In the past two decades, we have witnessed significant progress in developing high performance stimuli-responsive polymeric materials. This review focuses on recent developments in the preparation and application of patterned stimuli-responsive polymers, including thermoresponsive layers, pH/ionic-responsive hydrogels, photo-responsive film, magnetically-responsive composites, electroactive composites, and solvent-responsive composites. Many important new applications for stimuli-responsive polymers lie in the field of nano- and micro-fabrication, where stimuli-responsive polymers are being established as important manipulation tools. Some techniques have been developed to selectively position organic molecules and then to obtain well-defined patterned substrates at the micrometer or submicrometer scale. Methods for patterning of stimuli-responsive hydrogels, including photolithography, electron beam lithography, scanning probe writing, and printing techniques (microcontact printing, ink-jet printing) were surveyed. We also surveyed the applications of nanostructured stimuli-responsive hydrogels, such as biotechnology (biological interfaces and purification of biomacromoles), switchable wettability, sensors (optical sensors, biosensors, chemical sensors), and actuators.

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Fabrications and Applications of Stimulus-Responsive Polymer Films and Patterns on Surfaces: A Review

Photorefractive properties of polyphosphazenes containing carbazole-based multifunctional chromophores

Robust, sensitive and facile method for detection of F−, CN− and Ac− anions

A carbazole-based photorefractive polyphosphazene was prepared via post-azo-coupling reaction. The polymer shows a low glass transition temperature of 50 °C, and has an excellent solubility in common organic solvents, which can easily be fabricated into an optically transparent film with long-term stability. The nonlinear optical effects, including two-beam-coupling and four-wave-mixing, were studied at 633 nm under room temperature. A gain coefficient of 79 cm −1 and a diffraction efficiency of 18% were observed at zero external electric field without any added plasticizer or sensitizer.

A carbazole-based photorefractive polyphosphazene prepared via post-azo-coupling reaction

Although some azo-carbazole derivatives attached on or doped into inert polymers are known to show photorefractive effect without external electric field, the origin of their asymmetric energy transfer in two-beam coupling experiments were unknown. We made the two-beam coupling experiment followed by sample translation and one-beam diffraction at 633 nm for thick films composed of 3-[(4-nitrophenyl)]azo-9H-carbazole-9-ethanol (NACzEtOH) and poly(methylmethacrylate), finding that photoinduced gratings grew in several minutes accompanied with phase displacement of the gratings, but the phase shift was not always synchronized with the refractive index modulation. We reformulated the Kogelnik’s coupled-wave theory with strict energy conservation law for analysis. Comparison of the grating growth and erasure at 532 nm to Disperse Red 1 (DR1), the most well-known azo dye showed that the photoisomerization was dominant at this wavelength and that the azo-carbazole dyes were faster in response time and more resistive to erasure than DR1.

Photoinduced grating formation in a polymer containing azo-carbazole dyes

https://ir.nctu.edu.tw/bitstream/11536/334/1/A1997XU82300009.pdf

Hang Ching Wang

Papers

The effect of laser wavelength on the photorefractive characteristics of PMDA-DR19 based photorefractive polymeric materials