A new member of low‐dimensional structures with a high aspect ratio (LDHA) is introduced. For the first time, commodity polymer is processed into LDHA, which has long been stagnated by the lack of suitable processing techniques. The key to solve the current bottleneck is to overcome the trade‐off between kinetic processability and thermodynamic stability. These two factors are both highly determined by intermolecular interaction level (IIL). Thus with a wide tuning range of IIL, ultrahigh molecular weight polyethylene (UHMWPE) is selected and investigated to break through the trade‐off. Polymeric LDHA preparation needs both thinning and stiffening. By focusing on one then the other sequentially, they are realized simultaneously. Thus the over sixty‐year‐old material is finally thinned down by seven orders of magnitude into a 65.5 nm thick and 0.64 m2 large lamellar‐thin framework (LTF). LTF exhibits a series of exceptional properties such as over‐95% transparency, and seven times higher specific strength referred to steel. For the first time, cryogenic electron microscopy (Cryo‐EM) is utilized to observe commodity polymers directly. This new LDHA material is promising to expand the scale boundaries of both fundamental research and practical applications, not only for UHMWPE, but also for more commodity polymers to come.
Lamellar Frameworks In article number 2107941, Runlai Li, Qiang Fu, and co‐workers propose a method to thin down commodity polymers into lamellar thin frameworks (LTF) with a square‐meter large area. Interactions between molecules are regulated by multistep processing for ordered molecular alignment. The prepared new structures (LTF and shish‐network), properties (ultrahigh transparency and specific stiffness), and measurements may promote fundamental research and novel practical applications of commodity polymers.
For the first time, an ultrathin type of ultra‐high molecular weight polyethylene (UHMWPE) membrane of only 350 nm thickness is surface modified by direct fluorination and plasma treatments. Then a notable suppression in crystallinity is observed. A total of four kinds of thickness, from 350 nm to 6 µm, are investigated to correlate the modification effect on the thickness. Microscopically, the continuous shish‐kebab structure transforms into scattered lamellae clusters. And the damage to the surface morphologies increases as the thickness decreases, yet the resultant contact angles remain almost constant. Especially for the 350 nm thin UHMWPE, the mildest fluorination treatment slightly changes the contact angle, while the multiscale structure changes significantly from crystalline to mesoscopic level. As thickness decreases from 6 µm to 350 nm, the modified volume ratio of membranes increases, and the volumetric modification is almost realized for the 350 nm membrane.
Methane, as the transitional fuel, still emits CO2 during combustion but less than gasoline. Developing new adsorption materials can improve the efficiency of methane storage and then achieve the goal safely and economically. Metal-organic Frameworks (MOF) with the advantage of high porosity and adjustable pore surface area, are considered one of the promising materials for natural storage. Here, this article briefly introduces the preparation of MOF and mentions some details during this process such as the solvothermal technique, and electrochemical synthesis methods, covering some defects in the preparation process. Many kinds of materials have different volumetric adsorption rates and mass adsorption rates compared with DOE standards. In chronological order, this paper lists some typical materials and discusses specific structures inside MOFs corresponding to relative performance. Changing or adjusting organic ligands can improve capacities so that a series of MOFs are designed like MFM-132, MFM-112 and MFM-115. In addition, the factors influencing adsorption rate are also considered including internal factors, surface area, porosity, structure, adsorption isotherm and external factors, pressure, and temperature, respectively
Droplet-induced electricity generation, as one of the most emerging environmental energy harvesting technologies, has been extensively investigated for nearly a decade. Its interaction between ions (in droplets), electrons (in conductors, e.g. graphene), and charges (on the substrate surface) is the key to electricity generation. However, the indirect interaction between ions and charges due to the shielding effect from conductors, inevitably suppresses device performance and limits conductor selection. Here, we addressed above issues by proposing an out-of-plane electrokinetic effect based on a 100 nm-thick negatively charged polyethylene nanomembrane, providing direct interactions between ions and charges, with the shielding effect of conductors eliminated. This new paradigm of electrokinetics could induce a persistent potential for 6 hours (first enduring DEG) and a specific power of 177.2 nW/µL (highest droplet-induced electrokinetics). With new device topologies and extensive conductor materials unlocked, this work is expected to elucidate more physical picture of electrokinetics.
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