CO_(2)-diluted CH_(4)-air premixed spherical flames with microwave-assisted spark ignition

The performance of microwave-assisted spark ignition(MAI)under exhaust gas recirculation conditions was explored with CO_(2)-diluted CH-air premixed spherical flames in a constant volume combustion chamber.The flame kernel radius at 5 ms after spark started was selected to evaluate the property of MAI for CO_(2)dilution ratio of 0-20%and equivalence ratio of 0.6-1.4 with 1 kHz microwave pulse repetition frequency under 0.2 MPa ambient pressure.The results showed that the addition of microwave induced some wrinkles on the flame surface and strongly deformed the flame.MAI expanded the limit of CO_(2)dilution ratio to 16%with an equivalence ratio of 0.75,in which case the spark only(SI)failed to ignite the mixture.With the CO_(2)dilution ratio increasing,the wrinkles induced by microwave pulses decreased apparently,and the enhancement value of MAI peaked at 4%CO_(2)dilution ratio.The effect of microwave was considered in two aspects,namely,reaction kinetics and thermal effect,which shows a“trade-off”as CO_(2)dilution ratio rose.With 8%volume of CO_(2)added,the flammable interval(equivalence ratio 0.6-1.2)of mixture in SI mode shrunk,and MAI can maintain a flammable interval consistency with the case that no CO_(2)was added.

Light-Responsive Polyblend Films with Reconfigurable Surface Micropatterns as Rewritable Information Storage Media

Stimulus-sensitive surfaces with tunable morphologies exhibit a wide range of applications in the fields of surface science and engineering.Herein,a cost-effective yet practical strategy is proposed to fabricate photo-sensitive patterning surface on film/substrate wrinkle system based on an azo-containing polyblend.By manipulating the stress field of the bilayer system globally and/or locally upon the stress relaxation triggered by the reversible cis-trans isomerization of the azobenzene,heating/cooling triggered surface wrinkles on the polyblend films could be tailor-made with visible-light-irradiation.Notably,upon selective photo-irradiation,bespoke surface patterns may be cyclically generated or eliminated,allowing these reconfigurable patterned polyblend surfaces to be used as rewritable information storage media for non-ink printing.The as-prepared photo-printed information patterns with high-resolution are shown to be rewritable for multiple cycles and legible for over 90 d in dark ambient conditions.This study not only provides a versatile strategy for flourishing the stimulus-sensitive systems,but also sheds light on the stress relaxation-triggered morphological evolution of the wrinkling polyblend films.

Snakeskin‑Inspired Hierarchical Winkled Surface for Ultradurable Superamphiphobic Fabrics via Short‑Fluorinated Polymer Reactive Infusion

Durable superamphiphobic surfaces are highly desired for real-world applications such as self-cleaning,anti-fouling,personal protection,and functional sportswear.However,challenges still exist in constructing robust superamphiphobic surfaces by using short-fluorinated polymers as one of the promising alternatives for environmentally unfriendly long perfluorinated side-chain polymers.Hierarchical patterns on biological skins endow the creatures with a specific surface for survival.Here,a facile strategy was proposed to generate hierarchical wrinkles for ultradurable superamphiphobic fabrics by simulating the deformation adaptability of snakeskin.Snake-like hierarchical winkling was constructed by the infusion of reactive perfluorooctyltriethoxysilane(FOS)in a wet chemical plus vapor polymerization process.Upon the infusion of FOS,the mismatch of shrinkage caused by gradient crosslinking leads to the formation of a soft wrinkled poly(perfluorooctyl trieth-oxysilane)(poly-FOS)surface.Such a snakeskin-like hierarchical wrinkled surface and high fluorine density of poly-FOS endowed the treated superamphiphobic fabrics with high water resistance(contact angle 169°),castor oil resistance(154°),and extraordinary durability(withstanding 100 standard laundries,15,000 rubbing cycles and strong acid and alkali solu-tions).Moreover,a superamphiphobic surface can be formed on various substrates,including fabric,wood,paper,and glass.This work thus gives new insights into the environmentally friendly manufacture of ultradurable superamphiphobic fabrics.

高灵敏度和高线性度的可拉伸应变传感器的分层结构设计

对柔性电子设备日益增长的需求使得开发具有高灵敏度和高线性度的传感器更加迫切.由于拉伸应变下不可逆结构损伤诱导电阻线性急剧增加,现有的可拉伸应变传感器难以完美地同时实现这两个特性.针对这一问题,本文提出了一种兼具表面褶皱和体相梯度孔隙的新型分级互连结构,利用水热活化机制精确控制纳米级褶皱间距,通过调控相分离中热力学和动力学行为构筑出体相梯度多孔结构,通过改变器件两侧曲率实现各向异性特征,深入研究各种设计的功效、量化几何结构对灵敏度的有效贡献和追踪形态演变.基于器件显著的灵敏度和各向异性,所制备的传感器能够有效监测静态和动态位移、表面运动、二维应变信号变化以及预测液位随时间变化.本工作为实现高质量的感知能力提供了一种广泛适用、适应性强、可扩展且具有成本效益的方法.

Controlled fabrication of hierarchically microstructured surfaces via surface wrinkling combined with template replication

In this paper,we present a simple method by combining surface wrinkling and template replication to create a series of hierarchical structures on polydimethylsiloxane（PDMS） elastomer.The primary stable lined patterns are formed by duplicating commercialized compact disk and digital versatile disk with PDMS.The secondary microscale patterns are from surface wrinkling,which is elicited by oxygen plasma（OP） treatment of the prestrained PDMS stamp followed with the prestrain release.By systematically varying the OP exposure duration,the prestrain,and the angle（θ） between the primary pattern orientation and the prestrain direction,we obtain highly ordered well-organized composite patterns from different patterning techniques and with different length scales and mechanical stabilities.

Trans-scale surface wrinkling model and scaling relationship analysis of stiff film-compliant substrate structures

The self-assembly of surface-order structures based on the surface wrinkling of stiff film-compliant substrate structures(SFCS)is potentially useful in the fabrication of functional devices,the manufacture of superhydrophobic or self-cleaning surfaces,and so on.Due to the influence of the intrinsic characteristic length(g),the surface wrinkling behavior of SFCS at the micro scale is different from that at the macro scale.In this work,based on the strain gradient theory,a trans-scale surface wrinkling model for SFCS is established.First,the effectiveness of this model is verified by previous experiments.Then,based on the model and dimensional analysis,the effect of g on the surface wrinkling behavior is investigated,and the scaling relationship of surface wrinkling of SFCS at different scales is analyzed.The results show that the influence of g cannot be neglected when the film thickness decreases to the one comparable to g.At the micro scale,g will lead to the increase of the critical wrinkling wavelength and load.In addition,the scaling relationship of surface wrinkling at the micro scale will not follow the traditional one.Our study explains the underlying mechanism of the dissimilarity of surface wrinkling behaviors of SFCS at different scales and lays a theoretical foundation for the precise control of surface-order structures.

Facile and robust strategy to antireflective photo-curing coating through self-wrinkling

We reported a facile and bio-inspired strategy for obtaining antireflective （AR） coating through polymerization-induced self-wrinkling. Upon irradiation of light, the complex wrinkle micro-patterns with different morphologies were generated spontaneously on the surface of coating during photo-cross- linking, which enables the photo-curing coating can decrease reflection. The resulting photo-curing coating exhibits a high transmittance over 90% and low reflection below 5% ～ 8%, with an efficiency anti- reflection of 4% ～ 7%; compared to the flat blank coating. The successful application of these AR coatings with wrinkles pattern to encapsulate the thin film solar cells results in appreciable photovoltaic performance improvement of more than 4% ～ 8%, which benefits from the decrease of the light reflection and increase of optical paths in the photoactive layer by the introduction of wrinkling pattern. Furthermore, the efficiency improvements of the solar cells are more obvious, with a remarkable increase of 8.5%, at oblique light incident angle than that with vertical light incident angle