33 research outputs found

    STRUCTURAL COLOR COATING FILMS COMPOSED OF AN AMORPHOUS ARRAY OF SILICA AND CARBON BLACK PARTICLES BY ELECTROPHORETIC DEPOSITION

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    The color of a dye or pigment is an inherent property of the material that depends on its chemical nature. Some of these paints, especially those containing organic dye molecules, easily fade over time or upon exposure to light. In addition, there is concern over unfavorable influences on health and the environment, as some paints contain harmful substances. Therefore, coloration free from photo-bleaching or toxic materials is a central goal of paint research. Structural color is one of the most promising candidates to solve this challenge [1]. Submicron-sized microstructures reflect or scatter light so that waves of certain frequencies can constructively interfere to form this type of color. Because electronic excitation is not involved in the coloration mechanism, the structural color is not susceptible to fading unless the microstructure is destroyed. Structural color from particle arrays is advantageous in the sense that the color can be tuned merely by choosing the size of the microstructure without changing the material design. However, structural color from crystalline array of particles typically exhibits angular dependence, which is unfavorable for general purposes. Commonly used paints ideally appear the same color regardless of the viewing angle. In this study, we describe a novel and simple procedure to create a low angular dependence structural color coating by the electrophoretic deposition (EPD) process using SiO2 particles. A homogeneous coating film composed of an amorphous array of SiO2 particles was obtained by the EPD. However, the structural colors emitted from these arrays are very pale because the incoherent light scattering across the entire visible region is very strong. To reduce the contribution of incoherently scattered light to the overall scattering spectrum and to enhance the structural color of the colloidal amorphous arrays, black components, which absorb light uniformly across the entire visible region, can be incorporated into the films. Carbon black (CB) is one of the most common and environmentally preferable black substances and reflects very little light in the visible region of the spectrum. Sufficient visibility of the structural color was achieved by the co-deposition of carbon CB. The thickness of the coating films can be controlled by varying the applied voltage and/or deposition time. When the EPD process is carried out with a low applied voltage, a close-packed array of SiO2 particles that exhibits an iridescent structural color is obtained (Figure1a). However, an amorphous packing state can be acquired at a high applied voltage condition (Figure1b). The structural color generated from such coating films has a low angle dependence. These results indicate that the arrangement of particles in the array and the iridescence of the resultant structural color can also be controlled by varying the EPD conditions. Various vividly colored coatings can be produced from SiO2 particles with diameters between 200 and 300 nm. Moreover, coatings on materials with curved surfaces and complicated shapes, which are difficult to obtain by commonly used techniques were also successfully prepared via the EPD process. Please click Additional Files below to see the full abstract

    Controlled Multistructural Color of a Gel Membrane

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    Functional polymethacrylate composite elastomer filled with multilayer graphene and silica particles

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    In this work, a three-component composite elastomer consisting of poly(di(ethylene glycol)methyl ether methacrylate) (PMEO2MA), 110 nm spherical silica particles and multilayer graphene (MLG) is fabricated and its various functions brought about by the characteristic morphology formed by silica particles and MLG are clarified. The presence of silica particles greatly improved the dispersibility of MLG in PMEO2MA, allowing more MLG to be filled. The relative dielectric constant (ε) of the composite elastomers can be increased by increasing the amount of MLG while suppressing the increase in dielectric loss tangent (tanδ). The thermal conductivity of the composite elastomer peak in the middle of the increase in MLGs when the silica particles are not filled, whereas the silica particle-filled system is able to fill the MLGs up to a higher volume fraction and shows higher thermal conductivity. The dynamic viscoelasticity analysis of the composite elastomers shows that the filling effect of MLG is more remarkable in the composite elastomer containing 40 vol% silica particles. The loss factor of vibration damping is found to be larger in the 40 vol% SiO2 - 2.8 vol% MLG composite elastomer over a wider frequency range than in the non-MLG samples

    Template Synthesis of Poly( N

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    Synthesis of thermo-responsive polymer gels composed of star-shaped block copolymers by copper-catalyzed living radical polymerization and click reaction

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    ABSTRACTIn recent times, there has been a significant surge in research interest surrounding thermo-responsive water-soluble polyacrylamides, primarily due to their intriguing capability to undergo significant solubility changes in water. These polymers exhibit the remarkable ability to shift from a soluble to an insoluble state in response to temperature variations. The capacity of these polymers to dynamically respond to temperature changes opens up exciting avenues for designing smart materials with tunable properties, amplifying their utility across a spectrum of scientific and technological applications. Researchers have been particularly captivated by the potential applications of thermo-responsive water-soluble polyacrylamides in diverse fields such as drug delivery, gene carriers, tissue engineering, sensors, catalysis, and chromatography separation. This study reports the construction and functionalization of polymer gels consisting of a polymer network of polyacrylamide derivatives with nano-sized structural units. Specifically, thermo-responsive polymer gels were synthesized by combining well-defined star-shaped polymers composed of polyacrylamide derivatives with a multifunctional initiator and linking method through a self-accelerating click reaction. The polymerization system employed a highly living approach, resulting in polymer chains characterized by narrow molecular weight distributions. The method’s high functionality facilitated the synthesis of a temperature-responsive block copolymer gel composed of N-isopropyl acrylamide (NIPA) and N-ethyl acrylamide (NEAA). The resulting polymer gel, comprising star-shaped block copolymers of NIPA and NEAA, showcases smooth volume changes with temperature jumps

    Controlling the dynamics of elastomer networks with multivalent brush architectures

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    A method for lowering the activation energy of melting while improving the mechanical robustness of an elastomer was achieved using bottlebrush topologies. This system has the potential to realize self-healing materials with enhanced processability.</jats:p
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