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 pattern...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.展开更多
In this study,functionally graded foam made of Inconel 625 superalloy was successfully produced using the template replication method,with open-cell polyurethane foams as a precursor.The products have a similar pore m...In this study,functionally graded foam made of Inconel 625 superalloy was successfully produced using the template replication method,with open-cell polyurethane foams as a precursor.The products have a similar pore morphology as the templates and adjacent layers were successfully sintered together by particle bonding.Sound absorption experiments on graded metallic foams reveal that the sound absorption at particular frequency ranges can be improved by various permutations of foam layers.For graded foam of two distinct pore sizes,a mathematical equation was proposed to predict the location of the intersection point of the sound absorption curves,thereby aiding in graded foam design.An increase in sound absorption coefficients by resonance-like effects can be introduced before the intersection points by placing the foam layer of smaller pore size nearer to the sound source.The sound absorption performances can be further customized when the thickness proportion of the pore sizes is changed and when the number of distinct pore sizes used is increased.The sound absorption performance at lower frequencies is generally boosted by resonance-like effects when the layer of foam with the largest pore size is placed furthest from the sound source.Given the same composition of foam with a fixed thickness proportion of pore sizes,one can introduce resonance-like effects to improve the sound absorption performance compared to other permutations while possibly satisfying weight requirements in practical applications.This study provides valuable insights and mathematical guidelines in the design and manufacturing of functionally graded metallic foam for specific applications.展开更多
The lotus leaf,paradigmatic in superhydrophobic research,exhibits a water contact angle ofθ=160.4˚±1.5˚and a sliding angle of 2˚±1˚,enabled by its micro-/nano-hierarchical architecture.Herein,we report a fa...The lotus leaf,paradigmatic in superhydrophobic research,exhibits a water contact angle ofθ=160.4˚±1.5˚and a sliding angle of 2˚±1˚,enabled by its micro-/nano-hierarchical architecture.Herein,we report a facile two-step protocol—micro-texture replication followed by fluorination—to fabricate flexible,low-adhesion,superhydrophobic films.Using polydimethylsiloxane(PDMS,part A)and curing agent(part B)as the matrix,biomimetic micro-cones were faithfully duplicated from a master mold,with matched elastic modulus,thermal stability which can withstand extreme conditions of 300℃,as well as inert chemical stability(100% ethanol resistance).Subsequent va-por-phase grafting of 1H,1H,2H,2H-perfluorodecyltriethoxysilane(PFDS)yielded robust fluorocarbon chains oriented outward,minimizing surface en-ergy.The resulting film possesses a static water contact angle of 158.3˚±1.2˚and a sliding angle of 3.1˚±0.4˚,surpassing the conventional benchmarks(WCA≥150˚,SA≤10˚).The material demonstrates significant potential for self-cleaning solar panels,anti-icing aircraft coatings,and corrosion-resistant marine surfaces.展开更多
基金Financial supports from the Natural Science Foundation of China(Nos.21074090 and 21374076)Tianjin Research Program of Application Foundation and Advanced Technology (No.13JCYBJC17100)
文摘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.
基金supported by A*STAR under the AME YIRG Grant(No.A20E6c0099)AME IAF-PP Grant(No.A1896a0034)。
文摘In this study,functionally graded foam made of Inconel 625 superalloy was successfully produced using the template replication method,with open-cell polyurethane foams as a precursor.The products have a similar pore morphology as the templates and adjacent layers were successfully sintered together by particle bonding.Sound absorption experiments on graded metallic foams reveal that the sound absorption at particular frequency ranges can be improved by various permutations of foam layers.For graded foam of two distinct pore sizes,a mathematical equation was proposed to predict the location of the intersection point of the sound absorption curves,thereby aiding in graded foam design.An increase in sound absorption coefficients by resonance-like effects can be introduced before the intersection points by placing the foam layer of smaller pore size nearer to the sound source.The sound absorption performances can be further customized when the thickness proportion of the pore sizes is changed and when the number of distinct pore sizes used is increased.The sound absorption performance at lower frequencies is generally boosted by resonance-like effects when the layer of foam with the largest pore size is placed furthest from the sound source.Given the same composition of foam with a fixed thickness proportion of pore sizes,one can introduce resonance-like effects to improve the sound absorption performance compared to other permutations while possibly satisfying weight requirements in practical applications.This study provides valuable insights and mathematical guidelines in the design and manufacturing of functionally graded metallic foam for specific applications.
文摘The lotus leaf,paradigmatic in superhydrophobic research,exhibits a water contact angle ofθ=160.4˚±1.5˚and a sliding angle of 2˚±1˚,enabled by its micro-/nano-hierarchical architecture.Herein,we report a facile two-step protocol—micro-texture replication followed by fluorination—to fabricate flexible,low-adhesion,superhydrophobic films.Using polydimethylsiloxane(PDMS,part A)and curing agent(part B)as the matrix,biomimetic micro-cones were faithfully duplicated from a master mold,with matched elastic modulus,thermal stability which can withstand extreme conditions of 300℃,as well as inert chemical stability(100% ethanol resistance).Subsequent va-por-phase grafting of 1H,1H,2H,2H-perfluorodecyltriethoxysilane(PFDS)yielded robust fluorocarbon chains oriented outward,minimizing surface en-ergy.The resulting film possesses a static water contact angle of 158.3˚±1.2˚and a sliding angle of 3.1˚±0.4˚,surpassing the conventional benchmarks(WCA≥150˚,SA≤10˚).The material demonstrates significant potential for self-cleaning solar panels,anti-icing aircraft coatings,and corrosion-resistant marine surfaces.
