Influence of thickness and strength on plastic instability in tailored steel structures.

A mathematical model was intricately devised to explore the influence of continuous variations in thickness and mechanical properties on the performance of tailor rolled blanks (TRB) and tailor rolled tubes (TRT). Through the integration of analytical and numerical techniques, it was discerned that these variations play a pivotal role in modulating stress distribution and strain localization, thereby inducing a spectrum of plastic instability behaviors within the structures. The introduction of an 'equivalent strength' metric as a novel means to quantify structural performance shed light on strategic material distribution to enhance durability and mechanical efficiency. Moreover, the insights garnered from this research deepen the understanding of the mechanical responses of tailor-rolled constructs under varying loads, offering valuable perspectives for the development and fabrication of engineered materials with bespoke properties. This study not only contributes to bridging a knowledge gap in the realm of tailored material engineering but also fosters the advancement of design methodologies in the construction of high-performance engineered structures.

Photodeformable Azo Polymer Janus Particles Obtained upon Nonsolvent-Induced Phase Separation and Asynchronous Aggregation.

Photodeformable submicron Janus particles (JPs), containing an epoxy-based azo polymer (BP-AZ-CN) and poly(methyl methacrylate) (PMMA), were fabricated upon nonsolvent-induced phase separation. The formation of the JPs was induced by gradually adding deionized water into a tetrahydrofuran (THF) solution of both polymers. The results show that the two polymers start to precipitate from the solution at almost the same water content and immediately separate into two phases in each particle due to the strong incompatibility between the two components. After the nucleation, the sizes of the aggregates increase with increasing water content in the following growth stage. The amount of BP-AZ-CN molecules assembling into the aggregates is controlled by the water content in the medium, while the aggregation of PMMA molecules is a slow diffusion-controlled process due to the much higher molecular weight of this polymer. With a further increase in the water content in the dispersion medium, the swollen aggregates collapse to form JPs. Interestingly, when a dispersion with a water content of 50 vol % is diluted with a THF/H2O mixture with the same water content, the shapes of the JPs are significantly modified and vitrified after removal of THF through evaporation. By increasing the dilution multiples adopted to dilute the intermediate dispersions, JPs with more asymmetric shapes are obtained due to the enhanced asynchronous aggregation. Ternary phase diagrams calculated according to the Flory-Huggins theory provide a semi-quantitative description and rationalization of the phase separation behavior related to the thermodynamic factors. The differences in the transport behavior and aggregation dynamics of the two polymers are also proven to be critical for the formation of the asymmetric structures. Upon irradiation, the BP-AZ-CN compartments of JPs exhibit remarkable elongation along the electric vibrational direction of a linearly polarized laser beam at a wavelength of 488 nm.

Compartmentalized Janus droplets of photoresponsive cholesteric liquid crystals and poly(dimethylsiloxane)-based oligomers.

A new kind of Janus droplet containing photoresponsive cholesteric liquid crystals (CLCs) was fabricated for the first time and their formation, compartment structure, mesophase texture and function were thoroughly investigated. In the droplets, the CLC compartments included a typical nematic LC (4'-pentyl-4-biphenylcarbonitrile) doped with an azobenzene-containing chiral dopant, and the other compartments were formed of a poly(dimethylsiloxane)-based oligomer. Janus droplets were fabricated through microphase separation of the incompatible components in chloroform solution dispersed in an aqueous medium, induced by slow evaporation of chloroform. The mesophase structures of the CLC phase in Janus droplets, both suspended in aqueous medium and spreading on substrates, were controlled by the bulk elastic free energy of the CLC phase, surface anchoring and confining geometries. The helix pitch of the cholesteric phase in the droplets was determined by the doping concentration of the chiral dopant. For the suspended Janus droplets with the helix pitch obviously smaller than the droplet sizes, the CLC compartments mainly possessed a bipolar structure instead of the Frank-Pryce structure typically observed on CLC droplets. After the Janus droplets spread on the substrates, the CLC compartments changed to crescent shapes due to the different wettability characteristics of the two compartments, and the formed stable and metastable CLC configurations were distinctively different from those in the suspensions. Interestingly, when the Janus droplets spreading on substrates were irradiated with a laser beam (λ = 488 nm) of low intensity, the directors in the CLC compartments rearranged to form fingerprint structures with minimum total energy.

Triphasic Polymer Particles Assembled via Microphase Separation with Multiple Functions.

This work investigated a unique type of triphasic colloidal particles composed of an azo polymer (PCNAZO), a fluorescent pyrene-containing polymer [P(MMA-co-PyMA)], and a poly(dimethylsiloxane)-based polymer (H2pdca-PDMS), focusing on the synthesis, forming mechanism, morphology control, and functions. The triphasic particles with well-defined morphologies were assembled through the microphase separation of the components in dichloromethane (DCM) droplets in an aqueous medium, induced by the gradual evaporation of the organic solvent. The real-time fluorescence emission spectra of the pyrenyl moieties and in situ microscopic observations show that the formation of the triphasic particles undergoes the segregation of the PCNAZO-rich phase, separation between P(MMA-co-PyMA)-rich and H2pdca-PDMS-rich phases, coalescence, and solidification in the dispersed droplets. The structure formation is due to the strong phase separation of the polymers as revealed by the calculations based on the Flory-Huggins theory. The morphologies and phase boundaries of the particles are found to be controlled by the interfacial energy between the phases and processing conditions. The triphasic particles thus obtained possess a series of interesting functions stemming from the polymers and the triple-compartmentalized structures. After being deposited on a substrate, the H2pdca-PDMS parts can tightly adhere on the surface, caused by the spreading nature of the polymer when slightly swelled by DCM. Upon irradiation with a linearly polarized laser beam at 488 nm, the azo polymer compartments show a significant elongation along the electric vibration direction of the polarized light, accompanied by the cooperative deformation of the H2pdca-PDMS pads. When dispersed in water and adhered on the substrate surface, the triphasic particles exhibit tunable colors originating from the fluorescence of the pyrenyl fluorophores and light absorption of the azo chromophores. The real-time investigation methods developed here could lead to the deep understanding of the structure formation process in the confined volume and be applied in phase-separation study of other polymers as well.

Topographical transition of submicron pillar array of azo molecular glass induced by circularly polarized light.

The well-aligned submicron patterns on surfaces have attracted wide attention from scientific curiosity to practical applications. Understanding their formation and transition is highly desirable for efficient manufacture of the patterns for many usages. Here, we report a unique observation on self-organized topographical transition of submicron pillar array of an azo molecular glass, induced by irradiation with circularly polarized light. During gradual erasure of the patterns upon exposure to the light, which is a property of this material, a new set of pillars unexpectedly emerge with new one in middle of each triangle cell of the original array. The highly regular pillar array with triple area density is formed and finally stabilized in the process, as revealed by thorough investigation reported here. This unusual observation and its rationalization will be of benefit for deep understanding of the light-matter interaction and can be expected to be applied in different areas.

Comparative study of photoinduced surface-relief-gratings on azo polymer and azo molecular glass films.

Photoinduced surface-relief-gratings (SRGs) on azo polymer and azo molecular glass films, caused by trans-cis isomerization of azo chromophores, have attracted wide interest for their intriguing nature and many possible applications in recent years. Understanding the mechanical properties of SRGs at the nanoscale is critically important for elucidating their formation mechanism and exploring their applications. In this work, a representative azo polymer (BP-AZ-CA) and a typical azo molecular glass (IAC-4) were comparatively studied for the first time concerning their properties related to SRG formation through a variety of methods. The results indicate that when inscribing SRGs on the films, IAC-4 shows a much higher efficiency for forming SRGs relative to that of BP-AZ-CA. The overall average moduli of SRGs measured by nanomechanical mapping techniques are obviously smaller compared with the moduli of the corresponding films of both materials. The moduli at different regions of SRGs are periodically varied along the grating vector direction for both BP-AZ-CA and IAC-4 gratings. The moduli at the trough regions of SRGs are always larger than those of the crests, while the moduli at the hillsides are the smallest. Distinct from BP-AZ-CA, even the moduli at the trough regions of IAC-4 SRG are smaller compared with that of the original film, and the ratio between the trough and crest moduli is significantly larger for IAC-4. These results provide deep understanding of the SRG formation mechanism and reveal the clear distinction between these two types of glassy materials for their SRG-forming behavior, which are important for future applications.

Directional mass transfer of azo molecular glass microsphere induced by polarized light in aqueous immersion media.

Photoinduced mass transfer of azo polymer and azo molecular glass has been intensively investigated under various light irradiation conditions simply using air as the ambient environment. In this work, in order to understand the effects of the surrounding medium on the light-induced process, azo molecular glass microspheres adhered on a substrate were immersed in water and different aqueous solutions, and their mass transfer behavior was investigated by irradiation with linearly polarized light. The microspheres in the aqueous media showed significant deformation through directional mass transfer upon light irradiation and transformed into a series of shape-anisotropic particles as revealed by microscopic observations. Compared with their counterparts upon light irradiation in air, the particles immersed in the aqueous media exhibited larger elongation parallel to the substrate and higher shape anisotropy. Optical simulation showed that this was caused by the alteration of the direction of the electric vibration of the refracted light at the medium-microsphere interface, which controlled the mass transfer behavior. On the other hand, the viscosity of the aqueous media showed no effect on the mass transfer process induced by the irradiation. The photo-thermal effect on the mass transfer behavior was ruled out as the thermal dissipation through a liquid is much more efficient than that through air. On the basis of this, this methodology was also successfully employed in the photo-fabrication of anisotropic submicron-sized periodic structures in aqueous medium. These observations can supply deep understanding of this fascinating process induced by polarized light and extend the scope of its applications.

Mussel-like Surface Adhesion and Photoinduced Cooperative Deformation of Janus Particles.

This study focused on mussel-like surface adhesion and photoinduced cooperative deformation of a unique type of Janus particles (JPs), composed of an isosorbide-based molecular glass bearing push-pull type azo chromophore (IAC-4) and a 2,6-pyridinedicarboxamide-containing poly(dimethylsiloxane) oligomer (H2pdca-PDMS). The JPs were obtained by the solvent evaporation method in an aqueous medium with the dispersed phase of a solution of IAC-4 and H2pdca-PDMS in dichloromethane (DCM). The JP formation and its mechanism were investigated by electron microscopy, in situ optical microscopy, and theoretical analysis. The results showed that the Janus structures form through gradual segregation between the two components in the droplets induced by the evaporation of DCM, which follows the ternary phase diagrams calculated according to Flory-Huggins theory. In the following stage, the gradual coalescence of small domains in droplets is controlled by dynamic factors. After being deposited on a substrate, the JPs exhibit unidirectional adhesion with the H2pdca-PDMS parts spreading on the substrate, while the IAC-4 parts orientate away from the substrate. The mussel-like adhesion is caused by the interfacial interaction of H2pdca-PDMS with the hard surfaces (i.e., glass and silicon substrates) and its strong ability to spread and wet the surfaces to increase the contact area with the surfaces. Upon irradiation with linearly and circularly polarized laser beams at 488 nm, respectively, a series of unique surface morphologies are observed because of the photoinduced deformation of the IAC-4 parts along the electric vibration direction of the polarized light and the cooperative deformation of the H2pdca-PDMS parts of the JPs. The cooperative deformation reveals the strong interfacial interaction and cohesiveness between the IAC-4 and the H2pdca-PDMS phases in JPs. No peeling-off from the substrate is observed after the large-scale deformation, which also indicates the strong adhesion of the JPs on the substrate surfaces. This study not only demonstrates the mussel-like adhesion and unique cooperative deformation behavior but also supplies new insights into the interfacial interaction in JPs as well as that with hard surfaces, thus opening a new avenue for surface modification and functionalization.

Photoinduced mass transfer of azo polymers from micrometer to submillimeter studied by a real-time single particle strategy.

Photoinduced mass transfer of azo polymers is a fascinating function with potential applications in areas ranging from photonics and nanofabrication to cell biology. However, the true nature of this unique effect still remains elusive in many aspects due to its puzzling mechanism and lack of a way for real-time observation. This work presents a new strategy to study the photoinduced mass transfer through in situ optical microscopic observation and videoing on single particles under laser irradiation. By inspecting the shape evolution processes of the particles from the side view, both the scale and direction of the mass transfer can be well characterized in a real-time manner, which shows great advantages for carrying out the systematic investigation. The mass transfer behaviour was thus investigated using the microspheres with diameters (D) ranging from micrometer to submillimeter. The mass transfer in the direction of the electric vibration was observed to occur in different scales for azo polymers with different degrees of functionalization (DFs) controlled by the light penetration depths. With the varied combinations of particle sizes and DFs, the particles with diversified shape-anisotropy and complex morphologies were generated by the mass transfer. For the microspheres with sizes in micrometer and submillimeter scales, those formed from the azo polymers with extremely high DF (100%) and extremely low DF (1%) respectively exhibited the most efficient mass transfer to cause significant shape deformations. With the optical and thermal simulations, these observations are well rationalized by considering the optical power distribution, energy utilization efficiency and heat dissipation route. This study not only provides deep insight into the photoinduced mass transfer behavior, but also extends the mass transfer scale of the particles from micrometer to submillimeter for the first time.

Producing "Symbiotic" Reduced Graphene Oxide/Mn3O4 Nanocomposites Directly from Converting Graphite for High-Performance Supercapacitor Electrodes.

Almost all existing methods for preparing reduced graphene oxide/Mn3O4 (RGO/Mn3O4) composites are based on the synthetized graphene or graphene oxides (GO), which make them complicated and high-cost processes. Here, we reported a new method, which is able to convert graphite directly to RGO/Mn3O4 composites. Thus, it is simpler, more economical, and productive. The structure of RGO/Mn3O4 inheriting intermediate product GO/MnO2 composites that are formed by the present method is a novel three-dimensional "multilayer steamed bread" nanostructure, which constitutes mutually beneficial "symbiosis". The nano-Mn3O4 supports the space between RGO layers and further to the combination of RGO to self-assemble into large-sized (>40 µm) nanocomposites. Meanwhile, the formed Mn3O4 particles were small (60 × 10 nm2) in diameter and distributed homogeneously without the use of any template and surfactant. Because the structure and nanosize of composite cause the excellent electrochemical properties, RGO/Mn3O4 electrodes deliver an enhanced specific capacitance of 438.7 F/g at 0.3 A/g and outstanding cyclic stability (77.5% of its initial capacitance is retained after 1000 cycles).

Multifunctional Janus Particles Composed of Azo Polymer and Pyrene-Containing Polymer.

This study investigated Janus particles (JPs) composed of an azo polymer and a pyrene-containing polymer, focusing on preparation, formation mechanism, photoinduced deformation behavior, and fluorescent properties as well as tunable colors of the dispersions. A methacrylate-based copolymer containing pyrenyl groups (P(MMA-co-PyMA)) and two azo polymers, i.e., a methacrylate-based polymer (PCNAZO) and an epoxy-based polymer (CH-TZ-NT) both bearing push-pull-type azo chromophores, were synthesized for this purpose. Two types of Janus particles, P(MMA-co-PyMA)/PCNAZO JPs and P(MMA-co-PyMA)/CH-TZ-NT JPs, were fabricated through microphase separation of the components in the droplets dispersed in aqueous media, induced by the evaporation of the organic solvent. The process of JP formation was thoroughly investigated by exploiting the function of pyrene moieties as a molecular probe through measuring the fluorescence emission spectra at different times during the structure evolution. The photoluminescent (PL) intensity, excimer emission, and vibrational fine structure of the fluorescence spectra were observed to give information about phase separation and solidification occurred in the dispersed droplets. The observations were rationalized by analysis with ternary phase diagrams calculated on the basis of the Flory-Huggins theory. Upon irradiation with a linearly polarized laser beam at 488 nm, the azo polymer parts in the P(MMA-co-PyMA)/PCNAZO JPs were observed to be elongated along the electric vibration direction of the polarized light and transformed into particles with unique morphologies. The dispersions of JPs with different compositions of the two types of the polymers showed highly tunable color changes originating from both fluorescence of the pyrenyl fluorophores and light absorption of the azo chromophores.

Superhydrophobic lotus-leaf-like surface made from reduced graphene oxide through soft-lithographic duplication.

In this work, reduced graphene oxide (RGO) was used as a material to fabricate superhydrophobic lotus-leaf-like surfaces through soft-lithographic duplication. In the process, a polydimethylsiloxane (PDMS) stamp was prepared by replica molding against the surfaces of fresh lotus leaves that functioned as masters. A dispersion of octadecylamine-modified reduced graphene oxide (ODA-RGO) in tetrahydrofuran (THF) was used as "ink". The lotus-leaf-like surfaces were fabricated by microcontact printing on the solid substrates. The results showed that due to the good processibility of the ODA-RGO dispersion, the printed layers display papillary micro/nano-structures with high fidelity to the surfaces of lotus leaves. The RGO-based lotus-leaf-like surfaces possess superhydrophobic characteristics with a water contact angle larger than 160° and the contact angle hysteresis less than 5°. Due to the excellent chemical stability of the RGO sheets, as-prepared surfaces show remarkable superhydrophobic stability. The lotus-leaf-like surfaces maintain the superhydrophobicity after heating treatment at 150 °C for 24 h or being exposed to corrosive solutions with different pH values for 12 h. The present findings prove that the RGO-based material is an ideal candidate for fabrication of environment-durable lotus-leaf-like surfaces, which can be expected to have applications in different areas.

Asymmetric Morphology Transformation of Azo Molecular Glass Microspheres Induced by Polarized Light.

In this work, photoinduced asymmetric morphology transformation of a type of azo molecular glass microspheres was thoroughly investigated to understand the effects of controlling factors on the process, related mechanism and unique functions. The monodispersed microspheres with their sizes over ten microns were fabricated from an isosorbide-based azo compound (IAC-4) by microfluidics. Under irradiation with linearly polarized light, the ten-micron-scale microspheres were transformed into three-dimensional (3D) asymmetric particles through directional mass transfer. Microscopic observations and optics simulation were employed to investigate the morphology transformations. The results show that the penetration depth of light at different wavelengths plays an extremely important role to affect the asymmetric deformation behavior of the IAC-4 microspheres, which determines deformation region, deformation degree and final shapes of the particles. The light intensity (50-200 mW/cm2) is a less important factor, while the deformation rate of the light-penetrated part linearly increases with the intensity. When the light intensity varies in this range, the deformation degree and the final asymmetric morphology are determined by exposure energy (light intensity × irradiation time). The IAC-4 microspheres with different sizes show distinct morphology transformation behavior and the deformed particles possess different shapes, caused by the variation of volume fraction of the light-penetrated part in the microspheres. The increase in the ratio of the light-penetrated part to the total volume of the microspheres results in larger scale deformations. Based on the above understanding, asymmetric particles with various morphologies can be fabricated through a precisely controllable way. The asymmetric particles loaded on various surfaces show ability to render remarkable wetting anisotropy of water droplets on the substrates.

A Dynamic Graphene Oxide Network Enables Spray Printing of Colloidal Gels for High-Performance Micro-Supercapacitors.

Properly controlling the rheological properties of nanoparticle inks is crucial to their printability. Here, it is reported that colloidal gels containing a dynamic network of graphene oxide (GO) sheets can display unusual rheological properties after high-rate shearing. When mixed with polyaniline nanofiber dispersions, the GO network not only facilitates the gelation process but also serves as an effective energy-transmission network to allow fast structural recovery after the gel is deformed by high-rate shearing. This extraordinary fast recovery phenomenon has made it possible to use the conventional air-brush spray technique to print the gel with high-throughput and high fidelity on nonplanar flexible surfaces. The as-printed micro-supercapacitors exhibit an areal capacitance 4-6 times higher than traditionally spray-printed ones. This work highlights the hidden potential of 2D materials as functional yet highly efficient rheological enhancers to facilitate industrial processing of nanomaterial-based devices.

Azopyridine-Containing Three-arm Star Compounds with Aggregation-induced Fluorescence.

Three-arm star azopyridinium salts self-organize into various morphologies in water/organic mixed solvents. Interesting AIE and self-assembling features are observed due to the strong interaction of the azopyridinium moieties with the highly polar H2 O molecules causing the salts to aggregate, which restricts the molecular motion and induces the fluorescence.

Shaping monodispersed azo molecular glass microspheres using polarized light.

Azo molecular glass (IAC-4) microspheres with a monodispersed diameter over ten microns were fabricated by microfluidics and unique shape manipulation was achieved based on their fascinating photoinduced deformation behaviour. After irradiation with a polarized laser beam (λ = 488 nm), the IAC-4 microspheres were transformed into uniform mushroom-like particles, and their three-dimensional (3D) asymmetric shapes were precisely manipulated by adjusting the irradiation time and the polarization state of light. By observing the particle morphology in three orthogonal views (top view, front view and side view) by scanning electron microscopy (SEM), the photoinduced deformation behaviour of the ten-micron-sized particles was comprehensively revealed in the 3D space for the first time. It was observed that the photoinduced deformation asymmetrically occurred on the upper part of the microspheres due to the strong optical absorption of the azo chromophores. Besides, the deformation manner of the upper part was decided by the direction of the electric vibration of the refracted light. This work not only depicts a clear picture of the photoinduced deformation behaviour of the ten-micron-sized azo particles upon polarized light irradiation, but also provides a new method to controllably manipulate the particle shape from spheres to complex 3D architectures.

Rolling up graphene oxide sheets through solvent-induced self-assembly in dispersions.

Herein we report a new approach to fabricating nanoscrolls through the self-assembly of graphene oxide (GO) sheets in a dispersion. The assembly process for GO nanosheets was induced by the dropwise addition of an appropriate organic solvent such as N,N-dimethylformamide (DMF) into the aqueous dispersion. The results show that nanoscrolls were gradually formed from the GO sheets by rolling-up in a piece-by-piece manner with the increase of the DMF content. The transmission electron microscopic analysis indicates that for a typical case, the nanoscrolls have an average diameter of 242 ± 102 nm at the central part and the interlayer spacing between adjacent GO layers is 0.58 nm. The scrolls were estimated to have 207 turns and include on average 42 pieces of GO sheets per scroll. By this method, GO sheets with different sizes and oxidation degrees were proved to be able to form GO nanoscrolls in a similar way. Moreover, it is interesting that the diffraction efficiency of surface-relief-gratings photoinduced on the film of azo molecular glass was significantly enhanced by doping the GO nanoscrolls with a very low content (0.5 wt%); this suggests a possible new application for the GO scrolls in optical devices. This facile approach, which is also feasible by using other organic solvents such as ethanol, can be used to fabricate GO nanoscrolls for large scale applications in supercapacitors, sensors and other devices.

Janus and Strawberry-like Particles from Azo Molecular Glass and Polydimethylsiloxane Oligomer.

This study investigated Janus and strawberry-like particles composed of azo molecular glass and polydimethylsiloxane (PDMS) oligomer, focusing on controllable fabrication and formation mechanism of these unique structures and morphologies. Two materials, the azo molecular glass (IA-Chol) and PDMS oligomer (H2pdca-PDMS), were prepared for this purpose. The Janus and strawberry-like particles were obtained from the droplets of a dichloromethane (DCM) solution containing both IA-Chol and H2pdca-PDMS, dispersed in water and stabilized by poly(vinyl alcohol). Results show that the structured particles are formed through segregation between the two components induced by gradual evaporation of DCM from the droplets, which is controlled by adding ethylene glycol (EG) into the above dispersion. Without the addition of EG, Janus particles are formed through the full segregation of the two components in the droplets. On the other hand, with the existence of EG in the dispersion, strawberry-like particles instead of Janus particles are formed in the phase separation process. The diffusion of EG molecules from the dispersion medium into the droplets causes the PDMS phase deswelling in the interfacial area due to the poor solvent effect. Caused by the surface coagulation, the coalescence of the isolated IA-Chol domains is jammed in the shell region, which results in the formation of the strawberry-like particles. For the particles separated from the dispersion and dried, the PDMS oligomer phase of the Janus particles can adhere and spread on the substrate to form unique "particle-on-pad" morphology due to its low surface energy and swelling ability, while the strawberry-like particles exist as "standstill" objects on the substrates. Upon irradiation with a linearly polarized laser beam at 488 nm, the azo molecular glass parts in the particles are significantly deformed along the light polarization direction, which show unique and distinct morphologies for these two types of the particles.

Azo-Polymer Janus Particles Assembled by Solvent-Induced Microphase Separation and Their Photoresponsive Behavior.

We report the successful fabrication of photoresponsive Janus particles (JPs) composed of an epoxy-based azo polymer and poly(methyl methacrylate) (PMMA). Two representative azo polymers, of which one polymer (BP-AZ-CN) has cyano groups as electron-withdrawing substituents on the azobenzene moieties and the other polymer (BP-AZ-CA) has carboxyl groups as the electron-withdrawing substituents, were adopted for the investigation. The nanoscaled JPs, with a narrow size distribution and different azo polymer/PMMA ratios, were fabricated through self-assembly in solution and as dispersions. Upon irradiation with linearly polarized light (λ=488 nm), two types of photoresponsive behavior were observed for JPs in the solid state. For JPs composed of BP-AZ-CN and PMMA, the light irradiation caused the azo-polymer component to be stretched along the light polarization direction. Conversely, for JPs composed of BP-AZ-CA and PMMA, the azo-polymer component became separated from PMMA component under the same irradiation conditions. These observations are valuable for a deeper understanding of the nature of self-assembly and photoinduced mass-transport at the nanometer scale.

Azo Polymer Janus Particles Possessing Photodeformable and Magnetic-Field-Responsive Dual Functions.

It is of great fundamental and practical significance to endow Janus particles with various field-responsive properties. In this study, a new strategy with a wide range of application possibilities is developed to fabricate JPs composed of a methacrylate-based azo polymer, polystyrene, and Fe3 O4 nanoparticles. The JPs are obtained through microphase separation in a confined volume of the dispersed droplets. The azo polymer and PS are incorporated in JPs in a core-compartmentalized manner, and Fe3 O4 are proved to exist in the azo polymer phase. The JPs show responsive movement in the magnetic field and can be easily oriented with the help of the field. By variation of the intersection angle between the particle symmetrical axis and the polarization direction of the linearly polarized laser beam, different deformation modes are feasibly achieved for the JPs. By exploiting the dual-responsive properties, JPs with designed shapes can be fabricated by exposing the JPs to linearly polarized light.