Anion‐exchange membrane fuel cells (AEMFCs) are a promising, next‐generation fuel cell technology. AEMFCs require highly conductive and robust anion‐exchange membranes (AEMs), which are challenging ...to develop due to the tradeoff between conductivity and water uptake. Here we report a method to prepare high‐molecular‐weight branched poly(aryl piperidinium) AEMs. We show that branching reduces water uptake, leading to improved dimensional stability. The optimized membrane, b‐PTP‐2.5, exhibits simultaneously high OH− conductivity (>145 mS cm−1 at 80 °C), high mechanical strength and dimensional stability, good processability, and excellent alkaline stability (>1500 h) in 1 M KOH at 80 °C. AEMFCs based on b‐PTP‐2.5 reached peak power densities of 2.3 W cm−2 in H2−O2 and 1.3 W cm−2 in H2‐air at 80 °C. The AEMFCs can run stably under a constant current of 0.2 A cm−2 over 500 h, during which the b‐PTP‐2.5 membrane remains stable.
High‐molecular‐weight branched poly(aryl piperidinium) membranes with high conductivity (147 mS cm−1 at 80 °C) and excellent mechanical (26 % swelling ratio) and chemical stability have been prepared. Anion‐exchange membrane fuel cells (AEMFCs) using these membranes exhibit high peak power density (2.3 W cm−2) and durability (500 h).
Anion‐exchange‐membrane fuel cells (AEMFCs) are a cost‐effective alternative to proton‐exchange‐membrane fuel cells (PEMFCs). The development of high‐performance and durable AEMFCs requires highly ...conductive and robust anion‐exchange membranes (AEMs). However, AEMs generally exhibit a trade‐off between conductivity and dimensional stability. Here, a fluorination strategy to create a phase‐separated morphological structure in poly(aryl piperidinium) AEMs is reported. The highly hydrophobic perfluoroalkyl side chains augment phase separation to construct interconnected hydrophilic channels for anion transport. As a result, these fluorinated PAP (FPAP) AEMs simultaneously possess high conductivity (>150 mS cm−1 at 80 °C) and high dimensional stability (swelling ratio <20% at 80 °C), excellent mechanical properties (tensile strength >80 MPa and elongation at break >40%) and chemical stability (>2000 h in 3 m KOH at 80 °C). AEMFCs with a non‐precious Co–Mn spinel cathode using the present FPAP AEMs achieve an outstanding peak power density of 1.31 W cm−2. The AEMs remain stable over 500 h of fuel cell operation at a constant current density of 0.2 A cm−2.
Side‐chain fluorination leads to poly(aryl piperidinium) membranes with both high conductivity and high dimensional stability. These membranes are stable over 500 h in anion‐exchange‐membrane fuel cells (AEMFCs) with a PGM‐free (Co–Mn spinel) cathode.
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Advances in controlled radical polymerization over the past two decades have transformed the ability to produce molecularly well-defined, chain-end tethered polymer brush films. The ...assets of controlled radical polymerization reactions have impacted the synthesis and properties of surface-grafted polymer brushes in various ways. This review article will highlight two aspects related to the preparation and use of polymer brush film that have benefited from these advances. The first part of this review will illustrate how surface-initiated controlled radical polymerization chemistries have allowed access to surface-grafted polymers with complex topologies. The second part of this article will discuss the use of surface-initiated controlled radical polymerization to prepare polymer brush-nanoparticle hybrid films.
The exploration of renewable resources is essential to help transition toward a more sustainable materials economy. The valorization of lignin can be a key component of this transition. Lignin is an ...aromatic polymer that constitutes approximately one-third of the total lignocellulosic biomass and is isolated in huge quantities as a waste material of biofuel and paper production. About 98% of the 100 million tons of lignin produced each year is simply burned as low-value fuel, so this renewable polymer is widely available at very low cost. Lignin has valuable properties that make it a promising material for numerous applications, but it is far from being fully exploited. The aim of this Perspective is to highlight opportunities and challenges for the use of lignin-based materials in food packaging, antimicrobial, and agricultural applications. In the first part, the ongoing research and the possible future developments for the use of lignin as an additive to improve mechanical, gas and UV barrier, and antioxidant properties of food packaging items will be treated. Second, the application of lignin as an antimicrobial agent will be discussed to elaborate on the activity of lignin against bacteria, fungi, and viruses. Finally, the use of lignin in agriculture will be presented by focusing on the application of lignin as fertilizer.
Bacteria represent a class of living cells that are very attractive carriers for the transport and delivery of nano‐ and microsized particles. The use of cell‐based carriers, such as for example ...bacteria, may allow to precisely direct nano‐ or microsized cargo to a desired site, which would greatly enhance the selectivity of drug delivery and allow to mitigate side effects. One key step towards the use of such nano‐/microparticle – bacteria hybrids is the immobilization of the cargo on the bacterial cell surface. To fabricate bacteria – nano‐/microparticle biohybrid microsystems, a wide range of chemical approaches are available that can be used to immobilize the particle payload on the bacterial cell surface. This article presents an overview of the various covalent and noncovalent chemistries that are available for the preparation of bacteria – nano‐/microparticle hybrids. For each of the different chemical approaches, an overview will be presented that lists the bacterial strains that have been modified, the type and size of nanoparticles that have been immobilized, as well as the methods that have been used to characterize the nanoparticle‐modified bacteria.
Bacteria are a very attractive class of carriers for the transport of nanoparticles. This article presents an overview of the chemical approaches that are available for the preparation of bacteria – nano‐/microparticle hybrids.
Abstract In the past decades, polymeric nanoparticles have emerged as a most promising and viable technology platform for targeted and controlled drug delivery. As vehicles, ideal nanoparticles are ...obliged to possess high drug loading levels, deliver drug to the specific pathological site and/or target cells without drug leakage on the way, while rapidly unload drug at the site of action. To this end, various “intelligent” polymeric nanoparticles that release drugs in response to an internal or external stimulus such as pH, redox, temperature, magnetic and light have been actively pursued. These stimuli-responsive nanoparticles have demonstrated, though to varying degrees, improved in vitro and/or in vivo drug release profiles. In an effort to further improve drug release performances, novel dual and multi-stimuli responsive polymeric nanoparticles that respond to a combination of two or more signals such as pH/temperature, pH/redox, pH/magnetic field, temperature/reduction, double pH, pH and diols, temperature/magnetic field, temperature/enzyme, temperature/pH/redox, temperature/pH/magnetic, pH/redox/magnetic, temperature/redox/guest molecules, and temperature/pH/guest molecules have recently been developed. Notably, these combined responses take place either simultaneously at the pathological site or in a sequential manner from nanoparticle preparation, nanoparticle transporting pathways, to cellular compartments. These dual and multi-stimuli responsive polymeric nanoparticles have shown unprecedented control over drug delivery and release leading to superior in vitro and/or in vivo anti-cancer efficacy. With programmed site-specific drug delivery feature, dual and multi-stimuli responsive nanoparticulate drug formulations have tremendous potential for targeted cancer therapy. In this review paper, we highlight the recent exciting developments in dual and multi-stimuli responsive polymeric nanoparticles for precision drug delivery applications, with a particular focus on their design, drug release performance, and therapeutic benefits.
Post-polymerization modification is based on the direct polymerization or copolymerization of monomers bearing chemoselective handles that are inert towards the polymerization conditions but can be ...quantitatively converted in a subsequent step into a broad range of other functional groups. The success of this method is based on the excellent conversions achievable under mild conditions, the excellent functional-group tolerance, and the orthogonality of the post-polymerization modification reactions. This Review surveys different classes of reactive polymer precursors bearing chemoselective handles and discusses issues related to the preparation of these reactive polymers by direct polymerization of appropriately functionalized monomers as well as the post-polymerization modification of these precursors into functional polymers.
Polymer nanomedicines are very attractive to improve the delivery of chemotherapeutics. Polymer conjugates and other polymer‐based nanocarriers allow to increase plasma half‐life and drug ...bioavailability and can also be guided toward tumors using passive and active targeting strategies. Since many chemotherapeutics act on targets that are located in well‐defined subcellular compartments, other important factors that contribute to an efficient therapy include cellular internalization and subsequent intracellular trafficking of the polymer nanomedicines and/or its payload to the appropriate organelle in the cytoplasm. This article provides an overview of the different approaches that have been developed to control intracellular delivery of polymer nanomedicines and discusses the different techniques that can be used to monitor these processes.
Control over the intracellular delivery of drugs is crucial for their therapeutic efficiency. This article presents the approaches that have been developed to control delivery of polymer nanomedicines to specific subcellular compartments (the cytoplasm, the mitochondria, the Golgi apparatus, the endoplasmic reticulum, the nucleus) as well as the methods that have been used to monitor these processes.
Cell mediated delivery of synthetic nano- and microparticle based drug carriers is a very promising strategy to enhance control over the distribution of drugs and improve targeting. This article will ...present an overview of work, which has been done to explore cell surface modification strategies for the cellular hitchhiking of synthetic nano- and microparticles. The first part of this article will present and discuss the different types of cells that have been explored for cell mediated drug delivery. The second part of this review will discuss the various chemical strategies that have been elaborated for the conjugation or immobilization of nano- and microparticles on the surface of these cells.
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