanderen (FWO) -EOS project no. 019618F (ID EOS: 30902231). - CESAM Research Unit. - European Research Council by Starting Grant Innovative Polymers for Energy Storage (iPes) 306250 -Basque Government through ETORTEK Energigune 2013 and IT 999-16. - Spanish Ministry of Education, Culture and Sport for the predoctoral FPU fellowship received

The cobalt-mediated radical polymerization (CMRP) of new ionic liquid monomers (ILMs), vinyl imidazolium functionalized with redox-active free radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)VIm and its CMR copolymerization with vinyl imidazolium units functionalized with triethylene oxide (TEG)VIm produced a well-defined PILs (co)polymers. The controlled nature of (co)polymerization can be seen from the linear first-order kinetic plot, linear evolutions of the molar mass with total monomer conversion and the low polydispersity of the resulting (co)polymers. By combining the redox activity of (TEMPO)PVIm and remarkable ionic conductivity of (TEG)PVIm, outstanding rate capability performance was achieved with a remarkable capacity of 69 mAh g−1 at 60C. The obtained organic electrode can serve as sustainable electrodes in lithium ion batteries.

Polydimethylsiloxanes (PDMSs) bearing photoreactive coumarin groups have been synthesized by amidation of a coumarin acid chloride derivative with various amine-functionalized PDMSs. Upon exposure to UV light having a wavelength of above 300 nm, multifunctional coumarin-PDMSs are transformed into covalent networks via [2 + 2] photocycloaddition of two coumarin moieties forming a cyclobutane ring. Taking advantage of the possible localized irradiation through a photomask, a novel concept to generate patterned PDMS films with various surface topologies was demonstrated. This concept is based on the combination of a low molar mass difunctional PDMS with a multifunctional PDMS of a high molar mass forming a photoreversible network allowing osmotic diffusion of a linear PDMS-coumarin of low molecular weight in a loosely crosslinked network. Advantageously, illumination by a light source at 254 nm induces the photocleavage of the cyclobutane cross-links offering some photo-induced reversibility to the PDMS network. These novel photo-responsive networks are interesting for several applications, in photo-adaptable biomedical implants (particularly photo-adjustable intra-ocular lenses), photo-tuneable patterned microsystems (e.g. for microfluidics) and photo-switchable controlled release systems.

The aim of this study was to evaluate hot-melt extrusion (HME) as a continuous process to form cyclodextrin (CD) inclusion complexes in order to increase the solubility and dissolution rate of itraconazole (ITZ), a class II model drug molecule of the Biopharmaceutics Classification System. Different CD derivatives were tested in a 1:1 (CD:ITZ) molar ratio to obtain CD ternary inclusion complexes in the presence of a polymer, namely Soluplus® (SOL). The CD used in this series of experiments were β-cyclodextrin (βCD), hydroxypropyl-β-cyclodextrin (HPβCD) with degrees of substitution of 0.63 and 0.87, randomly methylated β-cyclodextrin (Rameb®), sulfobutylether-β-cyclodextrin (Captisol®) and methyl-β-cyclodextrin (Crysmeb®). Rheology testing and mini extrusion using a conical twin screw mini extruder were performed to test the processability of the different CD mixtures since CD are not thermoplastic. This allowed Captisol® and Crysmeb® to be discarded from the study due to their high impact on the viscosity of the SOL/ITZ mixture. The remaining CD were processed by HME in an 18mm twin screw extruder. Saturation concentration measurements confirmed the enhancement of solubility of ITZ for the four CD formulations. Biphasic dissolution tests indicated that all four formulations had faster release profiles compared to the SOL/ITZ solid dispersion. Formulations of HPβCD 0.63 and Rameb® even reached 95% of ITZ released in both phases after 1h. The formulations were characterized using thermal differential scanning calorimetry and attenuated total reflectance infra-red analysis. These analyses confirmed that the increased release profile was due to the formation of ternary inclusion complexes.

The design of functional 3D macroporous monoliths has become a necessity for a wide range of applications. The traditional post-modification strategies of porous materials are efficient but often consist of tedious multi-step processes. This work describes a straightforward macromolecular surfactant-assisted method for producing chemically functionalized macroporous polyHIPEs with interconnected structures. Accordingly, high internal phase emulsion-templated polymerizations were implemented in the presence of SG1-terminated amphiphilic copolymers prepared by nitroxide-mediated radical polymerization (NMP). The latter served as both stabilizers and functionalizing agents upon thermal activation of its terminal alkoxyamine and covalent anchoring of the released radical copolymer onto the walls of the scaffold. The effect of the polymerization temperature on the functionalization and openness of the final porous materials was explored. As a result, a range of open-cell styrene and acrylate-based polyHIPEs chemically grafted with PEO were obtained. Moreover, polyHIPEs were also decorated with alkyne-bearing PEO and subsequently modified via CuAAc click chemistry in order to demonstrate the potential of this macromolecular surfactant-assisted functionalization method.

A new photo-sensitive diblock copolymer composed of a hydrophilic sequence of poly(ethylene oxide) (PEO) linked to a CO2-philic sequence of poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) (PFDA) by a light sensitive o-nitrobenzyl group was successfully synthesized by RAFT polymerization and used as a stabilizer for the free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) dispersion in α,α,α-trifluorotoluene and supercritical carbon dioxide (scCO2). Thanks to this fluorinated stabilizer, well-defined particles of PHEMA down to 350 nm diameter were produced in scCO2. Advantageously, the photocleavable group at the block junction of the stabilizer could be cleaved by exposing the particles to UV light so that the fluorinated block could be extracted in TFT or scCO2. As supported by X-ray photoelectron spectroscopy (XPS) analysis, up to 80% of the fluorinated block of the stabilizer can be removed, leading to efficient swelling and dispersion of the resulting PHEMA nanogels in water.

Poly(hydroxyurethane) (PHU) thermosets reinforced with (functional) nanofillers were developed to design high performance adhesives for bare aluminum. Solvent-free cyclic carbonate/amine/PDMS formulations loaded with native, epoxy- or cyclic carbonate-functionalized ZnO nanofillers were premixed before deposition and thermal curing onto Al. The results highlight that the addition of PDMS prevents PHUs from delamination of the Al surface by increasing the adhesive hydrophobicity and thus limiting the water uptake. The dispersion of functional fillers within PHUs improves their thermal and mechanical properties. Benchmarking of the adhesive performances of the reinforced PHU glues with existing PHU formulations attests the benefits of dispersing functional fillers and PDMS within a resin and evidences a 270% increase of the shear strength of reinforced PHU adhesives compared to formulations reported in the literature.

Hydrogels based on polyurethane (PU) are promising (bio-) materials because of their biocompatibility, biodegradation and excellent mechanical properties. In this publication, polyurethane hydrogels were produced for the first time by a non-isocyanate route by solvent-free step-growth copolymerization between a CO2-sourced hydrophilic polyethylene glycol bi-cyclic carbonate with diamines in the presence of a cross-linker. Kinetic of poly(hydroxyurethane) (PHU) synthesis was monitored by ATR-IR and the chemical cross-linking was confirmed by rheology and gel contents measurements. Hydrogels were obtained by immersion of PHUs in water and the influence of the diamine/cross-linker ratio and the nature of diamine on the water swelling and compression properties (compression modulus, strain and stress at break) of PHU hydrogels was evaluated. Additionally, the compression properties of the hydrogels were improved by the addition of Montmorillonite as nanofiller in the PHU formulation. This work opens new application fields for CO2-sourced PHUs.

The synthesis of a series of poly(ethylene oxide)- b -polystyrene copolymers with different block lengths was performed by radical addition fragmentation chain transfer. These amphiphilic copolymers were tested as stabilizers for water-in-oil medium internal phase emulsion (MIPE) templating polymerization and the formation of polyMIPEs with controlled morphology. Aside from the structure of the emulsion stabilizer, several parameters susceptible to influence the size of the cavities and the interconnectivity of the porous monoliths were probed including the choice of the comonomers, treatment of the emulsion by ultrasound, the use of controlled radical polymerization method for the network formation as well as interfacial initiation. Interconnected cellular monoliths were produced. The polymerization of the ultrasonicated water-in-ethylhexylacrylate/divinylbenzene MIPE notably led to near-mesoporous open-cell material. Mechanical properties and specific surface areas of the polyMIPEs were also investigated and discussed.

Chemical crosslinking is an efficient tool to improve or impart new properties to conventional polymers. Especially, crosslinking imparts remarkable shape–memory properties to poly-e-caprolactone (PCL) materials. Nevertheless, the processing of networks is often tricky due to infusibility and insolubility of cross-linked chains. Therefore, the synthesis of PCL networks including thermo-reversible crosslinks based on (retro)-Diels-Alder (DA) reaction were developed to allow preserving the melt-processing while keeping the required mechanical properties below the melting point. This paper aims at studying in depth, such thermo-dependent network formation and stability. Besides conventional swelling experiments, Raman spectroscopy was revealed as a powerful tool to follow the formation of the DA adduct during the crosslinking. In combination with rheological measurements, we were able to determine the most appropriate temperatures to form the network (DA crosslinking) and to process it (retro-DA reaction) without degradation of the material.

The performances of titanium dioxide (TiO2) thin films used in photoelectrochemical applications (solar cells, water splitting, photocatalysis, etc) highly depend on their morphology and interface. In this work, we describe a straightforward strategy for designing conductive carbon-coated TiO2 porous layers allowing for the tuning of interfacial charge transfers. Increased specific surface and improved conductivity are expected from the porosity and the carbon coating, respectively. In practice, polystyrene/polyacrylonitrile (PS-PAN) and polystyrene/polydopamine (PS-PDA) core-shell particles synthesized by emulsion polymerization are considered as templating agents for the production of carbon-coated and ordered porous TiO2 layers. After spin coating deposition of the particles, infiltration of the TiO2 precursor and calcination, voids are created in the film by thermal degradation of the PS cores whereas PAN and PDA produced carbon at the surface of the TiO2 inverse opal matrix. Uncoated PS particles are also considered as benchmark templating agents. Size and composition of the polymer particles as well as the morphology and electronic properties of the corresponding porous TiO2 films are evaluated. In particular, the charge transfer resistance of the films is investigated via Electrochemical Impedance Spectroscopy (EIS) as a preliminary assessment of these unprecedented carbon-coated porous TiO2 layers as semiconducting materials.

Photochemically cross-linked shape-memory polymer (SMP) materials have been achieved by functionalizing chain-ends of star-shaped poly(ϵ-caprolactone) (PCL) with 7-hydroxypropoxy-4-methylcoumarin followed by photodimerization of these end-groups. The kinetics of the network formation in function of the photosensitizer concentration has been studied by swelling experiments and rheology. Thanks to the design of a dedicated homemade mold, highly reproducible irradiation conditions have been achieved allowing to study the network formation and properties, especially the shape-memory properties, in relation to the coumarin dimerization degree as determined by Raman spectroscopy. In optimized conditions, PCL-based SMP materials exhibiting high fixity and recovery have been achieved in remarkably short irradiation time, typically 5 min. In addition, the precise control of the network cross-link density with the irradiation time, so as the high stability of the formed networks toward temperature variations was also demonstrated allowing the fine-tuning of the network properties by the irradiation process. Finally, the reversible character of the coumarin dimerization under light irradiation of appropriate wavelength has been quantified by Raman spectroscopy. The dimer photocleavage allows the photoreconfiguration of the networks offering the ability to modify the "permanent" shape of the SMP material, while preserving the excellent shape-memory properties.

The performance of lithium and sodium ion batteries relies notably on the accessibility to carbon electrodes of controllable porous structure and chemical composition. This work reports a facile synthesis of well-defined porous N-doped carbons (NPCs) using a poly(ionic liquid) (PIL) as precursor, and graphene oxide (GO)-stabilized poly(methyl methacrylate) (PMMA) nanoparticles as sacrificial template. The GO-stabilized PMMA nanoparticles were first prepared and then decorated by a thin PIL coating before carbonization. The resulting NPCs reached a satisfactory specific surface area of up to 561 m2/g and a hierarchically meso- and macroporous structure while keeping a nitrogen content of 2.6 wt %. Such NPCs delivered a high reversible charge/discharge capacity of 1013 mA h/g over 200 cycles at 0.4 A/g for lithium ion batteries (LIBs), and showed a good capacity of 204 mA h/g over 100 cycles at 0.1 A/g for sodium ion batteries (SIBs)., Comment: 14 pages, 9 figures

Preparation of transparent and superhydrophobic coatings by co-deposition of an aqueous solution of an amphiphilic fluorinated block copolymer (FBC) with silica particles was developped. Spin-coating of this aqueous solution onto glass followed by an appropriate thermal treatment promotes the self-assembly of the hybrid material with the formation of superhydrophobic, robust and transparent coatings.

Bio- and CO2-sourced non-isocyanate polyurethane (NIPU) microcellular foams were prepared using supercritical carbon dioxide (scCO2) foaming technology. These low-density foams offer low thermal conductivity and have an impressive potential for use in insulating materials. They constitute attractive alternatives to conventional polyurethane foams. We investigated CO2's ability to synthesize the cyclic carbonates that are used in the preparation of NIPU by melt step-growth polymerization with a bio-sourced amino-telechelic oligoamide and for NIPU foaming. Our study shows that CO2 is not only sequestered in the material for long-term application, but is also valorized as a blowing agent in the production of NIPU foams. Such foams will contribute to energy conservation and savings by reducing CO2 emissions.

To explore the effectiveness of monofluorinated isoindigo as an electron-deficient building block in push-pull conjugated polymers for organic solar cell applications, four low bandgap copolymers are effectively synthesized and characterized. The effects of fluorine introduction, thiophene spacer length and polymer molar mass on the general electro-optical polymer characteristics, thin film blend microstructure and electronic performance are investigated. Isoindigo monofluorination effectively improves the power conversion efficiency from 2.8 up to 5.0% upon molar mass optimization, without using any processing additives or post-treatments.

This work investigates key parameters of a straightforward macromolecular surfactant-assisted functionalization strategy of porous polymers produced by high internal phase emulsion (HIPE) polymeriz...

Composite Crosslinked nanofibrous membranes of chitosan, ethylene glycol diglycidyl ether (EGDE) and polyethylene oxide was successfully prepared with bead free morphology via electrospinning technique followed by heat mediated chemical crosslinking. Architectural stability of nanofiber mat in aqueous medium was achieved by chemical crosslinking of only 1% EGDE, and tensile strength tests revealed that increasing EGDE content has considerably enhance the elastic modulus of nanofibers. The structure, morphology and mechanical properties of nanofibers were characterized by Attenuated Total Reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM) and Instron machine, respectively. Skin fibroblasts and endothelial cells showed good attachment, proliferation and viability on crosslinked electrospun membranes. The results indicate a good biocompatibility and non-toxic nature of the resulted membrane.

Highly expanded nanocomposite foams of polypropylene and carbon nanotubes (PP/CNT) are formed using supercritical carbon dioxide (scCO2) technology. The foaming parameters (temperature, pressure) are investigated to establish their influence on the morphology of the resulting foams and their impact on the electrical conductivity. As promising electromagnetic-interference (EMI) absorbers, the EMI shielding performance of the foams is determined, and a preliminary relationship is established between foam morphology and the EMI shielding performance. The best candidates are highly expanded foams with a volume expansion of >25, containing 0.1 vol% CNTs; they are able to absorb more than 90% of the incident radiation between 25 and 40 GHz.

This paper aims at exploring the scCO2 impregnation of three commonly implanted polymer sutures made of poly-l-lactide (PLLA), poly(ethylene terephthalate) (PET) and polypropylene (PP) with two anti-inflammatory drugs namely ketoprofen and aspirin. For all the investigated polymer/drug systems, the drug loading increases with temperature and pressure. It appears that two main criteria must be fulfilled by the polymer to achieve high drug loading: (i) a good affinity between the polymer and the drug and (ii) a high chain mobility to favor the diffusion of the drug into the matrix. As the investigated PLLA fulfills these two requirements, drug loading up to 32.5% with ketoprofen and 8.1% with aspirin has been achieved.

Sorption and diffusion of supercritical carbon dioxide (scCO2) into polycarbonate (PC) nanocomposites loaded with 0, 1 and 2 wt% of multi-walled carbon nanotubes (MWNTs) have been investigated. After determination of the saturation equilibrium, the samples have been saturated with scCO2 to ensure a partial foaming with a density gradient from the surface to the center of the samples and the morphology of the porous materials has been analysed by SEM. The gradient materials were very advantageous for EMI shielding since the foamed structure at the surface had low dielectric constant and limited the reflection of the EM signal while the presence of highly conductive solid in the middle ensured a high absorption of the electromagnetic radiation.

To establish a correlation between the molecular structure, physicochemical properties, thin film morphology, charge carrier mobility and photovoltaic performance of isoindigo-based electron donor type molecular semiconductors, a series of branched and linear A2–D–A1–D–A2 small molecules (A = acceptor, D = donor) are synthesized. The extended π-conjugated molecular chromophores have an electron-accepting isoindigo core, a bridging oligothiophene electron donor part and terminal octyl cyanoacrylate acceptor moieties. Their photophysical, thermal and electrochemical properties are analysed and the materials are applied in organic field-effect transistors and bulk heterojunction organic solar cells. Compared to an analogous benzothiadiazole-based small molecule, the isoindigo core deepens the HOMO energy level, enabling higher open-circuit voltages in organic solar cells. The linear isoindigo-based small molecule shows an enhanced hole mobility compared to the branched derivatives. The best power conversion efficiency of the investigated set is also obtained for the solar cell based on the linear (CA-3T-IID-3T-CA-l) donor molecule in combination with PC71BM.

The thermally-induced gelation and gel properties of concentrated aqueous solutions of double thermoresponsive poly(N-vinylamide)-based di- and triblock copolymers are studied by rheology. The copolymers under investigation, prepared by cobalt-mediated radical polymerization and coupling reactions, are composed of poly(vinylcaprolactam) (PNVCL) blocks and of a statistical poly(vinylcaprolactam-stat-vinylpyrrolidone) segment with a cloud point temperature (TCP) higher than that of PNVCL. Heating the di- and triblock solutions beyond the first phase transition temperature favors gel formation while heating above the second TCP leads to opaque gels without macroscopic demixing. Moduli of the triblock hydrogels are systematically higher than those of the corresponding diblocks, even above the second transition. Rheological data suggest distinct micellar structures for each copolymer architecture: densely packed micelles of diblocks and 3-D networks of bridged micelles for triblocks. Strain sweep experiments also emphasize the positive effect of the micelle bridging on the elasticity and stability of the hydrogels. The formation and properties of the obtained gels are also shown to depend on the copolymer concentration, block length, and composition. Addition of salt also allows us to tune the phase transition temperatures of these double thermoresponsive hydrogels. © 2015 The Royal Society of Chemistry.

In this paper, we describe the successful construction, characteristics and interaction with proteins of stimuli-responsive thin nanostructured films prepared by layer-by-layer (LbL) sequential assembly of PNIPAM-containing polyelectrolytes and PAH. PAA-b-PNIPAM block copolymers were synthesized in order to benefit from (i) the ionizable properties of PAA, to be involved in the LbL assembly, and (ii) the sensitivity of PNIPAM to temperature stimulus. The impact of parameters related to the structure and size of the macromolecules (their molecular weight and the relative degree of polymerization of PAA and PNIPAM), and the interaction with proteins under physico-chemical stimuli, such as pH and temperature, are carefully investigated. The incorporation of PAA-b-PNIPAM into multilayered films is shown to be successful whatever the block copolymer used, resulting in slightly thicker films than the corresponding (PAA/PAH)n film. Importantly, the protein adsorption studies demonstrate that it is possible to alter the adsorption behavior of proteins on (PAA-b-PNIPAM/PAH)n surfaces by varying the temperature and/or the pH of the medium, which seems to be intimately related to two key factors: (i) the ability of PNIPAM units to undergo conformational changes and (ii) the structural changes of the film made of weak polyelectrolytes. The simplicity of construction of these PNIPAM block copolymer-based LbL coatings on a large range of substrates, combined with their highly tunable features, make them ideal candidates to be employed for various biomedical applications requiring the control of protein adsorption.

The implementation of cobalt-mediated radical polymerization (CMRP) for continuous microreactor synthesis is described. We demonstrate how the utilization of flow photoreactors allows the speed up of the polymerization of vinyl acetate (VAc) under UV irradiation without loss of polymerization control. Microfluidics under UV irradiation has also been successfully implemented for the copolymerization of VAc with a less reactive olefin 1-octene (1-Oct). Reactivity ratios were deduced for this copolymerization system, and poly(VAc-co-1-Oct) copolymers containing up to 50 mol% of 1-Oct were synthesized. To the best of our knowledge, this is the first report on a photopolymerization where continuous flow techniques not only led to an improvement of reaction rates and dispersity, but also led to the avoidance of significant side-products that were observed in batch processing.