The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Albertus P H J Schenning - One of the best experts on this subject based on the ideXlab platform.
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Tuning MEMS cantilever devices using Photoresponsive Polymers
Smart Materials and Structures, 2019Co-Authors: Nathan Jackson, Albertus P H J Schenning, Kamlesh Kumar, Oskar Z. Olszewski, Michael G. DebijeAbstract:Microelectromechanical systems (MEMS) energy harvesting devices have had limited commercial success partly due to the frequency mismatch between the device and the vibration source. Tuning the cantilever device is one possible solution but developing a tuneable MEMS device is difficult. This paper demonstrates a novel method of tuning a MEMS cantilever device post-fabrication by using light responsive azobenzene liquid crystal Polymers (LCP). Light exposure causes the Photoresponsive Polymers to change their elastic modulus, thus affecting the resonant frequency of the device. The Photoresponsive Polymer was integrated with three different MEMS cantilever substrates including: LCP, parylene, and silicon. The three cantilever beams all demonstrated changes in resonant frequency when exposed to UV light of 10.4%, 8.13%, and 4.86%, respectively. The change in resonant frequency is dependent on the stiffness of the substrate, the thickness of the azo-LCP, the intensity and duration of the light exposure, and the wavelength of the light. The results in this paper validate that light responsive Polymers can be used to reduce the frequency of MEMS cantilevers post-fabrication, which could lead to developing devices that can be precisely tuned for specific applications.
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Photoresponsive Polymer hydrogel coatings that change topography
Responsive polymer surfaces, 2017Co-Authors: Jelle E Stumpel, Jeroen Ter Schiphorst, Albertus P H J SchenningAbstract:This chapter provides a brief overview of the principles as well as the potential applications of Photoresponsive hydrogel films, which change surface topography. It discusses the operating mechanisms that lead to topographical changes. Changes in topography can affect the wettability of a surface, which is an interesting characteristic for making self‐cleaning coatings. The chapter also discusses Polymer films that are useful for the development of self‐cleaning films. It then discusses responsive materials, for cell culturing and microfluidics applications. The chapter further shows that appealing Photoresponsive Polymer hydrogel coatings that change topography can be fabricated, which holds great promise in a variety of fields ranging from microfluidic devices to biomedical applications. When the structures of the topography are in the micrometer size regime, they influence the wettability of the surface. Two types of wetting can be defined: Wenzel and Cassie‐Baxter.
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Responsive Polymer Surfaces: Dynamics in Surface Topography - Photoresponsive Polymer Hydrogel Coatings that Change Topography
Responsive Polymer Surfaces, 2017Co-Authors: Jelle E Stumpel, Jeroen Ter Schiphorst, Albertus P H J SchenningAbstract:This chapter provides a brief overview of the principles as well as the potential applications of Photoresponsive hydrogel films, which change surface topography. It discusses the operating mechanisms that lead to topographical changes. Changes in topography can affect the wettability of a surface, which is an interesting characteristic for making self‐cleaning coatings. The chapter also discusses Polymer films that are useful for the development of self‐cleaning films. It then discusses responsive materials, for cell culturing and microfluidics applications. The chapter further shows that appealing Photoresponsive Polymer hydrogel coatings that change topography can be fabricated, which holds great promise in a variety of fields ranging from microfluidic devices to biomedical applications. When the structures of the topography are in the micrometer size regime, they influence the wettability of the surface. Two types of wetting can be defined: Wenzel and Cassie‐Baxter.
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Patterned oscillating topographical changes in Photoresponsive Polymer coatings
Soft matter, 2017Co-Authors: Matthew Hendrikx, Albertus P H J Schenning, Dirk J. BroerAbstract:The light-induced surface topography of a liquid crystal Polymer coating is brought into a patterned oscillatory deformation. A dichroic photo-responsive azobenzene is co-aligned with the planar oriented nematic liquid crystal network molecules which makes the surface deformation sensitive to polarized UV light. Locally selective actuation is achieved in coatings with a complex alignment pattern. Dynamic oscillation, as controlled by the actuation and relaxation kinetics of the Polymer, is obtained by a continuous change in the polarization of the UV source. The atypical deformation at the defect lines between the domains is of special interest. The amplitude and presence of the oscillation can be manipulated by changing the ratio between blue and UV light and by varying the ambient temperature of the coating.
Nathalie Katsonis - One of the best experts on this subject based on the ideXlab platform.
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Preparation of biomimetic Photoresponsive Polymer springs
Nature Protocols, 2016Co-Authors: Supitchaya Iamsaard, Elise Villemin, Fabrizio Lancia, Stephen P. Fletcher, Sarah-jane Aβhoff, Nathalie KatsonisAbstract:Materials that change shape on illumination can be used in soft robotics and artificial muscles. This protocol describes how to make Photoresponsive Polymer springs using liquid crystals, chiral dopants and a photo-switch derived from azobenzene. Polymer springs that twist under irradiation with light, in a manner that mimics how plant tendrils twist and turn under the effect of differential expansion in different sections of the plant, show potential for soft robotics and the development of artificial muscles. The soft springs prepared using this protocol are typically 1 mm wide, 50 μm thick and up to 10 cm long. They are made from liquid crystal Polymer networks in which an azobenzene derivative is introduced covalently as a molecular photo-switch. The Polymer network is prepared by irradiation of a twist cell filled with a mixture of shape-persistent liquid crystals, liquid crystals having reactive end groups, molecular photo-switches, some chiral dopant and a small amount of photoinitiator. After postcuring, the soft Polymer film is removed and cut into springs, the geometry of which is determined by the angle of cut. The material composing the springs is characterized by optical microscopy, scanning electron microscopy and tensile strength measurements. The springs operate at ambient temperature, by mimicking the orthogonal contraction mechanism that is at the origin of plant coiling. They shape-shift under irradiation with UV light and can be pre-programmed to either wind or unwind, as encoded in their geometry. Once illumination is stopped, the springs return to their initial shape. Irradiation with visible light accelerates the shape reversion.
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Preparation of biomimetic Photoresponsive Polymer springs
Nature Protocols, 2016Co-Authors: Supitchaya Iamsaard, Elise Villemin, Sarah Jane Aßhoff, Fabrizio Lancia, Stephen P. Fletcher, Nathalie KatsonisAbstract:Polymer springs that twist under irradiation with light, in a manner that mimics how plant tendrils twist and turn under the effect of differential expansion in different sections of the plant, show potential for soft robotics and the development of artificial muscles. The soft springs prepared using this protocol are typically 1 mm wide, 50 μm thick and up to 10 cm long. They are made from liquid crystal Polymer networks in which an azobenzene derivative is introduced covalently as a molecular photo-switch. The Polymer network is prepared by irradiation of a twist cell filled with a mixture of shape-persistent liquid crystals, liquid crystals having reactive end groups, molecular photo-switches, some chiral dopant and a small amount of photoinitiator. After postcuring, the soft Polymer film is removed and cut into springs, the geometry of which is determined by the angle of cut. The material composing the springs is characterized by optical microscopy, scanning electron microscopy and tensile strength measurements. The springs operate at ambient temperature, by mimicking the orthogonal contraction mechanism that is at the origin of plant coiling. They shape-shift under irradiation with UV light and can be pre-programmed to either wind or unwind, as encoded in their geometry. Once illumination is stopped, the springs return to their initial shape. Irradiation with visible light accelerates the shape reversion.
Jaana Vapaavuori - One of the best experts on this subject based on the ideXlab platform.
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supramolecular design principles for efficient Photoresponsive Polymer azobenzene complexes
Journal of Materials Chemistry C, 2018Co-Authors: Jaana Vapaavuori, Geraldine C Bazuin, Arri PriimagiAbstract:Noncovalent binding of azobenzenes to Polymers allows harnessing light-induced molecular-level motions (photoisomerization) for inducing macroscopic effects, including photocontrol over molecular alignment and self-assembly of block coPolymer nanostructures, and photoinduced surface patterning of Polymeric thin films. In the last 10 years, a growing body of literature has proven the utility of supramolecular materials design for establishing structure–property–function guidelines for Photoresponsive azobenzene-based Polymeric materials. In general, the bond type and strength, engineered by the choice of the Polymer and the azobenzene, influence the photophysical properties and the optical response of the material system. Herein, we review this progress, and critically assess the advantages and disadvantages of the three most commonly used supramolecular design strategies: hydrogen, halogen and ionic bonding. The ease and versatility of the design of these Photoresponsive materials makes a compelling case for a paradigm shift from covalently-functionalized side-chain Polymers to supramolecular Polymer–azobenzene complexes.
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Supramolecular design principles for efficient Photoresponsive Polymer–azobenzene complexes
Journal of Materials Chemistry C, 2018Co-Authors: Jaana Vapaavuori, C. Geraldine Bazuin, Arri PriimagiAbstract:Noncovalent binding of azobenzenes to Polymers allows harnessing light-induced molecular-level motions (photoisomerization) for inducing macroscopic effects, including photocontrol over molecular alignment and self-assembly of block coPolymer nanostructures, and photoinduced surface patterning of Polymeric thin films. In the last 10 years, a growing body of literature has proven the utility of supramolecular materials design for establishing structure–property–function guidelines for Photoresponsive azobenzene-based Polymeric materials. In general, the bond type and strength, engineered by the choice of the Polymer and the azobenzene, influence the photophysical properties and the optical response of the material system. Herein, we review this progress, and critically assess the advantages and disadvantages of the three most commonly used supramolecular design strategies: hydrogen, halogen and ionic bonding. The ease and versatility of the design of these Photoresponsive materials makes a compelling case for a paradigm shift from covalently-functionalized side-chain Polymers to supramolecular Polymer–azobenzene complexes.
Arri Priimagi - One of the best experts on this subject based on the ideXlab platform.
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supramolecular design principles for efficient Photoresponsive Polymer azobenzene complexes
Journal of Materials Chemistry C, 2018Co-Authors: Jaana Vapaavuori, Geraldine C Bazuin, Arri PriimagiAbstract:Noncovalent binding of azobenzenes to Polymers allows harnessing light-induced molecular-level motions (photoisomerization) for inducing macroscopic effects, including photocontrol over molecular alignment and self-assembly of block coPolymer nanostructures, and photoinduced surface patterning of Polymeric thin films. In the last 10 years, a growing body of literature has proven the utility of supramolecular materials design for establishing structure–property–function guidelines for Photoresponsive azobenzene-based Polymeric materials. In general, the bond type and strength, engineered by the choice of the Polymer and the azobenzene, influence the photophysical properties and the optical response of the material system. Herein, we review this progress, and critically assess the advantages and disadvantages of the three most commonly used supramolecular design strategies: hydrogen, halogen and ionic bonding. The ease and versatility of the design of these Photoresponsive materials makes a compelling case for a paradigm shift from covalently-functionalized side-chain Polymers to supramolecular Polymer–azobenzene complexes.
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Supramolecular design principles for efficient Photoresponsive Polymer–azobenzene complexes
Journal of Materials Chemistry C, 2018Co-Authors: Jaana Vapaavuori, C. Geraldine Bazuin, Arri PriimagiAbstract:Noncovalent binding of azobenzenes to Polymers allows harnessing light-induced molecular-level motions (photoisomerization) for inducing macroscopic effects, including photocontrol over molecular alignment and self-assembly of block coPolymer nanostructures, and photoinduced surface patterning of Polymeric thin films. In the last 10 years, a growing body of literature has proven the utility of supramolecular materials design for establishing structure–property–function guidelines for Photoresponsive azobenzene-based Polymeric materials. In general, the bond type and strength, engineered by the choice of the Polymer and the azobenzene, influence the photophysical properties and the optical response of the material system. Herein, we review this progress, and critically assess the advantages and disadvantages of the three most commonly used supramolecular design strategies: hydrogen, halogen and ionic bonding. The ease and versatility of the design of these Photoresponsive materials makes a compelling case for a paradigm shift from covalently-functionalized side-chain Polymers to supramolecular Polymer–azobenzene complexes.
Matthew Y Sfeir - One of the best experts on this subject based on the ideXlab platform.
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preferential charge generation at aggregate sites in narrow band gap infrared Photoresponsive Polymer semiconductors
Advanced Optical Materials, 2018Co-Authors: Dana B Sulas, Alexander E London, Lifeng Huang, Lihua Xu, Zhenghui Wu, Tse Nga Ng, Bryan M Wong, Cody W Schlenker, Jason D Azoulay, Matthew Y SfeirAbstract:Author(s): Sulas, Dana B; London, Alexander E; Huang, Lifeng; Xu, Lihua; Wu, Zhenghui; Ng, Tse Nga; Wong, Bryan M; Schlenker, Cody W; Azoulay, Jason D; Sfeir, Matthew Y | Abstract: © 2018 WILEY-VCH Verlag GmbH a Co. KGaA, Weinheim Infrared organic photodetector materials are investigated using transient absorption spectroscopy, demonstrating that ultrafast charge generation assisted by Polymer aggregation is essential to compensate for the energy gap law, which dictates that excited state lifetimes decrease as the band gap narrows. Short sub-picosecond singlet exciton lifetimes are measured in a structurally related series of infrared-absorbing coPolymers that consist of alternating cyclopentadithiophene electron-rich “push” units and strong electron-deficient “pull” units, including benzothiadiazole, benzoselenadiazole, pyridalselenadiazole, or thiadiazoloquinoxaline. While the ultrafast lifetimes of excitons localized on individual Polymer chains suggest that charge carrier generation will be inefficient, high detectivity for Polymer:PC71BM infrared photodetectors is measured in the 0.6 l λ l 1.5 µm range. The photophysical processes leading to charge generation are investigated by performing a global analysis on transient absorption data of blended Polymer:PC71BM films. In these blends, charge carriers form primarily at Polymer aggregate sites on the ultrafast time scale (within our instrument response), leaving quickly decaying single-chain excitons unquenched. The results have important implications for the further development of organic infrared optoelectronic devices, where targeting processes such as excited state delocalization over aggregates may be necessary to mitigate losses to ultrafast exciton decay as materials with even lower band gaps are developed.
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preferential charge generation at aggregate sites in narrow band gap infrared Photoresponsive Polymer semiconductors
Advanced Optical Materials, 2018Co-Authors: Dana B Sulas, Alexander E London, Lifeng Huang, Bryan M Wong, Cody W Schlenker, Jason D Azoulay, Matthew Y SfeirAbstract:Author(s): Sulas, DB; London, AE; Huang, L; Xu, L; Wu, Z; Ng, TN; Wong, BM; Schlenker, CW; Azoulay, JD; Sfeir, MY | Abstract: © 2018 WILEY-VCH Verlag GmbH a Co. KGaA, Weinheim Infrared organic photodetector materials are investigated using transient absorption spectroscopy, demonstrating that ultrafast charge generation assisted by Polymer aggregation is essential to compensate for the energy gap law, which dictates that excited state lifetimes decrease as the band gap narrows. Short sub-picosecond singlet exciton lifetimes are measured in a structurally related series of infrared-absorbing coPolymers that consist of alternating cyclopentadithiophene electron-rich “push” units and strong electron-deficient “pull” units, including benzothiadiazole, benzoselenadiazole, pyridalselenadiazole, or thiadiazoloquinoxaline. While the ultrafast lifetimes of excitons localized on individual Polymer chains suggest that charge carrier generation will be inefficient, high detectivity for Polymer:PC71BM infrared photodetectors is measured in the 0.6 l λ l 1.5 µm range. The photophysical processes leading to charge generation are investigated by performing a global analysis on transient absorption data of blended Polymer:PC71BM films. In these blends, charge carriers form primarily at Polymer aggregate sites on the ultrafast time scale (within our instrument response), leaving quickly decaying single-chain excitons unquenched. The results have important implications for the further development of organic infrared optoelectronic devices, where targeting processes such as excited state delocalization over aggregates may be necessary to mitigate losses to ultrafast exciton decay as materials with even lower band gaps are developed.