We have developed a degradable photoresist that is responsive to pH and ultraviolet light (UV). This dual-responsive resist consists of 5,7-diacryloyloxy-4-methylcoumarin (fluorescent monomer), acrylic anhydride, and 3,6-dioxa-1,8-dithiooctane. It can be photocured using thiol–acrylate polymerization and photodimerization of coumarin moieties under 365 nm UV light exposure. The cured resist is degradable in aqueous solutions with pH > 7. The degradation process can be characterized by the change of fluorescence intensity in the aqueous solution. In this study, we have analyzed the properties of the degradation of the resist by changing the pH of the solution and its exposure time under 254 nm UV light. This UV exposure can induce photocleavage of the coumarin dimers. We then used these materials to fabricate micropatterns through nanoimprint lithography (NIL) process. Compared with other conventional degradable materials capable of NIL, the dual-responsive resist can help to clean the NIL mold easily at room temperature. This resist is also more environmentally friendly, is relatively low cost, can be faster to degrade, and is easier to characterize. It also has low volume shrinkage, which may have a valuable and positive effect on the development of NIL.

•Coumarin-modified microcapsules (CMMs) are fabricated via interfacial polymerization.•The CMMs possess particular fluorescence and photo-switchable property.•Different ultraviolet light can regulate the release behavior of CMMs.In this study, we propose one kind of photo-responsive microcapsule based on the coumarin-modified shell. The coumarin group firstly reacts with pentaerythritol on a stoichiometric basis and then etherifies with the polymerizable isocyanate group to obtain the shell material. To stabilize the shell structure, we fabricate coumarin-modified microcapsules (CMMs) via interfacial polymerization and 365 nm ultraviolet light irradiation. The particle size and surface morphology of microcapsules are measured by scanning electron microscopy and optical microscopy. After ultraviolet irradiation, the shell of CMMs exhibits variable fluorescence as well as reversible crosslinking and cleavage due to the [2 + 2] cyclization reaction. By introducing the fluorescent dye 2-anilino-6-dibutylamino-3-methylfluoran (ODB-2) into microcapsules, the controlled release behavior of CMMs can be measured by fluorescence microscope and fluorescence spectrophotometer. The CMMs exhibit distinct “on” state and “off” state separately under different ultraviolet light, achieving ODB-2 release and trapping. This result leads to precise characterization of controlled release property, which will be of interest in switchable microcapsules for drug delivery system and information recording device.Coumarin-modified microcapsules (CMMs) are fabricated via interfacial polymerization and photo-crosslinking reaction. The prepared CMMs possess particular fluorescence and controlled release property with the regulation of different ultraviolet light.Download high-res image (168KB)Download full-size image

We have developed a novel thermoresponsive photonic actuator based on three-dimensional SiO2 opal photonic crystals (PCs) together with liquid crystal elastomers (LCEs). In the process of fabrication of such a photonic actuator, the LCE precursor is infiltrated into the SiO2 opal PC followed by UV light-induced photopolymerization, thereby forming the SiO2 opal PC/LCE composite film with a bilayer structure. We find that this bilayer composite film simultaneously exhibits actuation behavior as well as the photonic band gap (PBG) response to external temperature variation. When the SiO2 opal PC/LCE composite film is heated, it exhibits a considerable bending deformation, and its PBG shifts to a shorter wavelength at the same time. In addition, this actuation is quite fast, reversible, and highly repeatable. The thermoresponsive behavior of the SiO2 opal PC/LCE composite films mainly derives from the thermal-driven change of nematic order of the LCE layer which leads to the asymmetric shrinkage/expansion of the bilayer structure. These results will be of interest in designing optical actuator systems for environment-temperature detection.Keywords: bending deformation; liquid crystal elastomer; opal photonic crystal; photonic band gap; thermoresponsive photonic actuator

•3D print technique is used to print flexible circuits.•Highly conductive PLA-graphene composites are fabricated for 3D printing.•2D and 3D flexible circuits are printed rapidly.•The flexible circuits exhibit superior conductivity and mechanical properties.Fused depositing modeling (FDM) is a fast, efficient process among 3D printing techniques. In this paper, we report the fabrication of the 3D printed flexible circuits based on graphene. Modified two-step in-situ reduced method is used to synthesize reduced graphene oxide (r-GO), whose conductivity can reach to 600 S/cm. Polylactic acid (PLA) and r-GO are mixed by melt blending. The SEM images show that the r-GO can be homogenous dispersed in the PLA. The 3D print-used composites filaments with the diameter of 1.75 mm are fabricated through melt extrusion. The conductivity of the composite filaments from 3D printer can reach to 4.76 S/cm (6 wt% r-GO). The orientation of r-GO occurs during the extrusion process, which contributing to increase the conductivity of the filaments. The composite also exhibit superior mechanical property. The printed 2D and 3D flexible circuits have strong interface bonding force between the layers. The filaments from 3D printer can replace the copper wire because of the high conductivity. This arbitrary 3D graphene-based structure printing technic may open a new prospect in electronic and energy storage fields.High conductive graphene flexible circuits are printed through 3D printing. PLA are chosen as the substrate of graphene. Graphene can be homodispersed in the PLA substrate.

We have developed a bio-inspired thermal-responsive micropatterned inverse opal film with dual structural colors based on liquid crystal elastomers (LCEs). Herein, inverse opal films are fabricated by infiltrating the LC precursor into silica opal photonic crystal templates followed by UV irradiation and then removing the silica spheres. Furthermore, the micropatterned inverse opal films with dual structural colors have been fabricated by a two-step photo-polymerization technique combining a DC electric field. The DC electric field is used to tune the lattice space of the silica opal templates at the second photo-polymerization stage. In addition, the photonic band gaps of the LCE inverse opal films with dual structural colors can be reversibly switched by temperature because of the thermally induced molecular orientation change of the LCEs. This approach to create bi-colored inverse opals with micropatterns opens up a new way to the development of display and photonic applications.

In this study, we report a new kind of chiral hybrid material which was prepared through three-dimensional (3D) assembly of silver nanoparticles (Ag NPs) into a 3D blue-phase (BP) polymer nanostructure template by in situ reduction of silver nitrate. A feature signal at plasmonic wavelengths of Ag NPs could be found in the circular dichroism spectra after assembly of Ag NPs within the 3D BP template due to the localized surface plasmon resonance of Ag NPs. Additionally, the chiral hybrid material not only shows a sensitive response to different amounts of Ag NPs but also exhibits pronounced sensitivity to different surrounding dielectric environments. These kinds of chiroptical hybrid materials can be valuable in a wide range of applications such as refractive sensing, protein inspection and other biomedical fields.

•The formation of Ag NPs is observed in pure aqueous solution without reductant and surfactant under ultrasonic condition.•In pure aqueous solution, the reactive route producing oxygen related to hydroxyl radicals (OHOH) is presented.•In alkaline aqueous solution, ultrafine Ag NPs with diameter of 8 nm are achieved via ultrasonic irradiation.•In alkaline aqueous solution, the effects of hydroxyl ions (OH−) on formation of Ag NPs are discussed detailedly.In this study, a simple and green method to synthesize silver nanoparticles (Ag NPs) in aqueous solution via ultrasonic irradiation has been developed. Ultrafine Ag NPs with average diameter of 8 nm were obtained through sonicating aqueous solution of sodium hydroxide (NaOH, 0.1 mM) with adding silver nitrate solution (AgNO3, 5.88 mM) drop by drop. In pure aqueous solution, the reactive route related to hydroxyl radicals (OHOH) is presented. Furthermore, in alkaline aqueous solution, the effects of hydroxyl ions (OH−) on formation of Ag NPs are discussed detailedly. The formation of Ag NPs was tracked by surface plasmon resonance (SPR) band of ultraviolet–visible (UV–Vis) spectrum; the morphology of the obtained Ag NPs was characterized through transmission electron microscopy (TEM); energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD) confirmed the formation of metallic Ag NPs.

In this study, we fabricated four new photobase generating monomers, in which carbamate units functioned as the photobase generating moieties, methacrylate units served as the polymerizable groups and four different groups, succinimido, camphorquinone 3-oximino, di-2-thienyl ketoximino and difuril dioximino units, acted as photosensitive species. The effect of different photosensitive species on the photochemical behavior of the monomers was investigated in detail. The results demonstrate that, among the four monomers, succinimido methacryloxyethyl carbamate (SMC) exhibits the most stable photobase generating property. Furthermore, a copolymer containing SMC is used for a fluorescence imaging material. The fluorescence spectrum of the fluorescamine-treated irradiated copolymer film showed a strong fluorescence in the range of 420–650 nm with a fluorescence maximum at 476 nm. The patterns in the copolymer films exhibit very distinct fluorescence images with colors of blue, green and red at certain observation wavelengths.

In this study, we developed a new kind of functional photoresist based on octamethacrylated polyhedral oligomeric silsesquioxane (MAPOSS) and fluorinated monomer as an ideal material for ultraviolet nanoimprint lithography (UV-NIL). We first optimized the synthesis of MAPOSS using the hydrolysis and condensation reactions of methacryloyl oxygen propyl trimethoxysilane. The hybrid photoresist formulations with MAPOSS and fluorinated additive were found to be effective materials for high-performance UV-NIL, which exhibited a preferable curing rate, Young's modulus and thermal stability. Additionally, the low shrinkage and low surface energy of the curing film allows for easier transfer of relief features with excellent imprint reliability for UV-based NIL techniques. These characteristics of fluorinated silsesquioxane-based photoresists make them suitable as inexpensive and convenient components in UV-NIL processes.

•Flexible microelectronic circuits were fabricated via the screen-printing technique using ternary composites PANI/Ag/MWCNTs.•PANI/Ag/MWCNTs were prepared by in situ polymerization of PANI on Ag/MWCNT binary composites in SDBS solution.•The ratio of the reactants (aniline to Ag/MWCNTs) could influence the microstructures and morphologies of the PANI layer.•The conductivity of the ternary composites could be controlled between 10−8 and 2.4 × 102 S cm−1.•The resolution of circuits patterns was 0.2 mm min-linewidth with the thickness of 40 μm.Flexible microelectronic circuits were fabricated via the screen-printing technique using ternary composites of polyaniline, silver nanoparticles, and multi-walled carbon nanotubes (PANI/Ag/MWCNTs) with protonation of dodecyl benzenesulfonic acid. These ternary composites were prepared by in situ polymerization of PANI on Ag/MWCNT binary composites, which were synthesized prior by ultrasonication of AgNO3 in ethylene glycol solution dispersed with MWCNTs. In the process of synthesis, the ratio of the reactants (aniline to Ag/MWCNTs) could influence the microstructures and morphologies of the PANI layer, which would then significantly affect the conductivity of the composites. By tuning this ratio, the conductivity of the composites could be controlled between 10−8 and 2.4 × 102 S cm−1. Meanwhile, the existence of a PANI functional layer increased not only the dispersities but also the processabilities of the composites, and accelerated the preparation of the ternary composites into conductive patterns. Finally, well-defined patterns were fabricated by depositing the ternary composites on different flexible substrates using the screen-printing technique.

•Highly monodispersed (3.0–4.2 nm) nonaqueous small-sized (3.7 ± 0.1 nm) silver nano-colloids were obtained.•Forming mechanism of the silver nanoparticles by this method is firstly proposed.•The optimal experimental conditions for this method have been found.•Silver/polymer nanocomposites can be easily formed by ultraviolet exposure.Highly monodispersed nonaqueous small-sized (3.7 ± 0.1 nm) silver nano-colloids were successfully synthesized by in situ synthesis using silver dodecanoate as organic precursor, 3,3,5-trimethylcyclohexyl methacrylate (TMCHMA) as solvent, and triethylamine (Et3N) as promoter. The obtained silver nanoparticles were characterized by ultraviolet–visible (UV–vis) absorption spectrophotometer, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The results showed that the highly monodispersed silver nanoparticles with diameter in the range of 3.0 nm to 4.2 nm and have face centered cubic (FCC) crystal structure. The possible forming mechanism of the core–shell structured silver nanoparticles and silver/polymer nanocomposites was proposed. By thermogravimetric analysis (TG) and energy dispersive X-ray spectroscopy (EDX) spectrometer of silver nanoparticles, it was speculated that dodecanoic acid together with UV-curable monomer (i.e., TMCHMA) consisted of the shell of silver nanoparticles. The ratio of monomer and silver precursor, the dropping rate of Et3N and reaction temperature were the three key factors to determine particle size and size distribution. The photopolymerizable silver nano-colloids were able to disperse in nonaqueous solvent. Silver/polymer nanocomposites were prepared by addition of photo initiator and a short-term UV exposure on the silver nano-colloids.

In this study, we present several simple but effective methods to stabilize blue phases (BPs) and investigate their possible stabilization mechanisms. An achiral mesogen monomer with a branched end group (MF-LCM) and chiral hydrogen-bonded assemblies (CHBAs) were prepared and were applied to extend the BP temperature range of a simple cyanobiphenyl compound (8CB). Increasing the achiral mesogen monomer content results in a widened BP range, which is could be due to molecular shape of the achiral MF-LCM and their interactions with the bulk Ch-LCs molecules. Meanwhile, the result demonstrates that CHBAs also have a positive influence on broadening the BP temperature range, this expansion of the BP temperature range was induced by the chiral effect and viscosity effect. Taking these two factors into account, the widest BP temperature range in the LC sample with MF-LCM and CHBAs was 13.0 °C during the cooling process. Furthermore, LC mixtures with MF-LCM and di-functional liquid crystalline monomer (C6M) were irradiated by UV light to induce polymerization. The BP temperature range was broadened obviously, and the widest BP range has been extended even up to about 41.0 °C, which results from the traditional polymer stabilization mechanism and BP polymer templating effect. These explorations provide some useful insight into the molecular design, chiral effect and polymer network towards stabilizing BP.

In this study, we develop a kind of novel photoswitchable chiral azo switches bearing both axially chiral binaphthyl center and single tetrahedrally chiral center with different configurations. The influence of the configuration of the tetrahedrally chiral centers and the introduction of a rigid structure on the helical twisting power (HTP) of the chiral azo switch was addressed in detail. Our results demonstrate that the import of the tetrahedrally chiral center dramatically decreased the HTP of the axially chiral azo switch, while the rigid long core increased the HTP. According to a molecular simulation based on Gaussian03 calculations at the B3LYP/6-31G(d) level, both the molecular configuration and the molecular aspect ratio were found to be the key factors influencing the HTP of the chiral azo switch. Finally, we utilize the above chiral azo switch to fabricate a photo-addressed, flexible liquid crystal device. This work provides an insight into the relationship between the chiral effect and molecular structure of chiral switches and their potential applications for photonic and display fields.

The stabilization of liquid crystalline blue phases (BPs) from novel hydrogen-bonded (H-bonded) bent-shaped and T-shaped assemblies (HBAs) has been described for the first time in this study. Different kinds of H-bonded bent-shaped and T-shaped molecules were assembled, and then used to broaden the BP temperature range of liquid crystal (LC) samples. The results demonstrate that the temperature range of BPs is significantly influenced by HBA dopants, in which the widest BP temperature range was 15.1 °C. Moreover, the lower temperature of BPs is very close to room temperature, which is of benefit to the application of BPs in LC displays. Additionally, according to the experimental analysis and molecular simulations, the physical mechanism of the BP stabilization by bent-shaped and T-shaped molecules is mainly related to the molecular geometry and is not dependent on the LC phase. This study has developed a new and facile strategy to widen the BP temperature range from the aspect of the molecular design.

In this study, we have fabricated well-defined silver nanowires by an ultraviolet (UV) irradiation technique in the presence of phosphomolybdic acid (PMo), which acted as a catalyst and stabilizing agent. The effect of fabrication parameters on the morphology of silver nanowires, such as initial concentrations of reactants, AgNO3:PMo ratio, UV irradiation time, and temperature, are presented in detail. This suggests that the appropriate amount of PMo plays a relevant role in the formation of the silver nanowires, and temperature is another important factor determining the morphology of the silver nanowires. Furthermore, the antibacterial properties of silver nanowires was investigated against Escherichia coli, Staphylococcus aureus and Bacillus subtilis, and the mean diameters of the inhibition zones are 15.4 mm, 20.9 mm and 26.7 mm, respectively. This work provides a simple and green method for the synthesis of silver nanowires in aqueous solution with promising antibacterial properties.

We present a pressure-sensitive polymer dispersed cholesteric liquid crystal (PDCLC) device, in which a cholesteric liquid crystal (ChLC) is encapsulated by a polymer network via an ultraviolet photopolymerization induced phase separation method. The effects of the acrylate monomer concentration and functionality on the network morphology, and the electro-optic behaviour of the PDCLC device were studied. The results demonstrated that the electro-optic properties, including reflectivity and the contrast ratio of the pressure-sensitive device, were improved as the ChLC droplet size increased. An appropriate network density in the system limited the flow of the ChLC and allowed high-resolution lines to be drawn on the device. Additionally, the critical pressure switching of the device from a focal conic state to a planar state was investigated. The device developed in this study has promising applications in many fields such as flexible display devices and optical sensors.

In this study, we demonstrate a simple and effective method for the microcapsulation of cholesteric liquid crystals (Ch-LCs) by using interfacial polymerization. Herein, isophorone diisocyanate (IPDI) and water were used to form a thin polyurea shell of microcapsulates, and different kind of Ch-LCs materials with left-handed or right-handed helical structure were utilized as core materials, the factors influencing the morphology of Ch-LCs microcapsule such as weight ratio of Ch-LCs/polyurea, emulsification rate, agitation rate and emulsifier content were investigated in detail. Meanwhile, Ch-LCs films based on microcapsules and polymer binder exhibit distinct optical characteristics, thermal tuning of red-green-blue reflection in a Ch-LC film can be achieved, in which the core material of cholesteryl LCs mixture has a great temperature-dependence of pitch length. And Ch-LCs film with a double-handed circularly polarized light reflection band and their temperature switching was also demonstrated. These special optical properties make the novel Ch-LCs microcapsules interesting for potential application in many fields such as information recording, optical components, flat displays, photonic materials etc.

In this study, we demonstrate a simple approach of fabricating conductive ultraviolet curable (UV) inkjet ink composed of silver nano-colloids and water-based UV resin. A type of stable silver nano-colloids with uniform size is prepared by oxidation–reduction reaction and polymer-coating process in a mixed aqueous solution of silver nitrate, glucose, triethylamine and poly (vinyl pyrrolidone). The results show that concentration of silver nitrate and glucose, the amount of glucose and the input rate of triethylamine have different effect on the shapes and sizes of the products. An environment friendly UV conductive inkjet ink is further produced by adding water-based UV resin and photo-initiator into nano-colloids. A conductive pattern can then be achieved by the following steps: ink-jet printing UV conductive ink on flexible polyimide substrate, evaporation of water on heating stage, curing under UV spot light source and sintering in muffle furnace. The effect of different silver content, thickness of conductive pattern and sintering temperature on the conductivity performance are investigated in detail. These novel composites studied here have a great potential application for flexible photonics and electronics.Highlights► Silver nano-colloids made of PVP, Et3N, AgNO3 and glucose. ► Combination of water-based UV resin and silver nano-colloids for conductive inkjet ink. ► The conductive line was gained by ink-jet printing, evaporation of water, UV curing and sintering.

In this work, the photosensitive paste was prepared. It was comprised of inorganic particles and a photosensitive organic component. The inorganic particles included glass, ceramics, and metals. The organic component should contain at least the following photosensitive materials: photosensitive monomers, photoreactive copolymer and photopolymerization initiators. The photoreactive copolymer played a role of an adhesive in the photosensitive paste. Meanwhile in the development stage, the carboxyl groups of the copolymer reacted with the alkalescent developer. Following this, the unexposed part must be removed and an excellent pattern can be formed. A series of three-component acrylic copolymers (MAA/St/MMA) were designed, and then synthesized via free radical polymerization. Subsequently glycidyl methacrylate (GMA) was employed to modify the prepared copolymers through ring-opening reactions between the carboxyl groups and the epoxide groups. Eventually the photosensitive copolymers were obtained and used to form the barrier ribs of PDPs. The chemical structure, glass transition temperature, acid value and molecular weight of photosensitive copolymers had different effects on the structure and pattern of PDP barrier ribs. Through analyzing effects of different polymer performance parameters on the patterns of barrier ribs, the optimal photosensitive copolymer was acquired.

In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal (Ch-LC) monomers mixture containing a photopolymerizable chiral H-bonded assembly (PCHA). The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band (SRB) of the cholesteric polymer film in solution with pH > 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH < 7 hardly changed. This pH sensitivity in solutions with pH > 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by −OH− and −K+ ions in the alkaline solution. In contrast, it couldn’t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.

In this study, novel photopolymerizable chiral hydrogen-bonded self-assembled complexes (PCHSCs) were fabricated, which were derived from photopolymerizable 4-(6-acryloyloxyhexyloxy) benzoic acid (AHBA, proton donor) and chiral pyridine derivatives (proton acceptor). Their structures were characterized by fourier transform infrared (FT-IR) and the proton nuclear magnetic resonance (1H-NMR) spectoscopy. The thermal stability, phase behaviors and helical twisted power (HTP) characteristics of the PCHSC were investigated by measuring the variable-temperature FT-IR spectrum, differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and the Cano wedge. The results demonstrate that all the PCHSCs have good thermal stability within a temperature range, and the pitch length of all the cells containing the PCHSCs increases with increasing temperature, which is due to the fact that the HTP values of all the PCHSCs decrease with an increase of temperature. What's more, the introduction of AHBA leads to chiral enhancement of the PCHSCs. Based on the above results, a polymer stabilized cholesteric liquid crystals (PSCLCs) composite with the above PCHSCs was prepared and the thermal-optical characteristics of the PSCLCs film were investigated. The results confirm that the reflective wavelength of the PSCLCs film before and after irradiation can be thermally switched to reflect green and red color from the initial state reflecting a blue/green color with the temperature increasing from 30 °C to 75 °C. On the basis of this mechanism, the novel material in this study can be used as optical/photonic paper, optical sensors and LCs displays, etc.

We have developed a bio-inspired thermal-responsive micropatterned inverse opal film with dual structural colors based on liquid crystal elastomers (LCEs). Herein, inverse opal films are fabricated by infiltrating the LC precursor into silica opal photonic crystal templates followed by UV irradiation and then removing the silica spheres. Furthermore, the micropatterned inverse opal films with dual structural colors have been fabricated by a two-step photo-polymerization technique combining a DC electric field. The DC electric field is used to tune the lattice space of the silica opal templates at the second photo-polymerization stage. In addition, the photonic band gaps of the LCE inverse opal films with dual structural colors can be reversibly switched by temperature because of the thermally induced molecular orientation change of the LCEs. This approach to create bi-colored inverse opals with micropatterns opens up a new way to the development of display and photonic applications.

In this study, we present several simple but effective methods to stabilize blue phases (BPs) and investigate their possible stabilization mechanisms. An achiral mesogen monomer with a branched end group (MF-LCM) and chiral hydrogen-bonded assemblies (CHBAs) were prepared and were applied to extend the BP temperature range of a simple cyanobiphenyl compound (8CB). Increasing the achiral mesogen monomer content results in a widened BP range, which is could be due to molecular shape of the achiral MF-LCM and their interactions with the bulk Ch-LCs molecules. Meanwhile, the result demonstrates that CHBAs also have a positive influence on broadening the BP temperature range, this expansion of the BP temperature range was induced by the chiral effect and viscosity effect. Taking these two factors into account, the widest BP temperature range in the LC sample with MF-LCM and CHBAs was 13.0 °C during the cooling process. Furthermore, LC mixtures with MF-LCM and di-functional liquid crystalline monomer (C6M) were irradiated by UV light to induce polymerization. The BP temperature range was broadened obviously, and the widest BP range has been extended even up to about 41.0 °C, which results from the traditional polymer stabilization mechanism and BP polymer templating effect. These explorations provide some useful insight into the molecular design, chiral effect and polymer network towards stabilizing BP.

In this study, we develop a kind of novel photoswitchable chiral azo switches bearing both axially chiral binaphthyl center and single tetrahedrally chiral center with different configurations. The influence of the configuration of the tetrahedrally chiral centers and the introduction of a rigid structure on the helical twisting power (HTP) of the chiral azo switch was addressed in detail. Our results demonstrate that the import of the tetrahedrally chiral center dramatically decreased the HTP of the axially chiral azo switch, while the rigid long core increased the HTP. According to a molecular simulation based on Gaussian03 calculations at the B3LYP/6-31G(d) level, both the molecular configuration and the molecular aspect ratio were found to be the key factors influencing the HTP of the chiral azo switch. Finally, we utilize the above chiral azo switch to fabricate a photo-addressed, flexible liquid crystal device. This work provides an insight into the relationship between the chiral effect and molecular structure of chiral switches and their potential applications for photonic and display fields.

In this study, novel photopolymerizable chiral hydrogen-bonded self-assembled complexes (PCHSCs) were fabricated, which were derived from photopolymerizable 4-(6-acryloyloxyhexyloxy) benzoic acid (AHBA, proton donor) and chiral pyridine derivatives (proton acceptor). Their structures were characterized by fourier transform infrared (FT-IR) and the proton nuclear magnetic resonance (1H-NMR) spectoscopy. The thermal stability, phase behaviors and helical twisted power (HTP) characteristics of the PCHSC were investigated by measuring the variable-temperature FT-IR spectrum, differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and the Cano wedge. The results demonstrate that all the PCHSCs have good thermal stability within a temperature range, and the pitch length of all the cells containing the PCHSCs increases with increasing temperature, which is due to the fact that the HTP values of all the PCHSCs decrease with an increase of temperature. What's more, the introduction of AHBA leads to chiral enhancement of the PCHSCs. Based on the above results, a polymer stabilized cholesteric liquid crystals (PSCLCs) composite with the above PCHSCs was prepared and the thermal-optical characteristics of the PSCLCs film were investigated. The results confirm that the reflective wavelength of the PSCLCs film before and after irradiation can be thermally switched to reflect green and red color from the initial state reflecting a blue/green color with the temperature increasing from 30 °C to 75 °C. On the basis of this mechanism, the novel material in this study can be used as optical/photonic paper, optical sensors and LCs displays, etc.