Cover Picture: Novel Photoactive Single‐Walled Carbon Nanotube–Porphyrin Polymer Wraps: Efficient and Long‐Lived Intracomplex Charge Separation (Adv. Mater. 7/2005)

The figure on the cover portrays a novel donor–acceptor nanoassembly, based on a single‐walled carbon nanotube (SWNT) as the electron acceptor and poly(methyl methacrylate) (PMMA)‐carrying porphyrin units (H2P) as the excited‐state electron donors. In these supramolecular “polymer wraps”, reported on p. 871 by Guldi and co‐workers, SWNTs quench the photoexcited H2P chromophores, resulting in the creation of microsecond‐lived radical ion pairs.     

Proteolytically Degradable Photo‐Polymerized Hydrogels Made From PEG–Fibrinogen Adducts

We develop a biomaterial based on protein–polymer conjugates where poly(ethylene glycol) (PEG) polymer chains are covalently linked to multiple thiols on denatured fibrinogen. We hypothesize that conjugation of large diacrylate‐functionalized linear PEG chains to fibrinogen could govern the molecular architecture of the polymer network via a unique protein–polymer interaction. The hypothesis is explored using carefully designed shear rheometry and swelling experiments of the hydrogels and their precursor PEG/fibrinogen conjugate solutions. The physical properties of non‐cross‐linked and UV cross‐linked PEGylated fibrinogen having PEG molecular weights ranging from 10 to 20 kDa are specifically investigated. Attaching multiple hydrophilic, functionalized PEG chains to the denatured fibrinogen solubilizes the denatured protein and enables a rapid free‐radical polymerization cross‐linking reaction in the hydrogel precursor solution. As expected, the conjugated protein‐polymer macromolecular complexes act to mediate the interactions between radicals and unsaturated bonds during the free‐radical polymerization reaction, when compared to control PEG hydrogels. Accordingly, the cross‐linking kinetics and stiffness of the cross‐linked hydrogel are highly influenced by the protein–polymer conjugate architecture and molecular entanglements arising from hydrophobic/hydrophilic interactions and steric hindrances. The proteolytic degradation products of the protein–polymer conjugates proves to be were different from those of the non‐conjugated denatured protein degradation products, indicating that steric hindrances may alter the proteolytic susceptibility of the PEG–protein adduct. A more complete understanding of the molecular complexities associated with this type of protein‐polymer conjugation can help to identify the full potential of a biomaterial that combines the advantages of synthetic polymers and bioactive proteins.     

Aromatic‐Diimide‐Based n‐Type Conjugated Polymers for All‐Polymer Solar Cell Applications

All‐polymer solar cells (all‐PSCs) have attracted immense attention in recent years due to their advantages of tunable absorption spectra and electronic energy levels for both donor and acceptor polymers, as well as their superior thermal and mechanical stability. The exploration of the novel n‐type conjugated polymers (CPs), especially based on aromatic diimide (ADI), plays a vital role in the further improvement of power conversion efficiency (PCE) of all‐PSCs. Here, recent progress in structure modification of ADIs including naphthalene diimide (NDI), perylene diimide (PDI), and corresponding derivatives is reviewed, and the structure–property relationships of ADI‐based CPs are revealed.     

A Polymer‐Reinforced SEI Layer Induced by a Cyclic Carbonate‐Based Polymer Electrolyte Boosting 4.45 V LiCoO2/Li Metal Batteries

Lithium (Li) metal batteries (LMBs) are enjoying a renaissance due to the high energy densities. However, they still suffer from the problem of uncontrollable Li dendrite and pulverization caused by continuous cracking of solid electrolyte interphase (SEI) layers. To address these issues, developing spontaneously built robust polymer‐reinforced SEI layers during electrochemical conditioning can be a simple yet effective solution. Herein, a robust homopolymer of cyclic carbonate urethane methacrylate is presented as the polymer matrix through an in situ polymerization method, in which cyclic carbonate units can participate in building a stable polymer‐integrated SEI layer during cycling. The as‐investigated gel polymer electrolyte (GPE) assembled LiCoO₂/Li metal batteries exhibit a fantastic cyclability with a capacity retention of 92% after 200 cycles at 0.5 C (1 C = 180 mAh g^?1), evidently exceeding that of the counterpart using liquid electrolytes. It is noted that the anionic ring‐opening polymerization of the cyclic carbonate units on the polymer close to the Li metal anodes enables a mechanically reinforced SEI layer, thus rendering excellent compatibility with Li anodes. The in situ formed polymer‐reinforced SEI layers afford a splendid strategy for developing high voltage resistant GPEs compatible with Li metal anodes toward high energy LMBs.     

Iodine‐Rich Semiconducting Polymer Nanoparticles for CT/Fluorescence Dual‐Modal Imaging‐Guided Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) is a promising technique for cancer therapy, providing good therapeutic efficacy with minimized side effect. However, the lack of oxygen supply in the hypoxic tumor site obviously restricts the generation of singlet oxygen (¹O₂), thus limiting the efficacy of PDT. So far, the strategies to improve PDT efficacy usually rely on complicated nanosystems, which require sophisticated design or complex synthetic procedure. Herein, iodine‐rich semiconducting polymer nanoparticles (SPN‐I) for enhanced PDT, using iodine‐induced intermolecular heavy‐atom effect to elevate the ¹O₂ generation, are designed and prepared. The nanoparticles are composed of a near‐infrared (NIR) absorbing semiconducting polymer (PCPDTBT) serving as the photosensitizer and source of fluorescence signal, and an iodine‐grafted amphiphilic diblock copolymer (PEG‐PHEMA‐I) serving as the ¹O₂ generation enhancer and nanocarrier. Compared with SPN composed of PEG‐b‐PPG‐b‐PEG and PCPDTBT (SPN‐P), SPN‐I can enhance the ¹O₂ generation by 1.5‐fold. In addition, SPN‐I have high X‐ray attenuation coefficient because of the high density of iodine in PEG‐PHEMA‐I, providing SPN‐I the ability of use with computed tomography (CT) and fluorescence dual‐modal imaging. The study thus provides a simple nanotheranostic platform composed of two components for efficient CT/fluorescence dual‐modal imaging‐guided enhanced PDT.     

Stabilization of Polymer‐Hydrogel Capsules via Thiol–Disulfide Exchange

Polymer hydrogels are used in diverse biomedical applications including drug delivery and tissue engineering. Among different chemical linkages, the natural and reversible thiol–disulfide interconversion is extensively explored to stabilize hydrogels. The creation of macro‐, micro‐, and nanoscale disulfide‐stabilized hydrogels commonly relies on the use of oxidizing agents that may have a detrimental effect on encapsulated cargo. Herein an oxidization‐free approach to create disulfide‐stabilized polymer hydrogels via a thiol–disulfide exchange reaction is reported. In particular, thiolated poly(methacrylic acid) is used and the conditions of polymer crosslinking in solution and on colloidal porous and solid microparticles are established. In the latter case, removal of the core particles yields stable, hollow, disulfide‐crosslinked hydrogel capsules. Further, a procedure is developed to achieve efficient disulfide crosslinking of multilayered polymer films to obtain stable, liposome‐loaded polymer‐hydrogel capsules that contain functional enzymatic cargo within the liposomal subcompartments. This approach is envisaged to facilitate the development of biomedical applications of hydrogels, specifically those including fragile cargo.     

Electrospray Encapsulation of Hydrophilic and Hydrophobic Drugs in Poly(L‐lactic acid) Nanoparticles

An electrospray method is developed for preparation of beclomethasone‐dipropionate‐ and salbutamol‐sulfate‐loaded biodegradable poly(L ‐lactic acid) nanoparticles. Different set‐up parameters for electrospraying are examined on particle size, and preparation conditions are optimized for producing spherical‐drug‐loaded nanoscale particles by controllable processing parameters. Polylactide (PLA)–drug nanoparticles with average diameters of around 200 nm are achieved in a stable cone‐jet mode with a flow rate of 4 µL min^?1, polymer concentration of 1%, and ammonium hydroxide content of 0.05%. Morphology and size of the drug–polymer nanoparticles are analyzed by scanning electron microscopy and transmission electron microscopy. Changes in the crystallinity of the PLA polymer and the model drugs are detected by X‐ray powder diffraction, and the absence of molecular interactions are confirmed by thermal analyses. The results indicate clearly that electrospraying is a potential method for producing polymeric nanoparticles and for encapsulating both hydrophilic and hydrophobic drugs efficiently into the nanoparticles.     

Click‐Chemistry Based Multi‐Component Microarrays by Quill‐Like Pens

We demonstrate the generation of multi‐component spot microarrays by blotting different ink solutions via quill‐like pens. The obtained arrays are immobilized by click‐chemistry in form of the copper(I)‐catalyzed azide‐alkyne cycloaddition and remain stable against washing and immersion in aqueous solution. The average spot radius ranges from 10 to 20 μm and is about an order of magnitude smaller than in currently commercially applied arraying techniques, effectively bridging the gap to high resolution methods as dip‐pen nanolithography and polymer pen lithography. The use of the quill‐like‐pen‐generated spot microarrays as binding assay is demonstrated by capturing of streptavidin from solution and by bioactive sandwich structures from neutravidin and biotin‐labeled fibronectin. Thus, our multi‐component spot microarrays have ideal dimensions and biochemical properties to accommodate (single) cells. Additionally, the building up of the cell‐recruiting protein sandwich structure on top of the basic spot microarray allows for the highly selective adhesion of fibroblasts. This results then in ordered (single) cell arrays, demonstrating the bio‐compatibility and high throughput of this multi‐component spot microarray platform.     

Adhesion mechanism of salmon to polymer‐coated can walls

Minimization of the amount of salmon adhering to the can wall after emptying is one of the convenience requirements of consumers of canned salmon. In order to achieve this, the mechanism by which salmon adheres to cans needs to be understood. The aim of this study was to provide such knowledge for polymer‐coated cans. The results indicate that gelatin, derived from salmon collagen, and myofibrillar proteins are the major proteins involved in sticking of salmon to the polymer‐coated can wall. Furthermore, it was shown that mainly hydrogen bonds are formed between the salmon proteins and the polymer surface. Therefore, making the surface more apolar can prevent sticking of salmon to polymer‐coated cans. Copyright © 2005 John Wiley & Sons, Ltd.     

Fluorescent Polymer—Single‐Walled Carbon Nanotube Complexes with Charged and Noncharged Dendronized Perylene Bisimides for Bioimaging Studies

Fluorescent nanomaterials are expected to revolutionize medical diagnostic, imaging, and therapeutic tools due to their superior optical and structural properties. Their inefficient water solubility, cell permeability, biodistribution, and high toxicity, however, limit the full potential of their application. To overcome these obstacles, a water‐soluble, fluorescent, cytocompatible polymer—single‐walled carbon nanotube (SWNT) complex is introduced for bioimaging applications. The supramolecular complex consists of an alkylated polymer conjugated with neutral hydroxylated or charged sulfated dendronized perylene bisimides (PBIs) and SWNTs as a general immobilization platform. The polymer backbone solubilizes the SWNTs, decorates them with fluorescent PBIs, and strongly improves their cytocompatibility by wrapping around the SWNT scaffold. In photophysical measurements and biological in vitro studies, sulfated complexes exhibit superior optical properties, cellular uptake, and intracellular staining over their hydroxylated analogs. A toxicity assay confirms the highly improved cytocompatibility of the polymer‐wrapped SWNTs toward surfactant‐solubilized SWNTs. In microscopy studies the complexes allow for the direct imaging of the SWNTs' cellular uptake via the PBI and SWNT emission using the 1st and 2nd optical window for bioimaging. These findings render the polymer‐SWNT complexes with nanometer size, dual fluorescence, multiple charges, and high cytocompatibility as valuable systems for a broad range of fluorescence bioimaging studies.     

Critical Analysis of Fibre‐Reinforced Polymer Near‐Surface Mounted Double‐shear Pull‐out Tests

The study of the bond behaviour between fibre‐reinforced polymer (FRP) systems and concrete is an issue that nowadays attracts many researchers. The scientific community dedicated to the research of FRP reinforcement has been conducting numerous experimental programmes aiming to assess the local bond–slip law of the FRP–adhesive–concrete connection. This paper reports the relevant results obtained by the Structural Composite Research Group of Minho University in the scope of an international Round Robin Test. The suitability of the recommended test setup to derive a local bond constitutive law for modelling the bond behaviour of near‐surface mounted reinforcement systems is discussed based on a deep interpretation of the results.     

3D Printing All‐Aromatic Polyimides using Mask‐Projection Stereolithography: Processing the Nonprocessable

High‐performance, all‐aromatic, insoluble, engineering thermoplastic polyimides, such as pyromellitic dianhydride and 4,4′‐oxydianiline (PMDA–ODA) (Kapton), exhibit exceptional thermal stability (up to ≈600 °C) and mechanical properties (Young's modulus exceeding 2 GPa). However, their thermal resistance, which is a consequence of the all‐aromatic molecular structure, prohibits processing using conventional techniques. Previous reports describe an energy‐intensive sintering technique as an alternative technique for processing polyimides with limited resolution and part fidelity. This study demonstrates the unprecedented 3D printing of PMDA–ODA using mask‐projection stereolithography, and the preparation of high‐resolution 3D structures without sacrificing bulk material properties. Synthesis of a soluble precursor polymer containing photo‐crosslinkable acrylate groups enables light‐induced, chemical crosslinking for spatial control in the gel state. Postprinting thermal treatment transforms the crosslinked precursor polymer to PMDA–ODA. The dimensional shrinkage is isotropic, and postprocessing preserves geometric integrity. Furthermore, large‐area mask‐projection scanning stereolithography demonstrates the scalability of 3D structures. These unique high‐performance 3D structures offer potential in fields ranging from water filtration and gas separation to automotive and aerospace technologies.     

Super‐Resolution Mapping of Single Nanoparticles inside Tumor Spheroids

Cancer spheroids have structural, functional, and physiological similarities to the tumor, and have become a low‐cost in vitro model to study the physiological responses of single cells and therapeutic efficacy of drugs. However, the tiny spheroid, made of a cluster of high‐density cells, is highly scattering and absorptive, which prevents light microscopy techniques to reach the depth inside spheroids with high resolution. Here, a method is reported for super‐resolution mapping of single nanoparticles inside a spheroid. It first takes advantage of the self‐healing property of a “nondiffractive” doughnut‐shaped Bessel beam from a 980 nm diode laser as the excitation, and further employs the nonlinear response of the 800 nm emission from upconversion nanoparticles, so that both excitation and emission at the near‐infrared can experience minimal loss through the spheroid. These strategies lead to the development of a new nanoscopy modality with a resolution of 37 nm, 1/26th of the excitation wavelength. This method enables mapping of single nanoparticles located 55 µm inside a spheroid, with a resolution of 98 nm. It suggests a solution to track single nanoparticles and monitor their release of drugs in 3D multicellar environments.     

Nanoscale Probing of a Polymer‐Blend Thin Film with Tip‐Enhanced Raman Spectroscopy

Fundamental advances have been made in the spatially resolved chemical analysis of polymer thin films. Tip‐enhanced Raman spectroscopy (TERS) is used to investigate the surface composition of a mixed polyisoprene (PI) and polystyrene (PS) thin film. High‐quality TER spectra are collected from these nonresonant Raman‐active polymers. A wealth of structural information is obtained, some of which cannot be acquired with conventional analytical techniques. PI and PS are identified at the surface and subsurface, respectively. Differences in the band intensities suggest strongly that the polymer layers are not uniformly thick, and that nanopores are present under the film surface. The continuous PS subsurface layer and subsurface nanopores have hitherto not been identified. These data are obtained with nanometer spatial resolution. Confocal far‐field Raman spectroscopy and X‐ray photoelectron spectroscopy are employed to corroborate some of the results. With routine production of highly enhancing TERS tips expected in the near future, it is predicted that TERS will be of great use for the rigorous chemical analysis of polymer and other composite systems with nanometer spatial resolution.     

Universal Route to Impart Orthogonality to Polymer Semiconductors for Sub‐Micrometer Tandem Electronics

A universal method that enables utilization of conventional photolithography for processing a variety of polymer semiconductors is developed. The method relies on imparting chemical and physical orthogonality to a polymer film via formation of a semi‐interpenetrating diphasic polymer network with a bridged polysilsesquioxane structure, which is termed an orthogonal polymer semiconductor gel. The synthesized gel films remain tolerant to various chemical and physical etching processes involved in photolithography, thereby facilitating fabrication of high‐resolution patterns of polymer semiconductors. This method is utilized for fabricating tandem electronics, including pn‐complementary inverter logic devices and pixelated polymer light‐emitting diodes, which require deposition of multiple polymer semiconductors through solution processes. This novel and universal method is expected to significantly influence the development of advanced polymer electronics requiring sub‐micrometer tandem structures.     

A Temperature‐Responsive Boronate Core Cross‐Linked Star (CCS) Polymer for Fast and Highly Efficient Enrichment of Glycoproteins

Fast and highly efficient enrichment and separation of glycoproteins is essential in many biological applications, but the lack of materials with high capture capacity, fast, and efficient enrichment/separation makes it a challenge. Here, a temperature‐responsive core cross‐linked star (CCS) polymer with boronate affinity is reported for fast and efficient enriching and separating of glycoproteins from biological samples. The temperature‐responsive CCS polymers containing boronic acid in its polymeric arms and poly(N‐isopropyl acrylamide) in its cross‐linked core are prepared using reversible addition‐fragmentation chain transfer polymerization via an “arm‐first” methodology. The soluble boronate polymeric arms of the CCS polymers provide a homogeneous reaction system and facilitate interactions between boronic acid and glycoproteins, which leads to a fast binding/desorption speed and high capture capacity. Maximum binding capacity of the prepared CCS polymer for horseradish peroxidase is determined to be 210 mg g^?1, which can be achieved within 20 min. More interestingly, the temperature‐responsive CCS polymers exhibit rapid reversible thermal‐induced volume phase transition by increasing the temperature from 15 to 30 °C, resulting in a facile and convenient sample collection and recovery for the target glycoproteins. Finally, the temperature‐responsive CCS polymer is successfully applied to enrichment of low abundant glycoproteins.     

A Free‐Standing and Self‐Healable 2D Supramolecular Material Based on Hydrogen Bonding: A Nanowire Array with Sub‐2‐nm Resolution

In many 2D materials reported thus far, the forces confining atoms in a 2D plane are often strong interactions, such as covalent bonding. Herein, the first demonstration that hydrogen (H)‐bonding can be utilized to assemble polydiacetylene (a conductive polymer) toward a 2D material, which is stable enough to be free‐standing, is shown. The 2D material is well characterized by a large number of techniques (mainly different microscopy techniques). The H‐bonding allows splitting of the material into ribbons, which can reassemble, similar to a zipper, leading to the first example of a healable 2D material. Moreover, such technology can easily create 2D, organic, conductive nanowire arrays with sub‐2‐nm resolution. This material may have potential applications in stretchable electronics and nanowire cross‐bar arrays.     

Progress with Light‐Emitting Polymers

Light‐emitting polymers have been studied intensively as materials for light‐emitting diodes (LEDs). Here research efforts toward developing these materials for commercial applications are reviewed. The Figure shows the preferred two‐layer device structure for commercial polymer LEDs as well as polyfluorene, one of the polymers discussed.     

High‐Entropy Alloy (HEA)‐Coated Nanolattice Structures and Their Mechanical Properties

Nanolattice structure fabricated by two‐photon lithography (TPL) is a coupling of size‐dependent mechanical properties at micro/nano‐scale with structural geometry responses in wide applications of scalable micro/nano‐manufacturing. In this work, three‐dimensional (3D) polymeric nanolattices are initially fabricated using TPL, then conformably coated with an 80 nm thick high‐entropy alloy (HEA) thin film (CoCrFeNiAl_0.3) via physical vapor deposition (PVD). 3D atomic‐probe tomography (APT) reveals the homogeneous element distribution in the synthesized HEA film deposited on the substrate. Mechanical properties of the obtained composite architectures are investigated via in situ scanning electron microscope (SEM) compression test, as well as finite element method (FEM) at the relevant length scales. The presented HEA‐coated nanolattice encouragingly not only exhibits superior compressive specific strength of ≈0.032 MPa kg^?1 m³ with density well below 1000 kg m^?3, but also shows good compression ductility due to its composite nature. This concept of combining HEA with polymer lattice structures demonstrates the potential of fabricating novel architected metamaterials with tunable mechanical properties.

     

Large‐Area,Uniform, Aligned Arrays of Na3(VO)2(PO4)2F on Carbon Nanofiber for Quasi‐Solid‐State Sodium‐Ion Hybrid Capacitors

Sodium–vanadium fluorophosphate (Na₃V₂O_2x(PO₄)₂F_3?2x, NVPF, 0 ≤ x ≤ 1) is considered to be a promising Na‐storage cathode material due to its high operation potentials (3.6–4 V) and minor volume variation (1.8%) during Na⁺‐intercalation. Research about NVPF is mainly focused on powder‐type samples, while its ordered array architecture is rarely reported. In this work, large‐area and uniform Na₃(VO)₂(PO₄)₂F cuboid arrays are vertically grown on carbon nanofiber (CNF) substrates for the first time. Owing to faster electron/ion transport and larger electrolyte–electrode contact area, the as‐prepared NVPF array electrode exhibits much improved Na‐storage properties compared to its powder counterpart. Importantly, a quasi‐solid‐state sodium‐ion hybrid capacitor (SIHC) is constructed based on the NVPF array as an intercalative battery cathode and porous CNF as a capacitive supercapacitor anode together with the P(VDF‐HFP)‐based polymer electrolyte. This novel hybrid system delivers an attractive energy density of ≈227 W h kg^?1 (based on total mass of two electrodes), and still remains as high as 107 Wh kg^?1 at a high specific power of 4936 W kg^?1, which pushes the energy output of sodium hybrid capacitors toward a new limit. In addition, the growth mechanism of NVPF arrays is investigated in detail.