Lichtinitiierte Polymer‐ und Polymerisationsreaktionen. 36. Mitt.: Photovernetzung vinlygruppenhaltiger Poly(dimethylsiloxane)

Müller, Uwe; Timpe, H.‐J.; Häusler, K. G.; Peters, Κ.; Wagner, R.

doi:10.1002/actp.1990.010410114

Cited by 8 publications

(3 citation statements)

References 6 publications

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“…Polymerization of elastomer thin films, based on PDMS can be readily reached through hydrosilylation or heat-induced cross-linking reactions involving catalysts [12]. Alternatively the cleavage of the functional groups can also be realized by radicalization with UV light [13]. The radicalization of functional groups was observed with MIR spectroscopy and can be elucidated by assuming two main crosslinking paths.…”

Section: Discussionmentioning

confidence: 99%

“…Covalent bonding can be realized either by heat-induced curing using a catalyst [12] or applying ultra-violet radiation to force the photo-initiated reaction of radicals [13,14]. Midinfrared (MIR)-spectroscopy, for example, can support the analysis of polymerization in vinyl-terminated PDMS under continuous illumination by means of a deuterium broadband lamp, avoiding any use of cross-linkers or catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Siloxane-based thin films for biomimetic low-voltage dielectric actuators

Töpper

Weiss

Osmani

et al. 2015

Sensors and Actuators A: Physical

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a b s t r a c tMolecular beam deposition of siloxane-based polymer thin films was employed to realize single-layer dielectric elastomer actuators. With molecular weights of 6000 and 28,000 g/mol, vinyl-terminated polydimethylsiloxane (PDMS) was evaporated under high-vacuum conditions at crucible temperatures between 100 and 180 • C. Both deposition rate and realizable film thickness showed linear dependency with respect to the crucible temperature and were significantly higher for PDMS with lower molecular weight. Optimized growth conditions for 6000 g/mol were obtained at 180 • C with a deposition rate of (130 ± 5) nm per hour and a maximal film thickness of (530 ± 1) nm. Thermally induced polymerization was observed to limit the maximum accessible evaporation temperature for hydride-terminated PDMS above 180 • C and for vinyl-terminated PDMS above 230 • C. Ultraviolet (UV) light induced polymerization of vinyl-terminated PDMS was successfully established via radicalization at the functional vinyl end groups of the chains. Atomic force microscopy nanoindentation of the UV-polymerized network reveals that the oligomer chain length determines the elastic modulus of the polymer layer. Manufactured as asymmetric cantilever structures, the bending characteristic gave evidence that a 200 nm-thin film, activated in the voltage range between 1 and 12 V, maintains the actuation compared to a 4 mthick, spin-coated film, operated between 100 and 800 V. The force of the presented 200 nm-thin film cantilever actuator was about 10 −4 N. This means that a multilayer actuator with more than 10 4 layers would reach forces comparable to natural muscles. Therefore, such nanostructures can qualify for medical applications for example to treat severe incontinence.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Siloxane-based thin films for biomimetic low-voltage dielectric actuators

Töpper

Weiss

Osmani

et al. 2015

Sensors and Actuators A: Physical

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show abstract

“…An increase of the refractive index (RI) can be achieved by vinyl-terminated (dimethyl)-(diphenyl) siloxane copolymers. The degree of cross-linkage is controlled through vinyl-functionalised polysiloxanes in combination with (methylhydro)-or (mercaptopropyl-methyl)-(dimethyl) siloxane copolymers [7,8]. The fraction of substituted siloxane units (RR´SiO) is about 7% for the prepolymers containing vinyl and mercaptopropyl groups as R´ and R = CH 3 .…”

Section: Methodsmentioning

confidence: 99%

Optimisation of an integrated optical evanescent wave absorbance sensor for the determination of chlorinated hydrocarbons in water

Mayer¹,

Bürck²,

Ache³

1996

Analytical and Bioanalytical Chemistry

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The suitability of an integrated optical chemical sensor for the determination of highly volatile chlorinated hydrocarbons in aqueous solutions has been proven. The analytes are detected by NIR absorption spectrometry in the evanescent field of an integrated optical strip waveguide generated in a BGG31 (Schott, Germany) glass substrate, which is coated with a hydrophobic polymer superstrate as sensing layer. It has been shown that the sensitivity increases when the refractive index of the superstrate is increased from 1.333 up to 1.46. Different UV-cured polysiloxanes with low cross sensitivity to water have been prepared. Due to the good light transmission properties of the IO-sensors prepared by this method, quantitative measurements have been performed with the model system trichloroethene (TCE) in water. A detection limit of 22 ppm has been found and the sensor response times (t(90)-value) are between five and fourteen minutes for a coating thickness of around 30 microm. The sensor response is totally reversible. The analyte desorbes in air within 2 min. The enrichment of trichloroethene in the polysiloxane coating can be described by film diffusion through the aqueous boundary layer as rate determining step.

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Photovernetzung von Siliconen. VII. Zum Einflu� der Siliconkette - eine kinetische Studie

Müller

Aguirre

1992

J. Prakt. Chem.

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Photocrosslinking of Silicones. VII. The Influence of the Silicone Backbone – a Kinetic Study The photo‐induced radical crosslinking of silicone containing pendant acrylate groups was investigated by nanosecond flash photolysis and photocalorimetry. From the results of the flash photolysis is inferred that the photochemically formed benzoyl radicals react with the acrylate groups of the system. A possible H‐abstraction from the methyl groups of the silicone backbone was not observed. The silicone backbone functions only as an internal solvent. Calorimetric measurements with model systems support these results. The polymerization process is inhibited by oxygen. From calorimetric results is inferred that oxygen both inhibits and terminates the polymerization process. Due to their high oxygen solubility the silicone units increase the oxygen influence on the crosslinking. The calorimetric measurements shows also that a direct bond between silicone backbone and the acrylate group reduces the oxygen influence. Also, in absence of oxygen a direct bonded acrylate group accelerates the polymerization rate.

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Lichtinitiierte Polymer‐ und Polymerisationsreaktionen. 36. Mitt.: Photovernetzung vinlygruppenhaltiger Poly(dimethylsiloxane)

Cited by 8 publications

References 6 publications

Siloxane-based thin films for biomimetic low-voltage dielectric actuators

Siloxane-based thin films for biomimetic low-voltage dielectric actuators

Optimisation of an integrated optical evanescent wave absorbance sensor for the determination of chlorinated hydrocarbons in water

Photovernetzung von Siliconen. VII. Zum Einflu� der Siliconkette - eine kinetische Studie

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