Stimuli-Responsive Polymer Composite One-Dimensional Photonic Crystals

Photonic crystals, which are structures that present periodic modulation of the refractive index, have been a subject of much interest in materials science community for many years. According to the variation of refractive index and period in space, photonic crystals can be classified as one-dimensional, two-dimensional and three-dimensional photonic crystals. They display potential applications in physical devices, chemical and biological sensors and so on. Recently, more and more responsive phtonic crystals cre created to meet daily demand. Most of the responsive photonic crystals are based on there-dimensional order structures which are difficult to prepare in large area. Furthermore, not uniform colors, bad stability, high cost and complicated preparing methods limit their applications. As the simplest photonic structure, 1D architectures such as Bragg stack and distributed Bragg mirrors as responsive photonic crystals have attracted great attention. With simple preparing process and low cost, the preparation and investigating of ID photonic crystals (1DPCs) become very important. Optical properties of 1DPCs can be tuned by introuducing stimuli-responsive materials into their structure units, which impart them great potential applications in many fields.In the thesis, we have successfully prepared several kinds of polymer/TiO2 or pure polymer 1DPCs and investigated their basic optical properties. After that, introducing stimuli-responsive materials into the photonic structures to prepare responsive 1DPCs which can be used ascolorful sensors. At last 1DPCs can be processed by UV light cross-linking or degradation, leading them to be as photonic paper or photonic nose sensors.In the second chaper, organic/inorganic hybrid 1DPCs are achieved through alternating titania and PHEMA by spin-coating. Tuning of their optical properties is realized by changing the number of layers, incident angles, period, defect and humidity. Optical property changing of the 1DPCs can be displayed by the change of the stop band position, bandwidth, the peak intensity and the appearing of the pass band. Upon exposing the 1DPCs to water vapor, the photonic stop band shifts to longer wavelength. The responsive process reaches balance after 150 s. At different concentrated water vapor, the photonic stop band shifts different positons with different color change.In the third chapter, different responsive 1DPCs are prepared by introducing different kinds of stimuli-responisve polymer materials, which can be used as colorful sensors. As the polymer changes from PMMA-PEGDMA-PHEMA to PDMAEMA and totally protonted PDMAEMA, the polymer/titania hybrid 1DPCs can be used as organic solvent, pH and SCN-sensors respectively.In the last chapter, first, we have successfully prepared polymer photonic paper by alternatively spin-coating PMMA and PNIPAM-co-PGMA films, followed by a simultaneous UV and heating cross-linking process with water as ink. Second, a simple method for patterning PMMA-PEGDMA-PHEMA/TiO21DPCs is investigated. Colorful pattern can be produced by exposing the 1DPCs under UV light selectively. Due to the solvent sensitivity of the polymer layer, we can modulate the color of the pattern by dipping the 1DPCs into organic solvents, leading the prepared 1DPCs to be a wonderful colorful sensor with high selectivity.In our research system, due to the quick and simple preparing method, high optical quality, perfect stability, brilliant color, fast responsive speed, good repeatability and processing, the 1DPCs can be used in daily life in the future.