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Opposite Self-Folding Behavior of Polymeric Photoresponsive Actuators Enabled by a Molecular Approach
摘要： The ability to obtain 3D polymeric objects by a 2D-to-3D shape-shifting method is very appealing for polymer integration with different materials, from metals in electronic devices to cells in biological studies. Such functional reshaping can be achieved through self-folding driven by a strain pattern designed into the molecular network. Among polymeric materials, liquid crystalline networks (LCNs) present an anisotropic molecular structure that can be exploited to tailor internal strain, resulting in a natural non-planar geometry when prepared in the form of flat films. In this article, we analyze the influence of different molecular parameters of the monomers on the spontaneous shape of the polymeric films and their deformation under different stimuli, such as heating or light irradiation. Modifying the alkilic chains of the crosslinkers is a simple and highly effective way to increase the temperature sensitivity of the final actuator, while modifying ester orientation on the aromatic core interestingly acts on the bending direction. Combining such effects, we have demonstrated that LCN stripes made of different monomeric mixtures originate complex non-symmetric deformation under light activation, thus opening up new applications in photonic and robotics.
关键词： photonic actuators,liquid crystalline networks,curvature design,photoresponsive polymers,shape-changing materials
更新于2025-11-21 11:24:58
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High-density Azobenzene Side Chain Polymer Brush for Azimuthal and Zenithal Orientation Photoswitching of Nematic Liquid Crystal
摘要： The azimuthal and zenithal orientation switching of nematic liquid crystals (NLCs) can be performed by photoresponsive azobenzene alignment layers called command surfaces. Such photoresponsive layers have been prepared by molecular assembly methods or spincast of polymer materials. This work reports on the photo-switching orientation behavior of NLC on a high-density brush of an azobenzene-containing side chain liquid crystalline polymer. On the high-density polymer brush surface, the zenithal homeotropic/planar photoalignment switching modes triggered by UV/visible light irradiation are reversed from those observed for traditional command surface systems, reflecting the azobenzene side chain orientation directing parallel with the substrate surface. Because the thermally stable trans-azobenzene provides the in-plane orientation of NLC, irradiation with linearly polarized visible light readily switches the azimuthal direction to an arbitrary direction, and the resulting orientation is retained persistently. This paper discusses the features of the architecture of high-density polymer brush as the command surface for NLC orientation.
关键词： azobenzene,photoalignment,photoresponsive surface,nematic liquid crystal,polymer brush
更新于2025-09-23 15:23:52
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Performance improvement in photosensitive organic field effect transistor by using multi-layer structure
摘要： In this study, a new approach was introduced for Photo-OFETs as a multi-layer structure. Poly(3-hexylthiophene-2,5-diyl) regioregular (P3HT) and Copper(II) phthalocyanine (CuPc) thin films were used as two different active photo-absorber layers in the same device structure. Poly(methyl methacrylate) (PMMA) was used as a dielectric layer and all devices were fabricated with a top-gate bottom-contact configuration. In order to investigate the effect of the location of each layer on the Photoresponsive organic field-effect transistors (Photo-OFET) performance, five different devices in various structures were produced and analyzed. Surface properties of active layers have been investigated via Atomic Force Microscopy (AFM) and effects of surface roughness on device performance have been discussed. P3HT/CuPc/P3HT multi-layered structure exhibited the best performance in terms of photoresposivity(as 45 mA/W) and photosensitivity (~ 2x103). Photo-OFET based on a multi-layer structure demonstrated superior performance with wider absorbance spectrum region compared to conventional single component devices of P3HT or CuPc. The proposed multi-layer structure can be a model to improve the realization of high performance Photo-OFETs.
关键词： Photoresponsive organic field-effect transistors,Organic field effect transistors,Multilayer structure,Poly(3-hexylthiophene),Photosensitivity,Poly(methyl methacrylate)
更新于2025-09-23 15:23:52
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Photoresponsive Halogen-Bonded Liquid Crystals: The Role of Aromatic Fluorine Substitution
摘要： A new strategy for controlling the liquid crystalline and photophysical properties of supramolecular mesogens assembled via halogen bonding is reported. Changing the degree of fluorination at the halogen-bond donor of the supramolecular liquid crystal allows for the fine-tuning of the halogen bond strength and thereby provides control over the temperature range of the mesophase. At least three fluorine atoms have to be present to ensure efficient polarization of the halogen-bond donor and the formation of a mesophase. In addition, it was found that stilbazole acceptors are superior to their azopyridine counterparts in promoting stable liquid crystalline phases. The halogen-bond-driven supramolecular liquid crystals between fluorinated azobenzenes and stilbazole/azopyridine acceptors show a rich variety of photoinduced processes driven by azobenzene photoisomerization, dictated not only by the photochemical properties of the molecular components but also by the difference between the operation temperature and the clearing point.
关键词： photoresponsive materials,fluorination,supramolecular chemistry,azobenzenes,halogen bonding,liquid crystals
更新于2025-09-23 15:23:52
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Optically Responsive, Smart Anti-Bacterial Coatings via the Photofluidization of Azobenzenes
摘要： Antibacterial strategies sans antibiotic drugs have recently garnered much interest as a mechanism by which to inhibit biofilm formation and growth on surfaces due to the rise of antibiotic-resistant bacteria. Based on the photofluidization of azobenzenes, we demonstrate for the first time the ability achieve up to a 4 log reduction in bacterial biofilms by opto-mechanically activating the disruption and dispersion of biofilms. This unique strategy with which to enable biofilm removal offers a novel paradigm with which to combat antibiotic resistance.
关键词： photofluidization,azobenzenes,photoresponsive polymers,antibacterial and antifouling strategies,optically responsive materials,antibacterial coatings,smart materials
更新于2025-09-23 15:23:52
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Photoresponsive Soft Materials Based on Reversible Proton Transfer
摘要： Proton transfer is one of the most fundamental processes in nature and numerous chemical, material, and biological processes are driven by proton transfer. For example, biological systems use proton gradient as an energy form to synthesize ATP for their biological functions; many organic reactions are catalyzed by Bronsted acids; and many materials have pH‐sensitive properties. Proton transfer is also involved in different aspects of polymer science relative to preparation, property, and processing. For example, cationic polymerizations can be initiated by proton transfer from a strong acid to a monomer. It has been reported that many polymers are sensitive to the pH (proton concentration) of the environment, and their properties including mechanical, geometrical, electric, optical, and magnetic properties, change with pH due to proton transfer between the polymers and the environment. Polymers with acid‐labile bonds have been studied for drug delivery; and photoinduced cationic polymerization using photoacid‐generators (PAGs) has been applied to photolithography.
关键词： Proton transfer,photoacid,fragrant‐releasing polymers,photoresponsive nanoparticles,photochromic materials,photoresponsive polymers,reversible
更新于2025-09-23 15:21:01
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Optoregulated biointerfaces to trigger cellular responses
摘要： Optoregulated biointerfaces offer the possibility to manipulate the interactions between cell membrane receptors and the extracellular space. This Feature Article summarizes recent efforts of our group and others during the last decade in the development of light-responsive biointerfaces to stimulate cells and elicit cellular responses using photocleavable protecting groups (PPG) as working tool. This article begins by providing a brief introduction to available PPGs, with a special focus on the widely used o-nitrobenzyl family, followed by an overview of molecular design principles for the control of bioactivity in the context of cell-materials interactions, and the characterization methods to follow the photoreaction at surfaces. We present various light guided cellular processes using PPGs, including cell adhesion, release, migration, proliferation and differentiation, in vitro and in vivo. Finally, this feature article closes with our perspective view on the current status and future challenges of this topic.
关键词： cell-materials interactions,photoresponsive biomaterials,phototriggers,light-guided cells
更新于2025-09-23 15:21:01
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Central-to-Helical-to-Axial-to-Central Transfer of Chirality with a Photoresponsive Catalyst
摘要： Recent advances in molecular design have displayed striking examples of dynamic chirality transfer between various elements of chirality, e.g. from central to either helical or axial chirality and vice versa. While considerable progress in atroposelective synthesis has been made, it is intriguing to design chiral molecular switches able to provide selective and dynamic control of axial chirality with an external stimulus to modulate stereochemical functions. Here, we report the synthesis and characterization of a photoresponsive bis(2-phenol)-substituted molecular switch 1. The unique design exhibits a dynamic hybrid central-helical-axial transfer of chirality. The change of preferential axial chirality in the biaryl motif is coupled to the reversible switching of helicity of the overcrowded alkene core, dictated by the fixed stereogenic center. The potential for dynamic control of axial chirality was demonstrated by using (R)-1 as switchable catalyst to direct the stereochemical outcome of the catalytic enantioselective addition of diethylzinc to aromatic aldehydes, with successful reversal of enantioselectivity for several substrates.
关键词： atropisomers,photoresponsive catalyst,chirality transfer,photoisomerization,dynamic selectivity control,molecular switches
更新于2025-09-23 15:21:01
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || A Photoresponsive Multi-Bilayered Film for a Tunable Photonic Crystal
摘要： Over the last half‐century, advances in science based on the evolution of semiconductor physics and transistor electronics have greatly influenced the development of our lives. The key to this was the ability to design crystalline materials that tailor the conduction properties of electrons to suit diverse applications. More recently, the optical communication revolution has shifted the frontier in high‐speed, multiplex, and wide‐bandwidth information processing from electrons to photons, a shift that demands a new kind of synthetic soft material to mold the gigabits. To address this need, recent research has suggested a way to tailor the propagation of light much like that of electrons, via the creation of periodic optical media dubbed photonic crystals (PCs).
关键词： azobenzene,photonic crystals,multi‐bilayered film,photoresponsive,tunable
更新于2025-09-23 15:21:01
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Photoresponsive Supramolecular Polymers
摘要： According to the definition by Meijer and coworkers in their seminal review [1], supramolecular polymers are polymeric assemblies of small molecular units that are brought together through reversible and directional noncovalent interactions, leading to polymeric properties in solution and bulk states [1–5]. Owing to the reversible nature of their main‐chain formation, supramolecular polymers have attracted considerable attention as highly stimuli‐responsive polymeric materials compared to conventional polymer counterparts. Needless to say, supramolecular polymers have high responsiveness in terms of “degree of polymerization” to temperature change mainly due to entropic reasons, and to solvent media mainly due to enthalpic reasons. Such high responsiveness to external environment has enabled not only the exploration of temperature‐ and solvent‐dependent supramolecular polymer systems, but also the analyses of the supramolecular polymerization process regulated by these parameters [6]. From a technical viewpoint, furthermore, supramolecular polymers have another advantage over conventional polymers, i.e. quite ambient polymerization conditions without using any chemical reagents. This allows more flexible monomer design and enables introduction of a wide variety of functional molecules into supramolecular monomers.
关键词： stimuli-responsive,photoresponsive,supramolecular polymers,polymerization,noncovalent interactions
更新于2025-09-23 15:21:01