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Minimizing the use of Pt catalysts in proton exchange membrane fuel cells (PEMFCs) is important, considering its high price and scarcity. Herein, we demonstrate novel catalysts for PEMFCs with exceptionally high mass activity and durability, in which block copolymer-based carbon supports are loaded with an ultra-small amount of Pt. The mass activity measured after 30 000 cycles of single cell tests was 0.81 A mgPt−1 at 0.9 V, which is the highest performance reported to date. The newly developed catalyst yielded nearly the same power density as that of the commercial Pt/C, even with 1/20 of the Pt usage. The carbon supports were prepared by carbonizing crosslinked domains of block copolymer particles selectively, resulting in mesoporous carbon particles with ∼25 nm pores. When Pt was deposited, thin carbon shells were formed encapsulating PtFe nanoparticles, catalyzing the oxygen reduction reaction efficiently with high durability.

In this work, thermal conductivity and mechanical strength of a commercial epoxy resin were improved by incorporating an amine-terminated oligoimide modified graphene oxide (ATO-GO). For this purpose, the surface of GO was modified with flexible/stable imide backbone and amine terminals. The ATO-GO was incorporated in epoxy proportion to prepare series of nanocomposites. The terminal amino group of ATO-GO also acted as curing moiety for epoxy resin leading to good interfacial compatibility and dispersion in the epoxy matrix resulting in improved properties. The epoxy resin was cured with hardener Aradur-22962 and ATO-GO separately and the results of curing behavior were compared with each other, which clearly showed the curing action of ATO-GO. In the prepared ATO-GO-epoxy nanocomposites, the filler enhanced the thermal conductivity, hardness and elastic modulus without decrease in thermal stability even at higher filler loading. In previous studies, it is reported that at higher GO, filler-loading properties like elastic modulus, hardness values, and glass transition temperature ( T g) were decreased. An enhancement of 59.5% in thermal conductivity was achieved for 5 wt% loading of ATO-GO filler as compared to neat epoxy. Along with this, thermal analysis revealed that the nanocomposites with 5 wt% filler loading have high T g and thermal strength. Nanoindentation results revealed that elastic modulus and hardness values enhanced by 104% and 147%, respectively, for the same nanocomposites. The enhanced thermal conductivity and good elastic behavior of the ATO-GO-epoxy nanocomposites demonstrated that these can be used as high-performance materials in electronic packing and electronic devices.

The use of lithium (Li) metal anodes in solid-state batteries is a strong strategy as a next-generation battery technology for surpassing the energy density and safety of conventional Li-ion batteries. However, in practice, current solid-state electrolytes have been limited to realize Li metal batteries due to their insufficient electrochemical and mechanical properties. Here, we design a new class of elastomeric electrolytes having a 3D interconnected plastic-crystal phase within the elastomer matrix—plastic crystal-embedded elastomer electrolytes (PCEEs).1 To elucidate the effects of structural changes in PCEEs on Li-ion transport property, mechanical elasticity, and electrochemical performance, we investigate various phase-separated structures of PCEEs by adjusting each phase’s volume ratio. Among these structures, we reveal that bicontinuous-structured PCEE, consisting of an equal volume ratio of elastomer to plastic-crystal phase, is well-balanced to develop the efficient ion-conducting, plastic-crystal pathways within a mechanically robust, cross-linked elastomer matrix. Hence, this optimal PCEE shows a combination of high ionic conductivity (>10-3 S cm-1) at ambient temperature, high Li-ion transference number (>0.70), and good mechanical resilience (elongation at break ≈ 300%). A full cell configured with the optimized PCEE, a limited Li source, and a high loading LiNi0.83Mn0.6Co1.1O2 cathode delivers a high energy density exceeding 430 Wh kganode+cathode+electrolyte -1. Understanding the structure-property-electrochemical performance relationship of PCEE through structural control can form the basis of structure-controlled elastomeric electrolytes, holding substantial promise in various electrochemical energy storage systems. References 1. Lee, M. J.; Han, J.; Lee, K.; Lee, Y. J.; Kim, B. G.; Jung, K.-N; Kim, B. J.; Lee, S. W. Elastomeric electrolytes for high-energy solid-state lithium batteries. Nature 2022, 601, 217-222.

In this work, we develop mechanically robust and high-performance organic thin-film transistors (OTFTs) based on poly(3-hexylthiophene) (P3HT) regioblock copolymers (block-P3HTs). These block-P3HTs...

We examined the packing structure of polystyrene-coated gold nanoparticles (Au@PS) as a function of grafting density. A series of Au@PS nanoparticles with grafting densities in the range of 0.51–1.94 chains nm–2 were prepared by a ligand exchange process using thiol-terminated PS and then self-assembled at a liquid–air interface. We observed a transition from disordered to body-centered cubic (bcc) to face-centered cubic (fcc) arrangements with increasing grafting density, even though the ligand length-to-core radius ratio (λ) was as high as 3.0, a condition that typically favors nonclose-packed bcc symmetry in the self-assembly of hard nanoparticles. To explain this phenomenon, we define λeff to include the concentrated polymer brush regime as part of the “hard core”, which predicts that the softness of Au@PS nanoparticles is reduced from 1.53 to 0.14 in a theta solvent as the grafting density increases from 0.51 to 1.94 chains nm–2. This new definition of λ can also predict the effective radii of nanopa...

Manipulation of crystalline structures of conjugated polymers (CPs) within nanostructured block copolymer (BCP) domains is crucial to enhance their electrical properties. However, this has been a challenge due to the intrinsic incompatibility between crystallization and phase-separation process of CP-based BCPs, which often causes break-out crystallization and results in disordered nanostructures and poor electrical properties. Herein, we demonstrate solvo-microwave annealing as an effective method for producing thin film structures of CP-based BCPs with well-ordered nanostructures and high crystallinity in a very short processing time (∼3 min). This approach is applied for poly(3-dodecylthiophene)-block-poly(lactic acid) (P3DDT-b-PLA) copolymers as a model system, where the PLA block offers the additional benefit of selective etchability to provide an on-chip etch mask for pattern transfer. The conventional thermal annealing process, even with a long annealing time (∼24 h), resulted in incompatibility between ordered nanostructures and the crystallization of the conjugated polymer. In contrast, the solvo-microwave annealing with a combination of heat and solvent vapor treatment was employed to grant enhanced chain mobility and solvent interaction with the π–π structure of the conjugated polymer. As a result, this process rapidly generated nanostructures with very few defects within 3 min and, at the same time, the highly crystalline intermolecular ordering of the P3DDT blocks occurred. Furthermore, we demonstrate the successful transfer of highly-ordered P3DDT structures after the removal of the PLA domain, which is important for potential applications in nanolithography and electronics.

Herein, we report the development of poly(3-hexylthiophene) regioblock copolymers (block-P3HTs), which are composed entirely of identical 3-hexylthiophene repeating units, with one block being highly regioregular (rre) and the second block being regiorandom (rra). This block-P3HT was prepared via catalyst-transfer polycondensation by the sequential addition of different monomer batches, with 3-hexylthiophene (3HT) monomers used for the rre block and a mixture of 3HT and 3,3′-dihexyl-2,2′-bithiophene (BT) monomers for the rra block. The average regioregularity (RRavg) of the block-P3HTs was tuned from 58 to 79% by differentiating the weight ratio between the rre and rra blocks, and the crystalline behavior of block-P3HTs in comparison with polymers having similar RRavg but a random distribution of 3HT and BT units (co-P3HT) was investigated. This study allowed for the exploration of the effects of the distribution of regiodefects within the polymer chain (e.g. confined to a single block versus uniformly distributed throughout the polymer) on the crystalline behaviors of the polymer. For example, block-P3HT with 72% RRavg formed long nanowires by solution assembly, due to the strong crystallinity from a sufficient effective conjugation length in the rre block, whereas co-P3HT with the same RRavg formed spherical micelles indicating amorphous characteristics. Overall, the block-P3HTs showed a strong tendency to crystallize, even with very low RRavg, driven by the rre block in the polymers, whereas the crystallinity of the co-P3HTs was substantially suppressed due to chain distortion by the distributed regiodefects.

Cell migration plays an important role in the identification of various diseases and physiological phenomena in living organisms, such as cancer metastasis, nerve development, immune function, wound healing, and embryo formulation and development. The study of cell migration with a real-time microscope generally takes several hours and involves analysis of the movement characteristics by tracking the positions of cells at each time interval in the images of the observed cells. Morphological analysis considers the shapes of the cells, and a phase contrast microscope is used to observe the shape clearly. Therefore, we developed a segmentation and tracking method to perform a kinetic analysis by considering the morphological transformation of cells. The main features of the algorithm are noise reduction using a block-matching 3D filtering method, k-means clustering to mitigate the halo signal that interferes with cell segmentation, and the detection of cell boundaries via active contours, which is an excellent way to detect boundaries. The reliability of the algorithm developed in this study was verified using a comparison with the manual tracking results. In addition, the segmentation results were compared to our method with unsupervised state-of-the-art methods to verify the proposed segmentation process. As a result of the study, the proposed method had a lower error of less than 40% compared to the conventional active contour method.

Conjugated block copolymers (BCPs) can self-assemble into highly ordered nanostructures in a melt state. However, when cooled below the melting temperature, crystal growth can disrupt the self-assembled structure and produce a poorly ordered fibrillar texture. We demonstrate that crystallization modes of conjugated BCPs based on poly(3-dodecylthiophene) (P3DDT) and poly(2-vinylpyridine) (P2VP) can be tuned through P3DDT regioregularity (RR), as this attribute controls the melting temperature and crystallization rates of P3DDT. When RR is low (70–80%), crystallization is observed at temperatures near or below the glass transition of P2VP, so crystal growth is largely confined by the glassy cylindrical or lamellar BCP structure. When RR is high (94%), crystallization occurs at 40 K above the glass transition of P2VP, so there is no longer a restriction of glassy domains. Importantly, crystal growth remains confined by the rubbery P2VP lamellae, but breaks through the rubbery P2VP cylinders. This morphology-...

Microphase-separation behavior of conjugated–amorphous block copolymers (BCPs) is driven by a complex interplay between Flory–Huggins interaction (χ), liquid crystalline (LC) interaction, and crystallization. Herein, in order to elucidate the influence of LC interaction on the morphology of the BCPs, we report the effects of regioregularity (RR) on the microphase separation and molecular packing structures of poly(3-dodecylthiophene)-block-poly(2-vinylpyridine) (P3DDT-b-P2VP). To decouple the effect of LC interactions from crystallization kinetics, we investigate the morphological behavior of the P3DDT-b-P2VP at above the melting temperature of P3DDT (∼160 °C). Both electron microscopy and X-ray scattering show an abrupt reduction in the domain spacing of both lamellar and cylindrical phases as the RR of P3DDT block increases. Specifically, lower RR (i.e., 85, 79, and 70%) BCPs have larger domain spacings than high RR (94%) by 50% (lamellar) or 80% (cylindrical), even though the overall molecular weights ...

Development of particles that change shape in response to external stimuli has been a long-thought goal for producing bioinspired, smart materials. Herein, the temperature-driven transformation of the shape and morphology of polymer particles composed of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers (BCPs) and temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) surfactants is reported. PNIPAM acts as a temperature-responsive surfactant with two important roles. First, PNIPAM stabilizes oil-in-water droplets as a P4VP-selective surfactant, creating a nearly neutral interface between the PS and P4VP domains together with cetyltrimethylammonium bromide, a PS-selective surfactant, to form anisotropic PS-b-P4VP particles (i.e., convex lenses and ellipsoids). More importantly, the temperature-directed positioning of PNIPAM depending on its solubility determines the overall particle shape. Ellipsoidal particles are produced above the critical temperature, whereas convex lens-shaped particles are obtained below the critical temperature. Interestingly, given that the temperature at which particle shape change occurs depends solely on the lower critical solution temperature (LCST) of the polymer surfactants, facile tuning of the transition temperature is realized by employing other PNIPAM derivatives with different LCSTs. Furthermore, reversible transformations between different shapes of PS-b-P4VP particles are successfully demonstrated using a solvent-adsorption annealing with chloroform, suggesting great promise of these particles for sensing, smart coating, and drug delivery applications.