Chitosan-<i>grafted</i>-Gallic Acid as a Nature-Inspired Multifunctional Binder for High-Performance Silicon Anodes in Lithium-Ion Batteries

Due to its high theoretical specific capacity and natural abundance, silicon (Si) and its composites are considered to be pivotal anode materials for high-energy-density next-generation lithium-ion batteries (LIBs). However, the significant volume changes during the repeated lithiation/delithiation process cause the loss of electrical contact and the continuous formation of a solid electrolyte interface (SEI), hindering Si’s practical applications. The rational design of the polymer binder is an efficient approach to preserve the electrode’s structure from large Si volume changes, thereby enhancing the cycle performance in lithium-ion batteries. We developed an aqueous binder using a plant-inspired adhesive phenolic moiety, gallic acid (3,4,5-trihydroxybenzoic acid, GA), grafted onto the marine-based polymer, chitosan (CS) by a simple radical reaction. The chitosan-grafted-gallic acid, CS-g-GA, not only improves the water solubility of CS but also achieves enhanced binding properties onto Si, hence contributing to better accommodating the volume expansion of Si during the repeated cycling and also maintaining the structural integrity of the Si electrode electronic made from the CS-g-GA as a binder. Si@CS-GA-100 exhibits excellent high-rate capability and long cycling stability, delivering a high reversible specific capacity of 1868 mAh g–1 with a capacity retention of 67% at a rate of 0.5 C after 350 cycles

Biphenyl(isatin<i>-co-</i>trifluoroacetophenone)-Based Copolymers Synthesized Using the Friedel–Crafts Reaction as Mechanically Robust Membranes for Efficient CO₂ Separation

In this study, we report a series of ether bond-free (i.e., full carbon backbone) copolymers, prepared for the first time by a simple one-step Friedel–Crafts (F–C) polycondensation reaction using biphenyl-isatin (BP-Isa), a torsion-resistant rigid segment with high CO2 selectivity, and biphenyl-trifluoroacetophenone (BP-TFAPh), a highly permeable ladder-type segment. The copolymer exhibits a high molecular weight, moderate BET surface area, and excellent thermophysical properties. (BP-Isa)x-(BP-TFAPh)y copolymers containing over 50% TFAPh loading show a perfect combination of mechanical properties and gas separation properties, outperforming most commercial gas separation polymers, most F-C polymers, and high-performance PIM-PI-1 polymer membranes. (BP-Isa)x-(BP-TFAPh)y copolymer membranes with loadings over 50% also exhibited a good CO2 permeability of 394–526 Barrer and good CO2/N2 and CO2/CH4 selectivities of 24.4–29.0 and 19–25, respectively. Also, the 50:50 composition of the copolymer films exhibited excellent antiaging properties for up to one month, with good resistance to plasticization at pressures of up to 15 atm

Effect of the cyclic uniaxial stretch on the orientation of PDL cells.

<p>Examination of cell shaping on the differently-aligned nanofibers with or without applying dynamic mechanical load. F-actins visualized with rhodamine-phalloidin (red) and nuclei stained with DAPI (cyan) for fluorescent images. Red arrows indicate stretch direction.</p

Schematic of experimental design.

<p>Mechanical-stressed PDL cells supported on nanotopological-cued nanofiber membrane scaffolds. The Flexcell system equipped with the PDL cells supported on nanofiber matrix, where the dynamic mechanical tensional force was applied to the matrix/cell through equipment vacuum.</p

Expressions of proteins related with ligamentogenesis of the PDL cells, as analyzed by an ELISA.

<p>(a) Periostin, (b) tenascin, and (c) TGF-β. Results presented when normalized to the static condition with random nanofiber. (^a<i>p</i> < 0.05 compared to DA, ^b<i>p</i> < 0.05 compared to SA, by ANOVA).</p

Illustrative images showing the PDL defect models used in this study.

<p>(a) Photograph of rat premaxillary operation field. Note the dimensions of the defect used to produce standardized 4 mm diameters round full-thickness defects on the lateral surface of premaxilla bone. Two defects were created on one animal and were covered with tissue-engineered construct. (b) Harvested specimens of rat premaxillary operation field after sacrifice. (c) Representative histology image of HE staining of new bone tissue formed within the defect at 4 weeks (black arrow: defect margins) (Magnification x40, scale bar 500 μm). (d) 2D and (e) 3D μCT images. The original outline of the 4 mm defect is clear (white arrow).</p

HE stained histological images, showing the tissue regeneration in the periodontal defect model.

<p>(Magnification x400, scale bar 100 μm, NB: new bone, OB: old bone, TEM: tissue-e engineered matrix, RCT: reconstructed connective tissue).</p

The orientation of and protrusion behaviors of the cells.

<p>Analyses of the PDL cell orientation and cytoskeletal protrusion, after cell culture under the influence of nanofiber alignment and/or cyclic mechanical load. (a) Distribution of cell orientation angles. (b) Number of cytoskeletal protrusions, and the (c) distribution of protrusion length and (d) average protrusion length. Only bipolar cells were also analyzed in terms of distribution of (e) orientation angle and (f) protrusion length. (^a<i>p</i> < 0.05 compared to DA, by ANOVA).</p

Micro-CT image analyses results of bone regeneration.

<p>(a) % bone volume (b) bone surface, and (c) bone surface density. The graph represented statistically significant differences among the study groups on the quantification of new bone formation in premaxillary defects after 4 weeks of healing. (^a<i>p</i> < 0.05 compared to DA (remov); ^b<i>p</i> < 0.05 compared to SA (remov); ^c<i>p</i> < 0.05 compared to DA (sound), by ANOVA).</p

Tissue compatibility of the PDL cell/nanofiber constructs implanted in rat subcutaneous model for 4 weeks.

<p>Histological images of HE and MT stains. Notable observation of PDL-like tissues with spindle-shaped oriented cells in the SA and DA groups, as revealed by MT stain. Direction of the PDL cells (two headed arrow) with randomly distributed collagen fibers were marked (Magnification x400, scale bar 100 μm).</p