showing 7 related works from this author
Creating Defined 3-D Defects Inside an Opaline Ormocer® Matrix with Two-Photon Lithography
2007
The creation of defined structures inside a synthetic opal is a key step toward applications in optics, where control of the propagation of light inside a photonic crystal is necessary. In a previous paper, we described the nanostructuring of Ormocer® to form inverse opals (Lange et al., Macromol. Rapid Commun. 2006, 27, 1746). Here, we report an application for this robust replica process in which defects can be directly produced within the PC by two-photon lithography. The holes of an inverse opal structure are first filled with a resin of similar refractive index. In this transparent material, polymerization can be initiated at defined places via two-photon lithography. After removal of …
Design, Synthesis, and Use of Y-Shaped ATRP/NMP Surface Tethered Initiator.
2015
Heterogeneous polymer brushes on surfaces can be easily formed from a binary initiator on a silicon oxide substrate where two different types of polymers can be grown side-by-side. Herein, we designed a new Y-shaped binary initiator using straightforward chemistry for “grafting from” polymer brushes. This initiator synthesis takes advantage of the Passerini reaction, a multicomponent reaction combining two initiator sites and one surface linking site. This Y-shaped binary initiator can be synthesized in three steps with a higher yield than other similar initiators reported in the literature, and can be performed on a multigram scale. We were able to attach the initiator to a silicon oxide s…
Non-ionic photo-acid generators for applications in two-photon lithography
2009
Non-ionic photoacid generators (PAGs) have been designed and synthesized for use in two-photon lithography (TPL). The chromophores in these new PAGs are covalently linked to the photocleavable group by a flexible joint. Their thermal stability, solubility and efficiency to produce acid under both one- and two-photon excitation were characterized. The potential of these PAGs for TPL was tested in two negative-tone resist systems relying on different mechanisms: free-radical/cationic polymerization or a cationically initiated cross-linking reaction. These PAGs needed lower threshold power for polymerization compared to a commercially available photoinitiator, isopropylthioxanthone, and a phot…
MEMS analogous micro-patterning of thermotropic nematic liquid crystalline elastomer films using a fluorinated photoresist and a hard mask process
2017
In this work, we present a method to pattern liquid crystal elastomers (LCEs) in the micrometer range without using any mechanical processing steps to prepare micron sized LCE actuators compatible with microelectromechanical system (MEMS) technology. Multi-layer spin-coating processes are developed to synthesise and structure 300–3500 nm thick LCE films. A water soluble sacrificial layer, a photoalignment layer and a LCE formulation, which is polymerised and crosslinked in its liquid crystal phase, are spin-coated successively onto a substrate. A fluorinated photoresist layer is used to structure LCE films with thicknesses up to 700 nm in a photolithographic and etching process. For thicker…
Ferroelectric block copolymers
1997
A block copolymer consisting of polystyrene and a side chain ferroelectric liquid crystalline polymer was synthesized using polymer analogous chemistry on a monodisperse poly(styrene-b-isoprene). Composition was adjusted to give lamellar microstructure after addition of the mesogenic side groups. If placed in an LC cell without orientation of domains, no ferroelectric response was observed. After shearing the thin film, presumably due to alignment of lamellae, a bistable ferroelectric switching could be detected.
3D defect engineering in polymer opals
2006
The possibility to create defined structures inside a synthetic opal is a key step towards applications in optics, where control of the propagation of light inside a photonic crystal is necessary. Here we report different methods for realizing defined embedded defects in opaline structures. Monodisperse colloids are synthesized by surfactant free emulsion polymerization of the acid labile monomer t-butyl-methacrylate (tBMA). The PtBMA colloids can be filled with sensitizer and photo acid generator and it is possible to crystallize them into photosensitive polymer opals. One method for the introduction of defects is a multilayer build-up of photo-labile (filled with photo acid generator) and…
High-Performance Electron-Transporting Polymers Derived from a Heteroaryl Bis(trifluoroborate)
2011
In this communication, we report that dipotassium aryl bis(trifluoroborate)s make stable and easy-to-purify yet reactive monomers under Suzuki polycondensation reactions. A bis(trifluoroborate) of 2-alkylbenzotriazole was prepared successfully and copolymerized with dibromobenzothiadiazole in the presence of a Pd catalyst and LiOH, yielding high molecular weight conjugated polymers. This polymer (P1) composed of all electron-accepting units shows excellent electron-transport properties (μ(e) = 0.02 cm(2) V(-1) s(-1)), which proves the value of the aryl bis(trifluoroborate) monomers and suggests that many other types of semiconducting polymers that could not be accessed previously can be syn…