1,721,018 research outputs found
A soft-imprint technique for submicron-scale patterns. using a PDMS mold
No full textWe have investigated a novel soft-imprint technique for fabrication of submicron scale polymer structures that can be simply performed at room temperature by polymerization with an elastomeric polydimethylsiloxane (PDMS) mold. The proposed technique is a simple, cheap and reproducible method for the patterning of large areas, and allows the transfer of polymer patterns at the submicron scale without high pressures. The PDMS mold is placed on a fluid mixture of prepolymer and monomer after a brief UV exposure; full polymerization follows; and then the mold is removed. Scanning electron microscopy (SEM) and atomic force (AFM) observations confirm that the submicron scale polymer structures are produced without defects or distortion and with good pattern fidelity over a large area. (C) 2004 Elsevier B.V. All rights reserved
The fabrication of submicron patterns on curved substrates using a polydimethylsiloxane film mould
No full textSubmicron features have been formed on polymer-coated cylindrical and spherical substrates via hot-embossing with a polydimethylsiloxane (PDMS) film stamp, without the use of high pressure. The use of flexible PDMS moulds offers a unique advantage over conventional methods, because they cover curved substrates easily, maintaining good contact with the substrate even during the hot-embossing procedure. Using this approach, uniform submicron patterns have been easily generated on curved substrates without distortion or defect formation, eliminating the need for complex and expensive lithography processes
The fabrication of micropatterns of a 2D colloidal assembly by electrophoretic deposition
No full textIn this work, the fabrication technique for micropatterns of a colloidal assembly on a gold-patterned electrode surface using electrophoretic deposition is described. It was found that the micropatterns of a colloidal assembly were preferentially deposited onto the gold pattern region, when a patterned indium tin oxide (ITO) electrode using TEM-grids was introduced in the electrodeposition of colloidal particles. The use of an appropriate electrodeposition time resulted in an ordered colloidal assembly structure and prevented the unwanted aggregation of particles. The micropatterning of a colloidal assembly arises because ail electrohydrodynamic flow of the colloidal suspension towards the gold domains is induced by the variation of the current density of the gold-patterned electrode. The proposed method offers a robust way to fabricate colloidal assembly patterns, which have various applications
Microfabrication of polypyrrole using patterned ITO substrate by the soft-imprint technique
No full textThis paper represented an effective and versatile method to fabricate the microstructures of conducting polymer, polypyrrole (Ppy). We prepared polymer patterns as an insulating template on ITO glass using soft-imprint technique that is a simple method to create the polymeric microstructures. After the residual layer of polymer patterns on ITO was removed with reactive ion etching (RIE) process in order to expose selectively the bare ITO, the electropolymerization of Ppy was conducted using the patterned ITO as an electrode. As a results, Ppy grew selectively only on the bare ITO, not on the remaining polymer features. In other words, the polymer patterns formed by the soft-imprint are acting as good barrier during the electropolymerization. Thus, two-/three-dimensional various microstructures of Ppy were fabricated with good resolution over a large area. (c) 2005 Elsevier B.V. All rights reserved
Micropatterns of colloidal assembly on chemically patterned surface
No full textMicropatterns of colloidal assembly were fabricated by the wetting/dewetting Of Suspensions on chemically patterned polydimethylsiloxane (PDMS). With the aid of plasma oxidation using screen masks, we fabricated the hydrophilic/hydrophobic patterns on the PDMS surface and dropped the suspensions of colloidal particles (210 or 410nm diameter particles on such patterned substrate). In the evaporation process, the colloidal suspensions were split and drawn from the hydrophobic domains to the hydrophilic domains via the wetting/dewetting process, and wetted only the hydrophilic domains to form an ordered colloidal assembly. In our experimental, the aqueous suspension with ethanol offered better results of the microarrays of colloidal assembly with ordered microstructures because of the low surface tension and fast evaporation rate of ethanol. The proposed method was applied to fabricate the micropatterns of colloidal assembly with various size of colloidal particles and patterned domains. (c) 2005 Elsevier B.V. All rights reserved
A soft-imprint technique for submicron structure fabrication via in situ polymerization
No full textWe have investigated a novel soft-imprint technique for the fabrication of submicron scale polymer structures that can be simply performed at room temperature by polymerization with an elastomeric polydimethylsiloxane (PDMS) mould. The proposed technique is a simple, cheap and reproducible method for the patterning of large areas, and that allows the transfer of polymer patterns at the submicron scale without high pressures. The PDMS mould is placed on a fluid mixture of prepolymer and monomer after a brief UV exposure, full polymerization follows, and then the mould is removed. SEM and AFM observations confirm that the submicron scale polymer structures are produced without any defect or distortion and with good pattern fidelity over a large area
Effect of diblock copolymers on morphology and mechanical properties for syndiotactic polystyrene/ethylene-propylene copolymer blends
No full textInterfacial agents are often used to compatibilize immiscible polymer blends. They are known to reduce the interfacial tension, homogenize the morphology, and improve adhesion between phases. In this study, two diblock copolymers of styrene/ethylene-propylene (SEP), which have different molecular weights, were used to compatibilize a blend of syndiotactic polystyrene (sPS) 75% and ethylene-propylene rubber (EPR) 25% so as to extend the applications of sPS as incoming thermoplastics. The morphological analysis and emulsification curve, which relates the average size of the dispersion particles to the concentration of diblock copolymers added, was used to investigate the efficiency of the interfacial agents on the blend morphology. A notched izod impact test and a tensile test were also performed to determine the compatibilization effect of different molecular weight copolymers on the mechanical properties of the blends and to establish links between morphology and mechanical properties. Results suggest that the lower molecular weight diblock copolymer showed an effective emulsifying capacity for sPS/ERP immiscible blend in morphology and mechanical properties. (C) 2004 Wiley Periodicals, Inc
Fabrication of patterned electroluminescent polymers with microcontact printing
No full textFor most practical applications, it is essential to fabricate micro- or nano-scale polymer electrolurninescent (EL) devices and pixel arrays. Microcontact printing, which uses a patterned elastomer (usually PDMS) as the mold to generate or transfer the pattern offers immediate advantages. Here we describe a method of patterning polymeric EL materials based on microcontact printing using PDMS mold. In this technique, we use the self-assembled monolayer (SAM) system of alkanephosphonic acids on ITO substrate, and patterned EL polymer is formed on the SAM-modified ITO substrate
Fabrication fo patterned electroluminescent polymers with microcontact printing
No full textFor most practical applications, it is essential to fabricate micro- or nanoscale polymer electroluminescent (EL) devices and pixel arrays. Although several methods to pattern EL polymers have been used previously: photolithography, laser ablation, and ink-jet printing, these techniques have limitations such as damage of EL materials.
A new powerful lithographic technique, ‘soft lithography’, has been developed as an alternative to photolithography for micro- and nanofabrication. This technique uses a patterned elastomer (usually PDMS) as the mold, stamp, or mask to generate or transfer the pattern. Soft lithography offers immediate advantages over photolithography and other conventional microfabrication techniques. Here we describe a method of patterning polymeric EL materials based on microcontact printing using PDMS stamp. In this technique, we use the self-assembled monolayer (SAM) system of alkanephosphonic acids on ITO substrate, and patterned EL polymer is formed on the SAM-modified ITO substrate
Patterning polymer light-emitting diodes by micromolding in capillary
No full textHere we describe a method of patterning electroluminescent (EL) polymers using micromolding in capillary (MIMIC). MIMIC is the one of the lithographic methods based on the microfludics among the soft lithography using a patterned poly(dimethylsiloxane) (PDMS) elastomer. The patterned microstructures of poly(dioctylfluorene) (PDOF), poly(p-phenylenevinylene) (PPV), and poly(2-methoxy-5-2'-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) were fabricated by MIMIC for polymer light-emitting diodes (PLEDs). In addition, the solution viscosity effect on MIMIC process was studied. Finally, a PLED device was fabricated using the patterned EL polymer microstructure and a patterned emission image was obtained. (c) 2005 Elsevier B.V. All rights reserved
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