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Programmable Fabrication of Submicrometer Bent Pillar Structures Enabled by a Photoreconfigurable Azopolymer
摘要： Anisotropic small structures found throughout living nature have unique functionalities as seen by Gecko lizards. Here, we present a simple yet programmable method for fabricating anisotropic, sub-micron-sized bent pillar structures using photo-reconfiguration of an azopolymer. Slant irradiation of a p-polarized light on the pillar structure of an azopolymer simply results in a bent pillar structure. By combining the field-gradient effect and directionality of photo-fluidization, control of the bending shape and the curvature is achieved. With the bent pillar patterned surface, anisotropic wetting and directional adhesion are demonstrated. Moreover, the bent pillar structures can be transferred to other polymers, highlighting the practical importance of this method. We believe that this pragmatic method to fabricate bent pillars can be used in a reliable manner for many applications requiring the systematic variation of a bent pillar structure.
关键词： azopolymer,photo-reconfiguration,directional dry adhesive,bent pillar,anisotropic wetting
更新于2025-09-11 14:15:04
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Effects of laser-textured surface pattern on the wetting behavior and composition optimization of brazing filler: experimental study and numerical simulation
摘要： To reduce interface brittle compounds of brazed joints, laser-textured surface pattern was used instead of excessive active element to enhance the wetting behavior of brazing filler on Ti3SiC2 ceramic substrate. The cylindrical surface pattern was designed by theoretical calculation and examined by numerical simulation. The numerical simulation results showed that the cylindrical surface pattern can not only effectively reduce the wetting angle on the substrate surface, but also greatly accelerate the spreading process of brazing filler. The results of wetting experiment showed that the wettability of Ag–Cu–2Ti (wt.%) brazing filler on Ti3SiC2 with cylindrical surface pattern sufficiently increased compared with that on smooth surface, which were consistent with the theoretical calculation and numerical simulation results. The titanium content in Ag–Cu–Ti that suitable for the brazing of Ti3SiC2 even could be reduced from 4.5 to 2.0 wt.%. The novel method provides a feasible route for promoting the wetting behavior and achieving composition optimization of brazing filler.
关键词： Ceramics,Wetting,Composition optimization,Surface pattern
更新于2025-09-11 14:15:04
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Advantages of the Surface Structuration of KBr Materials for Spectrometry and Sensors
摘要： A potassium bromide (KBr) material, which has been widely used as the key element in Fourier spectrometers and as the output window of the IR-lasers, was studied via applying carbon nanotubes in order to modify the potassium bromide surface. The laser-oriented deposition method was used to place the carbon nanotubes at the matrix material surface in the vertical position at different electric ?elds varying from 100 to 600 V × cm?1. The main idea of the improvement of the spectral properties of the potassium bromide structure is connected with the fact that the refractive index of the carbon nanotubes is substantially less than the refractive index of the studied material, and the small diameter of the carbon nanotubes allows one to embed these nano-objects in the voids of the lattice of the model matrix systems. Moreover, the mechanical characteristics and wetting features of potassium bromide structures have been investigated under the condition mentioned above. Analytical and quantum-chemical simulations have supported the experimental results.
关键词： surface structuration,potassium bromide,mechanical and wetting properties,laser-oriented deposition method,carbon nanotubes,spectra
更新于2025-09-10 09:29:36
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Durable, Optically Transparent, Superhydrophobic Polymer Films
摘要： Transparent and superhydrophobic free-standing films would be useful for extending non-wetting properties to optical applications especially those exposed to flowing water. However two challenges, transparency and durability, have proven difficult to overcome. Although a high degree of surface roughness is essential to sustain droplets of water in the Cassie state, this same roughness can lead to significant scattering and loss of optical clarity. Reducing roughness to a length scale below ? the wavelength of light reduces scattering, but can result in loss of durability. In this paper we describe a novel and simple lamination approach for treating free-standing films to become superhydrophobic, with high transparency and durability, by partially embedding hydrophobic silica nanoparticles into the surface of a cyclic olefin polymer (COP) film. Partial embedding insures that the particles are firmly adhered while their nano-scale roughness is exposed, resulting in excellent superhydrophobicity (contact angles >160° and roll off angle <10°), high transparency (over 87% transmission at 500 nm) and durability under flowing water (>6 hours at volumetric flow rate of 70 liters·min-1). The effect of processing parameters including the particle coating thickness and lamination conditions on the optical properties, hydrophobicity as well as mechanical durability of films are systematically studied.
关键词： wetting,optical transmittance,surface morphology,Superhydrophobicity,durability,lamination
更新于2025-09-10 09:29:36
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Lithography-induced hydrophobic surfaces of silicon wafers with excellent anisotropic wetting properties
摘要： In recent years, hydrophobic surfaces have attracted more and more attentions from many researchers. In this paper, we comprehensively discussed the effects of specific parameters of microstructures on the wetting properties by using the theoretical models, the effects of microstructures on two-dimensional anisotropic properties and the water droplet impact experiment. Firstly, the relationships between the CAs and variable parameters were explored after the formula derivation for three various patterns. Then three different patterns were fabricated successfully on the silicon wafers by lithography technology and the effects of microstructures (including LWD parameters and interval parameters) on surface wettability were studied based on the theoretical research. After that, the effects of microstructures on two-dimensional anisotropic properties were also studied. Finally, the water droplet impact experiment was carried out and the viscoelastic properties were simply investigated. Our research proposed a potential method for fabricating hydrophobic surfaces with excellent anisotropic properties. This method may be widely used in a variety of academic and industrial applications in the future.
关键词： lithography technology,theoretical models,anisotropic wetting,silicon wafers,hydrophobic surfaces
更新于2025-09-09 09:28:46
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Effect of Ti addition on the wetting and brazing of Sn0.3Ag0.7Cu filler on SiC ceramic
摘要： The wetting behavior of Sn0.3Ag0.7Cu (SAC) filler with the addition of Ti on SiC ceramic was investigated using sessile drop method. SiC/SiC was brazed by SAC-Ti filler with different Ti content at 1223 K (950 °C) for 10 minutes. The wettability of SAC-Ti filler on SiC was significantly enhanced with the addition of Ti. The contact angle decreased at first and then increased with increasing Ti content. The lowest contact angle of 9° was obtained with SAC-1.5Ti (wt.%) filler. When Ti content further increased to 2.0 wt.%, the contact angle increased, due to the intense reaction of Ti-Sn. The reaction between Ti and SiC controlled the wetting behavior of SAC-Ti on the SiC substrate and the reaction products such as TiC and Ti5Si3 were formed. The wetting of SAC-Ti on SiC was reaction-controlled. Interfacial reaction products TiC and Ti5Si3 were observed. The wetting activation energy in spreading stage was calculated to be 129.3 kJ/mol. Completely filled SiC/SiC joints were obtained using the filler with Ti content higher than 0.5 wt.%. The fillet height increased firstly then decreased with mounting Ti content. The shear strength of joints increased first with the addition of Ti then decreased with Ti content increasing to 2.0 wt.%. The highest shear strength of 35.7 MPa was obtained with SAC-1.5 Ti (wt.%) filler.
关键词： wetting,brazing,Ti addition,Sn0.3Ag0.7Cu,SiC ceramic
更新于2025-09-04 15:30:14
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Designing surface-enhanced Raman scattering (SERS) platforms beyond hotspot engineering: emerging opportunities in analyte manipulations and hybrid materials
摘要： Surface-enhanced Raman scattering (SERS) is a molecule-specific spectroscopic technique with diverse applications in (bio)chemistry, clinical diagnosis and toxin sensing. While hotspot engineering has expedited SERS development, it is still challenging to detect molecules with no specific affinity to plasmonic surfaces. With the aim of improving detection performances, we venture beyond hotspot engineering in this tutorial review and focus on emerging material design strategies to capture and confine analytes near SERS-active surfaces as well as various promising hybrid SERS platforms. We outline five major approaches to enhance SERS performance: (1) enlarging Raman scattering cross-sections of non-resonant molecules via chemical coupling reactions; (2) targeted chemical capturing of analytes through surface-grafted agents to localize them on plasmonic surfaces; (3) physically confining liquid analytes on non-wetting SERS-active surfaces and (4) confining gaseous analytes using porous materials over SERS hotspots; (5) synergizing conventional metal-based SERS platforms with functional materials such as graphene, semiconducting materials, and piezoelectric polymers. These approaches can be integrated with engineered hotspots as a multifaceted strategy to further boost SERS sensitivities that are unachievable using hotspot engineering alone. Finally, we highlight current challenges in this research area and suggest new research directions towards efficient SERS designs critical for real-world applications.
关键词： non-wetting surfaces,porous materials,Surface-enhanced Raman scattering,SERS,plasmonic surfaces,chemical coupling,hotspot engineering,semiconductors,piezoelectric polymers,analyte manipulation,hybrid materials,graphene
更新于2025-09-04 15:30:14