Preparationof Hydrogen-Bonded Blue Phase Liquid Crystal Networkand Investigation Its Photonic Band Gap Responsiveness

Intelligent material is a kind of perceived environmental stimulation, to analysis, processing, and judgment, and takes a certain way for effective response of the material. With self-assembled three-dimensional (3D), blue phase liquid crystal (BP-LCs) is an isotropic and three-dimensional (3D) photonic material, which attice parameters easily influenced by outside conditions change, so as to present a different photoelectric properties. As a result, BP-LCs has a broad application prospect of responsiveness photonic materials. The studies of responsive behavior of BP-LCs have mainly focused on photo, electric and thermal response.In this study, we report on a humidity-responsive sensor based on a BP-LC polymer network, which introducing acid hydrogen bonded dimers can be aggregated self-assembly to form the polymer BP-LCs, and processed further salinization.Here, the photopolymerizable LC crosslinker, hydrogen-bonded (H-bonded) photopolymerizable acid, chiral LC monoacrylate and photoinitiator are mixed to prepare the BP-LCs mixtures. Then, the BP-LCs mixtures was polymerized at BPI temperature range irradiated by ultraviolet (UV) light, in which the assembly of H-bonded assembly also happened. Finally, we use K.OH to salinizate the BP polymer film, therefore destroying the H-bond to form the porous structure. According to the different proportion of small molecules, different samples of swelling performance will also be different.In this study, as a result of the sample after absorbing water, the blue phase structure will swell, leading to the increase of the blue phase lattice constant, the red shift of reflection band will happen. On the contrary, it will be blue shift. The results show that, with different of BP polymer network’s mess density, the humidity responsiveness will be different. Over the same sample, under the condition of different humidity, the reflection band shift is also different. The results show that this type of blue phase polymer network for humidity change of reflected color change is reversible. Meanwhile, the alcohol such as ethanol can further help to improve the humidity-responsiveness. Our work demonstrates that the blue phase polymer network photonic materials because of its easy preparation, low price has great potential applications in the areas of optical sensors.