Conventionally, low‐surface‐tension fluorinated reagents are incorporated into anti‐smudge (oil‐ and water‐repellent) coatings for oil repellency. However, fluorinated compounds are expensive and an ...environmental concern because of their high stability and bioaccumulation. These factors limit their widespread application. We report herein the development of fluorine‐free anti‐smudge polyurethane coatings that are clear at thicknesses up to tens of micrometers and are able to sustain extensive surface damage. We demonstrate that these coatings can be applied readily onto a diverse range of substrates.
Wear and tear without a smear: Anti‐smudge polyurethane coatings produced without fluorinated reagents were clear at thicknesses up to tens of micrometers. The coatings were applied to a diverse range of substrates and shown to repel ink, a fingerprint liquid, paint, and water. Moreover, they retained their anti‐smudge properties even after extensive wear.
Polyurethane coatings containing nanopools of a grafted lubricating liquid ingredient for dewetting enablement (NP-GLIDE) are prepared by curing a commercial polyol P0, a hexamethylene diisocyanate ...trimer, and P1-g-PDMS, which is a graft copolymer consisting of a polyol backbone P1 bearing poly(dimethylsiloxane) (PDMS) side chains. These materials are known as NP-GLIDE because most test liquids have no problem to cleanly glide off them and because segregated nanopools of the grafted lubricating ingredient (PDMS) for dewetting enablement are dispersed throughout the coating matrix. To optimize the dewetting performance of the NP-GLIDE coatings, the molecular weights of the PDMS side chains in the P1-g-PDMS samples were increased from 1.0 kDa (1k) to 5.0 kDa (5k) and 10.0 kDa (10k). A comparative study of the coatings containing three different P1-g-PDMS samples at a constant PDMS mass fraction of either 6.0 or 2.00% (m/m) showed that P1-g-PDMS5k-based coatings exhibited the best dewetting properties. These properties included the lowest sliding angles for test liquids that were incompatible with PDMS and the fastest and most effective contraction of marker ink traces and a paint. Coatings containing 0.50 and 1.00% (m/m) of PDMS5k were also prepared from P1-g-PDMS5k and compared with those containing 2.00 and 6.0% (m/m) of PDMS5k. The coatings were shown to retain their dewetting properties with the PDMS contents as low as 1.00% (m/m). Although the results of this study provided valuable insight into the design of future practical NP-GLIDE coatings, a model has also been proposed for the surface structure of the coatings to justify our observations.
The combination of the inherently complex structure of ABC triblock terpolymers with careful selection of the assembly conditions can yield an incredible array of nanostructures in solution. In this ...review we will highlight recent progress in the self-assembly of triblock terpolymers in solution. We will discuss various approaches that are available to tune triblock terpolymer assembly. These approaches include changing the block sequence, the block ratios, adjusting the solvent conditions, incorporating stimuli-responsive or crystalline blocks, and employing complexation agents. Triblock terpolymer self-assembly in solution has so far produced core–shell–corona systems, multicompartmental micelles, Janus systems, helices, micelles with segregated coronas, and numerous other systems.
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Reported are the preparation and application of a triblock terpolymer poly(ethylene oxide)-ONB-poly2-(perfluorooctyl)ethyl methacrylate-block-poly(2-cinnamoyloxyethyl methacrylate) ...(PEO-ONB-PFOEMA-b-PCEMA). Here PEO is water-soluble, PCEMA is photo-cross-linkable, PFOEMA is of low surface tension, and ONB denotes a photocleavable o-nitrobenzyl unit at the junction of the PEO and PFOEMA blocks. To prepare the copolymer, a macroinitiator bearing an ONB unit between PEO and the initiating site was first synthesized. FOEMA and 2-trimethylsilyloxyethyl methacrylate (HEMA-TMS) were then sequentially polymerized by atom transfer radical polymerization (ATRP) to yield the triblock copolymer PEO-ONB-PFOEMA-b-P(HEMA-TMS). Removal of the trimethylsilyl groups from the P(HEMA-TMS) block and cinnamation of the resultant poly(2-hydroxyethyl methacrylate) block with cinnamoyl chloride resulted in the targeted triblock copolymer. PEO-ONB-PFOEMA-b-PCEMA formed micelles in tetrahydrofuran/water at the water volume fraction of 80%, in which only the PEO block was soluble. Upon photolysis, the micellar PCEMA cores were cross-linked and the micellar coronal PEO chains were cleft, resulting in the precipitation of cross-linked PFOEMA-b-PCEMA nanoparticles. Films of the nanoparticles were water- and oil-repellent due to the exposure of the initially hidden PFOEMA block.
Despite the diversity of nanostructures that have been created from block copolymers over the past two decades, the challenging fabrication of polymer nanocapsules bearing regularly sized ...nanochannels has not been possible until now. In this study, a pseudo miktoarm copolymer μ-(PtBA)(PCEMA)(PEO)1.14 was prepared. The copolymer consisted of 1 poly(tert-butyl acrylate) (PtBA) chain, 1 poly(2-cinnamoyloxyethyl methacrylate) (PCEMA) chain, and an average 1.14 poly(ethylene oxide) (PEO) chains. This polymer formed vesicles in a tetrahydrofuran/water solvent mixture with the soluble PEO block as the corona. At 100 units long, the PtBA chains formed cylinders that permeated the wall made of PCEMA chains at 130 units long. Photo-cross-linking the PCEMA wall and hydrolyzing the PtBA chains in the cylindrical domains yielded unprecedented capsules bearing regularly packed uniform poly(acrylic acid)-gated nanochannels. These capsules exhibited pH-responsive reagent release in aqueous media.
Stroke affects millions each year. Poststroke brain edema predicts the severity of eventual stroke damage, yet our concept of how edema develops is incomplete and treatment options remain limited. In ...early stages, fluid accumulation occurs owing to a net gain of ions, widely thought to enter from the vascular compartment. Here, we used magnetic resonance imaging, radiolabeled tracers, and multiphoton imaging in rodents to show instead that cerebrospinal fluid surrounding the brain enters the tissue within minutes of an ischemic insult along perivascular flow channels. This process was initiated by ischemic spreading depolarizations along with subsequent vasoconstriction, which in turn enlarged the perivascular spaces and doubled glymphatic inflow speeds. Thus, our understanding of poststroke edema needs to be revised, and these findings could provide a conceptual basis for development of alternative treatment strategies.
Two linear triblock terpolymers were synthesized and used to coat cotton textiles. These copolymers consist in sequence of a water-soluble poly(ethylene glycol) (PEG) block, a highly water- and ...oil-repellant poly2-(perfluorooctyl)ethyl methacrylate (PFOEMA) block, and a photo-cross-linkable poly(2-cinnamoyloxyethyl methacrylate) (PCEMA) block. The PEG block bonds to PFOEMA via a redox-cleavable disulfide junction (-S 2-). To prepare the copolymers, monomethoxy PEG (PEG-OH) was derivatized to yield a PEG chain bearing one terminal thiol group (PEG-SH). Atom transfer radical polymerization and deprotection chemistry were used to prepare Py-S 2-PFOEMA-b-PHEMA, where PHEMA and Py-S 2- denote poly(2-hydroxyethyl methacrylate) and a terminal pyridin-2-yldisulfanyl group, respectively. Reacting PEG-SH with Py-S 2-PFOEMA-b-PHEMA via a thiol–disulfide exchange reaction yielded PEG-S 2-PFOEMA-b-PHEMA, and the cinnamation of the PHEMA block produced PEG-S 2-PFOEMA-b-PCEMA. PEG-S 2-PFOEMA-b-PCEMA dispersed in water and plasticized by a trace amount of dimethyl phthalate was then used to coat cotton textiles, and this coating was secured by photo-cross-linking the PCEMA domains. Treating the coating with dithiothreitol cleft the disulfide junction and thus the PEG block, revealing the hidden PFOEMA block and its water- and oil-repellant properties. Aqueous solutions of these copolymers could thus be applied onto a substrate to provide amphiphobic coatings.
Density peaks clustering (DPC) is a density-based clustering algorithm with excellent clustering performance including accuracy, automatically detecting the number of clusters, and identifying center ...points. However, the local density of DPC strongly depends on the cutoff distance which must be prespecified; in addition, the strategy assigns each remaining point to the same cluster as its nearest neighbor of higher density in descending order of local density, which is likely to cause cluster label error propagation. To overcome these limitations, we propose an improved DPC by introducing weighted local density sequence and two-stage assignment strategies, called DPCSA. Many previous improved DPC algorithms neglect additional complexity, whereas DPCSA incorporates the nearest neighbor dynamic table to enhance clustering efficiency. The experimental results for 12 artificial and 11 real-world datasets, including Olivetti face, verify that the DPCSA clustering performance is significantly superior to DPC and DPC via heat diffusion (HDDPC), and slightly superior to fuzzy weighted k-nearest neighbors density peak clustering (FKNNDPC). In addition, the DPCSA is more computationally efficient than FKNNDPC and HDDPC, but less than DPC. The source code of DPCSA is available at https://www.github.com/Yu123456/DPCSA .
The 6-UCU (U-universal joint; C-cylinder joint) kind Gough-Stewart platform is extensively employed in motion simulators due to its high accuracy, large payload, and high-speed capability. However, ...because of the manufacturing and assembling errors, the real geometry may be different from the nominal one. In the design process of the high-accuracy Gough-Stewart platform, one needs to consider these errors. The purpose of this paper is to propose an optimal design method for the 6-UCU kind Gough-Stewart platform with a guaranteed given accuracy. Accuracy analysis of the 6-UCU kind Gough-Stewart platform is presented by considering the limb length errors and joint position errors. An optimal design method is proposed by using a multi-objective evolutionary algorithm, the non-dominated sorting genetic algorithm II (NSGA-II). A set of Pareto-optimal parameters was found by applying the proposed optimal design method. An engineering design case was studied to verify the effectiveness of the proposed method.
Metabolic reprogramming is a hallmark of cancers, but pan-cancer level roles of lipid metabolism in cancer development are remains poorly understood. We investigated the possible roles of lipid ...metabolic genes (LMGs) in 14 cancer types. The results indicate that: (1) there is strong evidence for increased lipid metabolism in THCA and KICH. (2) Although the overall levels of lipid metabolic processes are down-regulated in some cancer types, fatty acid synthase activity and fatty acid elongation are moderately up-regulated in more than half of the cancer types. Cholesterol synthesis is up-regulated in five cancers including KICH, BLCA, COAD, BRCA, UCEC, and THCA. (3) The catabolism of cholesterols, triglycerides and fatty acids is repressed in most cancers, but a specific form of lipid degradation, lipophagy, is activated in THCA and KICH. (4) Lipid storage is enhanced in in kidney cancers and thyroid cancer. (5) Similarly to primary tumors, metastatic tumors tend to up-regulate biosynthetic processes of diverse lipids, but down-regulate lipid catabolic processes, except lipophagy. (6) The frequently mutated lipid metabolic genes are not key LMGs. (7) We established a LMG-based model for predicting cancer prognosis. Our results are helpful in expanding our understanding of the role of lipid metabolism in cancer.
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