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Your search keyword '"Bastiaansen, C. W. M."' showing total 95 results
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95 results on '"Bastiaansen, C. W. M."'

1. Fully reversible transition from Wenzel to Cassie-Baxter states on corrugated superhydrophobic surfaces

Author

Vrancken, R. J., Kusumaatmaja, H., Hermans, K., Prenen, A. M., Pierre-Louis, O., Bastiaansen, C. W. M., and Broer, D. J.

Subjects
Condensed Matter - Soft Condensed Matter, Condensed Matter - Materials Science, Physics - Fluid Dynamics
Abstract

Liquid drops on textured surfaces show different dynamical behaviors depending on their wetting states. They are extremely mobile when they are supported by composite solid-liquid-air interfaces (Cassie-Baxter state) and immobile when they fully wet the textured surfaces (Wenzel state). By reversibly switching between these two states, it will be possible to achieve large control over the fluid dynamics. Unfortunately, these wetting transitions are usually prevented by surface energy barriers. We demonstrate here a new and simple design paradigm, consisting of parallel grooves of appropriate aspect ratio, that allows for a controlled, barrierless, and reversible switching of the wetting states upon the application of electrowetting. We report a direct observation of the barrierless dynamical pathway for the reversible transitions between the Wenzel (collapsed) and the Cassie-Baxter (suspended) states and present a theory that accounts for these transitions, including detailed lattice-Boltzmann simulations., Comment: 24 pages, 5 figures, To appear in Langmuir. The supporting movies can be found at: http://www.mpikg-golm.mpg.de/th/people/halim/movies/

Published
2009

2. Anisotropic drop morphologies on corrugated surfaces

Author

Kusumaatmaja, H., Vrancken, R. J., Bastiaansen, C. W. M., and Yeomans, J. M.

Subjects
Condensed Matter - Soft Condensed Matter, Condensed Matter - Materials Science
Abstract

The spreading of liquid drops on surfaces corrugated with micron-scale parallel grooves is studied both experimentally and numerically. Because of the surface patterning, the typical final drop shape is no longer spherical. The elongation direction can be either parallel or perpendicular to the direction of the grooves, depending on the initial drop conditions. We interpret this result as a consequence of both the anisotropy of the contact line movement over the surface and the difference in the motion of the advancing and receding contact lines. Parallel to the grooves, we find little hysteresis due to the surface patterning and that the average contact angle approximately conforms to Wenzel's law as long as the drop radius is much larger than the typical length scale of the grooves. Perpendicular to the grooves, the contact line can be pinned at the edges of the ridges leading to large contact angle hysteresis., Comment: 22 pages, 10 figures, accepted for publication in Langmuir

Published
2008
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3. InP-based two-dimensional photonic crystals filled with polymers

Author

van der Heijden, R., Carlstrom, C. F., Snijders, J. A. P., van der Heijden, R. W., Karouta, F., Notzel, R., Salemink, H. W. M., Kjellander, B. K. C., Bastiaansen, C. W. M., Broer, D. J., and van der Drift, E.

Subjects
Physics - Optics
Abstract

Polymer filling of the air holes of Indium Phosphide based two-dimensional photonic crystals is reported. After infiltration of the holes with a liquid monomer and solidification of the infill in situ by thermal polymerization, complete filling is proven using scanning electron microscopy. Optical transmission measurements of a filled photonic crystal structure exhibit a redshift of the air band, confirming the complete filling., Comment: To be published in Appl. Phys. Lett

Published
2006
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4. Engineering Education on the 'Fuzzy' Front End: A High-Technology Entrepreneurship Model

Author

Crawford, G. P., Broer, D. J., and Bastiaansen, C. W. M.

Abstract

We have developed a university entrepreneurship program, culminating in a prototype and business plan, with five objectives: (1) value for all academic participants' (2) introduction to engineering issues for students; (3) refinement of engineering students' "soft" skills; (4) training for students in creating value out of embryonic ideas; and (5) a genuine entrepreneurship opportunity for students who wish to pursue a start-up company. The framework is disclosed in the context of three case studies. Furthermore, educational outcomes are derived and discussed based on participant evaluations and faculty reflection. Value creation is evaluated in terms of student performance in graduation exams, in external competitions, industrial interest, investment, intellectual property creation, and market intelligence. Finally, factors that add value to or redirect university research are discussed in the context to better serve society. (Contains 2 figures.)

Published
2006
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9. Electrospinning of p-Aramid Fibers

Author

Yao, J., Jin, J., Lepore, Emiliano, Pugno, Nicola, Bastiaansen, C. W. M., Peijs, T., and Stimuli-responsive Funct. Materials & Dev.

Abstract

Electrospun poly (p-phenylene terephthalamide) (PPTA) fibers with diameters between 275 nm and 15 µm were obtained from anisotropic solutions, albeit that the spinning process was difficult to control. Key solution parameters like conductivity, surface tension, and viscosity were used to compare the spinnability of these anisotropic solutions with common polymer solutions in order to better understand the challenges of spinning such solutions. Mechanical properties of the electrospun p-aramid single fibers were evaluated and it was found that Young's modulus and tensile strength increased dramatically with decreasing fiber diameter. A maximum Young's modulus and tensile strength of 59 and 1.1 GPa, respectively were found and a geometrical model for the size-dependent Young's modulus was developed to predict fiber properties based on rigid-rod chains down to the nanoscale.

Published
2015

10. Methodologies for high-performance electrospun fibers

Author

Ton Peijs, Yao, J., Bastiaansen, C. W. M., and Stimuli-responsive Funct. Materials & Dev.

Abstract

Electrospinning is a rapidly growing polymer processing technology as it provides a viable and simple method to create ultra-fine continuous fibers. This paper presents a review of the mechanical properties of electrospun fibers and particularly focuses on methodologies to generate high strength and high modulus nanofibers.

Published
2015

20. InP-based two-dimensional photonic crystals filled with polymers

Author

van der Heijden, R., primary, Carlström, C. F., additional, Snijders, J. A. P., additional, van der Heijden, R. W., additional, Karouta, F., additional, Nötzel, R., additional, Salemink, H. W. M., additional, Kjellander, B. K. C., additional, Bastiaansen, C. W. M., additional, Broer, D. J., additional, and van der Drift, E., additional

Published
2006
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44. Glassy photomechanical liquid-crystal network actuators for microscale devices.

Author

Oosten, C. L. van, Harris, K. D., Bastiaansen, C. W. M., and Broer, D. J.

Subjects
ACTUATORS, LIQUID crystal devices, LIQUID crystals, AUTOMATIC control systems, MOLECULES
Abstract

In light-driven liquid-crystal network (LCN) actuators, large performance improvements are obtained by varying the orientation of the molecular director through the thickness of the film actuator. Experiments show that sub-millimeter bending radii are achieved using a splayed molecular orientation. Systems with a splayed or twisted nematic (TN) director profile drive greater amplitude and faster bending than uniaxial planar systems with the same chemical composition. The bending radii of these systems are predicted using a simple model including effects of light intensity, material composition and actuator thickness. [ABSTRACT FROM AUTHOR]

Published
2007
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47. TiO2Nanoparticle–Photopolymer Composites for Volume Holographic Recording

Author

Sánchez, C., Escuti, M. J., van Heesch, C., Bastiaansen, C. W. M., Broer, D. J., Loos, J., and Nussbaumer, R.

Abstract

A new and efficient photopolymer for the recording of volume holograms is presented. The material comprises a mixture of UV‐sensitive acrylates and grafted titanium dioxide nanoparticles with an average size of 4 nm. We report the formation of holographic gratings with refractive‐index modulation amplitudes of up to 15.5 × 10–3—an improvement of more than a factor of four over the base material without nanoparticles—while maintaining a low level of scattering and a high transparency in the visible‐wavelength range. The influence of the composition of the acrylate system on the final properties of the holographic material is also investigated and discussed. The presence of multifunctional monomers favors the compositional segregation of the different components, while the addition of monofunctional acrylate, highly compatible with the grafting of the nanoparticles, favors the dilution of these nanoparticles.

Published
2005
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48. Hydrophilic Elastomers for Microcontact Printing of Polar Inks

Author

Trimbach, D. C., Al-Hussein, M., Jeu, W. H. de, Decre, M., Broer, D. J., and Bastiaansen, C. W. M.

Abstract

A moderately hydrophilic, thermoplastic elastomer (poly(ether-ester)) was investigated as a stamp material for microcontact printing of a polar ink:  pentaerythritol-tetrakis-(3-mercaptopropionate). Stamps with a relief structure were produced from this polymer by hot embossing, and a comparison was made with conventional poly(dimethylsiloxane) (PDMS) and oxygen-plasma-treated PDMS. It is shown that the hydrophilic stamps can be used for the repetitive printing (without re-inking) of at least 10 consecutive patterns, which preserve their etch resistance, and this in rather sharp contrast to conventional and oxygen plasma-treated PDMS stamps. It is argued that these enhanced printing characteristics of the hydrophilic stamps originate from an improved wetting and solubility of polar inks in the hydrophilic stamp.

Published
2004

49. Block Copolymer Thermoplastic Elastomers for Microcontact Printing

Author

Trimbach, D., Feldman, K., Spencer, N. D., Broer, D. J., and Bastiaansen, C. W. M.

Abstract

Two commercial thermoplastic block copolymer elastomers with a high stiffness were investigated as stamp materials for microcontact printing and compared to conventional poly(dimethylsiloxane) (PDMS). Stamps with a relief structure were produced by hot embossing techniques, utilizing the thermoplastic properties of these rubberlike block copolymers. It is shown that the stamps based on these copolymers are able to transfer a thiol ink to a gold substrate. After printing, the thiol ink acts as an etch resist, which indicates that a coherent self-assembled monolayer is formed. Like PDMS stamps, specific copolymer stamps can be used for repeated printing without re-inking. Moreover, the higher stiffness of the thermoplastic stamps increases the load above which structural collapse occurs by a factor of 10−15 in comparison to that of identical PDMS stamps, which is potentially useful in the reproduction of structures which are sensitive to sagging, buckling, or pairing. An example is presented of relief structures, which are accurately reproduced with the thermoplastic elastomers, in contrast to identical chemically cross-linked PDMS stamps.

Published
2003

50. Photo-Initiated Polymerization of Liquid Crystalline Thiol-Ene Monomers in Isotropic and Anisotropic Solvents

Author

Wilderbeek, H. T. A., Meer, M. G. M. van der, Bastiaansen, C. W. M., and Broer, D. J.

Abstract

We report on the photoinitiated polymerization of phenyl benzoate-based liquid crystalline (LC) thiol-ene monomers in isotropic and anisotropic solvents. The mixing behavior of the thiol-ene monomers with anisotropic cyanobiphenyl solvents was investigated, and unique reactive LC mixtures are formed that exhibit variable mesophases at ambient temperatures. Using size exclusion chromatography, the conversion of the thiol-ene monomers was studied in isotropic solvents and in anisotropic solvents as a function of several parameters, such as the irradiation time, polymerization temperature, and monomer concentration. Indications for the existence of a polymerization ceiling temperature effect were observed which was more pronounced for lower initial monomer concentrations. The in situ photopolymerization of the LC thiol-ene monomers in anisotropic media leads to a variety of morphological structures, ranging from intriguing threadlike architectures to dendritic crystalline structures. The morphological changes that occur during the polymerization process are complex, and several approaches toward the enhanced control over the resulting morphologies are discussed. The results and insights presented here could potentially lead to new architectures and enhanced optical and electrooptical properties of devices.

Published
2002
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