Publications

2020
Phillips KR, Zhang CT, Yang T, Kay T, Gao C, Brandt S, Liu L, Yang H, Li Y, Aizenberg J, et al. Fabrication of Photonic Microbricks via Crack Engineering of Colloidal Crystals. Advanced Functional Materials. 2020;(30) :1908242. Publisher's VersionAbstract

Evaporation-induced self-assembly of colloidal particles is one of the most versatile fabrication routes to obtain large-area colloidal crystals; however, the formation of uncontrolled “drying cracks” due to gradual solvent evaporation represents a significant challenge of this process. While several methods are reported to minimize crack formation during evaporation-induced colloidal assembly, here an approach is reported to take advantage of the crack formation as a patterning tool to fabricate microscopic photonic structures with controlled sizes and geometries. This is achieved through a mechanistic understanding of the fracture behavior of three different types of opal structures, namely, direct opals (colloidal crystals with no matrix material), compound opals (colloidal crystals with matrix material), and inverse opals (matrix material templated by a sacrificial colloidal crystal). This work explains why, while direct and inverse opals tend to fracture along the expected {111} planes, the compound opals exhibit a different cracking behavior along the nonclose-packed {110} planes, which is facilitated by the formation of cleavage-like fracture surfaces. The discovered principles are utilized to fabricate photonic microbricks by programming the crack initiation at specific locations and by guiding propagation along predefined orientations during the self-assembly process, resulting in photonic microbricks with controlled sizes and geometries.

Marcella N, Liu Y, Timoshenko J, Guan E, Luneau M, Shirman T, Plonka AM, van der Hoeven JES, Aizenberg J, Friend C, et al. Neural network assisted analysis of bimetallic nanocatalysts using X-ray absorption near edge structure spectroscopy. Physical Chemistry Chemical Physics. 2020;(22) :18902-18910. Publisher's VersionAbstract

X-ray absorption spectroscopy is a common method for probing the local structure of nanocatalysts. One portion of the X-ray absorption spectrum, the X-ray absorption near edge structure (XANES) is a useful alternative to the commonly used extended X-ray absorption fine structure (EXAFS) for probing three-dimensional geometry around each type of atomic species, especially in those cases when the EXAFS data quality is limited by harsh reaction conditions and low metal loading. A methodology for quantitative determination of bimetallic architectures from their XANES spectra is currently lacking. We have developed a method, based on the artificial neural network, trained on ab initio site-specific XANES calculations, that enables accurate and rapid reconstruction of the structural descriptors (partial coordination numbers) from the experimental XANES data. We demonstrate the utility of this method on the example of a series of PdAu bimetallic nanoalloys. By validating the neural network-yielded metal–metal coordination numbers based on the XANES analysis by previous EXAFS characterization, we obtained new results for in situ restructuring of dilute (2.6 at% Pd in Au) PdAu nanoparticles, driven by their gas and temperature treatments.


 
Meeks A, Mac R, Chathanat S, Aizenberg J. Tunable Long-Range Interactions between Self-Trapped Beams driven by the Thermal Response of Photoresponsive Hydrogels. Chemistry of MaterialsChemistry of Materials. 2020. Publisher's Version
Paink GK, Kolle S, Le D, Weaver JC, Alvarenga J, Ahanotu O, Aizenberg J, Kim P. Dynamic Self-Repairing Hybrid Liquid-in-Solid Protective Barrier for Cementitious Materials. ACS Applied Materials & InterfacesACS Applied Materials & Interfaces. 2020;12 (28) :31922 - 31932. Publisher's VersionAbstract
Corrosion and surface fouling of structural materials, such as concrete, are persistent problems accelerating undesirable material degradation for many industries and infrastructures. To counteract these detrimental effects, protective coatings are frequently applied, but these solid-based coatings can degrade or become mechanically damaged over time. Such irreversible and irreparable damage on solid-based protective coatings expose underlying surfaces and bulk materials to adverse environmental stresses leading to subsequent fouling and degradation. We introduce a new concept of a hybrid liquid-in-solid protective barrier (LIB) to overcome the limitations of traditional protective coatings with broad applicability to structural materials. Through optimization of capillary forces and reduction of the interfacial energy between an upper mobile liquid and a lower immobile solid phase, a stable liquid-based protective layer is created. This provides a persistent self-repairing barrier against the infiltration of moisture and salt, in addition to omniphobic surface properties. As a model experimental test bed, we applied this concept to cementitious materials, which are commonly used as binders in concrete, and investigated how the mobile liquid phase embedded within a porous solid support contributes to the material’s barrier protection and antifouling properties. Using industry standard test methods for acid resistance, chloride-ion penetrability, freeze–thaw cyclability, and mechanical durability, we demonstrate that LIBs exhibit significantly reduced water absorption and ion penetrability, improved repellency against various nonaqueous liquids, and resistance to corrosion while maintaining their required mechanical performance as structural materials.Corrosion and surface fouling of structural materials, such as concrete, are persistent problems accelerating undesirable material degradation for many industries and infrastructures. To counteract these detrimental effects, protective coatings are frequently applied, but these solid-based coatings can degrade or become mechanically damaged over time. Such irreversible and irreparable damage on solid-based protective coatings expose underlying surfaces and bulk materials to adverse environmental stresses leading to subsequent fouling and degradation. We introduce a new concept of a hybrid liquid-in-solid protective barrier (LIB) to overcome the limitations of traditional protective coatings with broad applicability to structural materials. Through optimization of capillary forces and reduction of the interfacial energy between an upper mobile liquid and a lower immobile solid phase, a stable liquid-based protective layer is created. This provides a persistent self-repairing barrier against the infiltration of moisture and salt, in addition to omniphobic surface properties. As a model experimental test bed, we applied this concept to cementitious materials, which are commonly used as binders in concrete, and investigated how the mobile liquid phase embedded within a porous solid support contributes to the material’s barrier protection and antifouling properties. Using industry standard test methods for acid resistance, chloride-ion penetrability, freeze–thaw cyclability, and mechanical durability, we demonstrate that LIBs exhibit significantly reduced water absorption and ion penetrability, improved repellency against various nonaqueous liquids, and resistance to corrosion while maintaining their required mechanical performance as structural materials.
acsami.0c06357_final.pdf
Tesler AB, Sheng Z, Lv W, Fan Y, Fricke D, Park K-C, Alvarenga J, Aizenberg J, Hou X. Metallic Liquid Gating Membranes. ACS NanoACS Nano. 2020;14 (2) :2465 - 2474. Publisher's Version
Morim DR, Meeks A, Shastri A, Tran A, Shneidman AV, Yashin VV, Mahmood F, Balazs AC, Aizenberg J, Saravanamuttu K. Opto-chemo-mechanical transduction in photoresponsive gels elicits switchable self-trapped beams with remote interactions. Proceedings of the National Academy of Sciences. 2020;117 (8) :3953. Publisher's VersionAbstract
Self-trapped light beams hold potential for optical interconnects, applications in image transmission, rerouting light, logic gates for computing and, importantly, for the next-generation light-guiding-light signal processing, which envisions a circuitry-free and reconfigurable photonics powered by the dynamic interactions of self-trapped beams. In conventional nonlinear materials, however, self-trapping suffers from either the need for large incident beam powers and loss of beam interactions at large distances, or it is slow and irreversible. We show that rapidly and repeatably switchable self-trapped laser beams with remote communication capabilities can be elicited at exceptionally small intensities in a pliant, processable hydrogel functionalized with a chromophore. The ability to generate self-trapped beams with this unique set of properties offers unprecedented opportunities to develop light-guiding-light technologies.Next-generation photonics envisions circuitry-free, rapidly reconfigurable systems powered by solitonic beams of self-trapped light and their particlelike interactions. Progress, however, has been limited by the need for reversibly responsive materials that host such nonlinear optical waves. We find that repeatedly switchable self-trapped visible laser beams, which exhibit strong pairwise interactions, can be generated in a photoresponsive hydrogel. Through comprehensive experiments and simulations, we show that the unique nonlinear conditions arise when photoisomerization of spiropyran substituents in pH-responsive poly(acrylamide-co-acrylic acid) hydrogel transduces optical energy into mechanical deformation of the 3D cross-linked hydrogel matrix. A Gaussian beam self-traps when localized isomerization-induced contraction of the hydrogel and expulsion of water generates a transient waveguide, which entraps the optical field and suppresses divergence. The waveguide is erased and reformed within seconds when the optical field is sequentially removed and reintroduced, allowing the self-trapped beam to be rapidly and repeatedly switched on and off at remarkably low powers in the milliwatt regime. Furthermore, this opto-chemo-mechanical transduction of energy mediated by the 3D cross-linked hydrogel network facilitates pairwise interactions between self-trapped beams both in the short range where there is significant overlap of their optical fields, and even in the long range––over separation distances of up to 10 times the beam width––where such overlap is negligible.
Zhang CT, Liu Y, Wang X, Wang X, Kolle S, Balazs AC, Aizenberg J. Patterning non-equilibrium morphologies in stimuli-responsive gels through topographical confinement. Soft Matter. 2020;16 (6) :1463 - 1472. Publisher's VersionAbstract
Stimuli-responsive “smart” polymers have generated significant interest for introducing dynamic control into the properties of antifouling coatings, smart membranes, switchable adhesives and cell manipulation substrates. Switchable surface morphologies formed by confining stimuli-responsive gels to topographically structured substrates have shown potential for a variety of interfacial applications. Beyond patterning the equilibrium swelling behavior of gels, subjecting stimuli-responsive gels to topographical confinement could also introduce spatial gradients in the various timescales associated with gel deformation, giving rise to novel non-equilibrium morphologies. Here we show how by curing poly(N-isopropylacrylamide) (pNIPAAm)-based gel under confinement to a rigid, bumpy substrate, we can not only induce the surface curvature to invert with temperature, but also program the transient, non-equilibrium morphologies that emerge during the inversion process through changing the heating path. Finite element simulations show that the emergence of these transient morphologies is correlated with confinement-induced gradients in polymer concentration and position-dependent hydrostatic pressure within the gel. To illustrate the relevance of such morphologies in interfacial applications, we show how they enable us to control the gravity-induced assembly of colloidal particles and microalgae. Finally, we show how more complex arrangements in particle assembly can be created through controlling the thickness of the temperature-responsive gel over the bumps. Patterning stimuli-responsive gels on topographically-structured surfaces not only enables switching between two invertible topographies, but could also create opportunities for stimuli ramp-dependent control over the local curvature of the surface and emergence of unique transient morphologies. Harnessing these features could have potential in the design of multifunctional, actuatable materials for switchable adhesion, antifouling, cell manipulation, and liquid and particle transport surfaces.
Davidson EC, Kotikian A, Li S, Aizenberg J, Lewis JA. 3D Printable and Reconfigurable Liquid Crystal Elastomers with Light-Induced Shape Memory via Dynamic Bond Exchange. Advanced MaterialsAdvanced MaterialsAdv. Mater. 2020;32 (1) :1905682. Publisher's VersionAbstract
Abstract 3D printable and reconfigurable liquid crystal elastomers (LCEs) that reversibly shape-morph when cycled above and below their nematic-to-isotropic transition temperature (TNI) are created, whose actuated shape can be locked-in via high-temperature UV exposure. By synthesizing LCE-based inks with light-triggerable dynamic bonds, printing can be harnessed to locally program their director alignment and UV light can be used to enable controlled network reconfiguration without requiring an imposed mechanical field. Using this integrated approach, 3D LCEs are constructed in both monolithic and heterogenous layouts that exhibit complex shape changes, and whose transformed shapes could be locked-in on demand.
Guan E, Foucher AC, Marcella N, Shirman T, Luneau M, Head AR, Verbart DMA, Aizenberg J, Friend CM, Stacchiola D, et al. New Role of Pd Hydride as a Sensor of Surface Pd Distributions in Pd−Au Catalysts. ChemCatChemChemCatChemChemCatChem. 2020;12 (3) :717 - 721. Publisher's VersionAbstract
Abstract Isolated or contiguous, the surface distributions of Pd atoms in the Pd?Au bimetallic nanoparticle (NP) catalysts often influence activity and selectivity towards specific reactions. In this study, we used a concomitant Pd hydride formation upon H2 exposure as a probe of presence of contiguous Pd regions in bimetallic NPs. For demonstrating this method, we prepared silica supported monometallic Pd and bimetallic Pd?Au NPs with a Pd/Au ratio of 25/75 (Pd25Au75) and used X-ray absorption spectroscopy, scanning transmission electron microscopy and infrared spectroscopy to detect and quantitatively analyze the Pd hydride regions. This work provides a new approach to characterizing intra-particle heterogeneities within the bimetallic NPs at ambient temperature and pressure.
Waters JT, Li S, Yao Y, Lerch MM, Aizenberg M, Aizenberg J, Balazs AC. Twist again: Dynamically and reversibly controllable chirality in liquid crystalline elastomer microposts. Science Advances. 2020;6 (13) :eaay5349. Publisher's VersionAbstract
Photoresponsive liquid crystalline elastomers (LCEs) constitute ideal actuators for soft robots because their light-induced macroscopic shape changes can be harnessed to perform specific articulated motions. Conventional LCEs, however, do not typically exhibit complex modes of bending and twisting necessary to perform sophisticated maneuvers. Here, we model LCE microposts encompassing side-chain mesogens oriented along a magnetically programmed nematic director, and azobenzene cross-linkers, which determine the deformations of illuminated posts. On altering the nematic director orientation from vertical to horizontal, the post’s bending respectively changes from light-seeking to light-avoiding. Moreover, both modeling and subsequent experiments show that with the director tilted at 45°, the initially achiral post reversibly twists into a right- or left-handed chiral structure, controlled by the angle of incident light. We exploit this photoinduced chirality to design “chimera” posts (encompassing two regions with distinct director orientations) that exhibit simultaneous bending and twisting, mimicking motions exhibited by the human musculoskeletal system.
Lerch MM, Grinthal A, Aizenberg J. Viewpoint: Homeostasis as Inspiration—Toward Interactive Materials. Advanced MaterialsAdvanced MaterialsAdv. Mater. 2020;32 (20) :1905554. Publisher's VersionAbstract
Abstract Homeostatic systems combine an ability to maintain integrity over time with an incredible capacity for interactive behavior. Fundamental to such systems are building blocks of ?mini-homeostasis?: feedback loops in which one component responds to a stimulus and another opposes the response, pushing the module to restore its original configuration. Particularly when they cross time and length scales, perturbation of these loops by external changes can generate diverse and complex phenomena. Here, it is proposed that by recognizing and implementing mini-homeostatic modules?often composed of very different physical and chemical processes?into synthetic materials, numerous interactive behaviors can be obtained, opening avenues for designing multifunctional materials. How a variety of controlled, nontrivial material responses can be evoked from even simple versions of such synthetic feedback modules is illustrated. Moreover, random events causing seemingly random responses give insights into how one can further explore, understand and control the full interaction space. Ultimately, material fabrication and exploration of interactivity become inseparable in the rational design of such materials. Homeostasis provides a lens through which one can learn how to combine and perturb coupled processes across time and length scales to conjure up exciting behaviors for new materials that are both robust and interactive.
Yu Y, Brandt S, Nicolas NJ, Aizenberg J. Colorimetric Ethanol Indicator Based on Instantaneous, Localized Wetting of a Photonic Crystal. ACS Applied Materials & InterfacesACS Applied Materials & Interfaces. 2020;12 (1) :1924 - 1929. Publisher's Version
Phillips KR, Shirman T, Aizenberg M, England GT, Vogel N, Aizenberg J. Silica–titania hybrids for structurally robust inverse opals with controllable refractive index. Journal of Materials Chemistry C. 2020;8 (1) :109 - 116. Publisher's VersionAbstract
Templated from sacrificial colloidal assemblies, inverse opals are comprised of an interconnected periodic network of pores, forming a photonic crystal. They are used in a variety of applications, most of which, especially those in optics and photocatalysis, require a high degree of control over the long-range order, composition and refractive index. It has been shown that hybrid materials combining different components can yield materials with properties that are superior to the individual components. Here, we describe the assembly of hybrid titania/silica inverse opals using sol–gel chemistry, resulting in a mixed oxide with well-dispersed titanium and silicon. Titania has a high refractive index (2.4–2.9), but cracks typically form in the inverse opal structure; conversely, silica can produce highly ordered crack-free inverse opals, but it has a lower refractive index (∼1.4). By adjusting the ratio of titania and silica, the refractive index can be tailored while minimizing the crack density and maintaining structural order, allowing for control over the optical properties of this hybrid nanoporous material.
Korevaar PA, Kaplan CN, Grinthal A, Rust RM, Aizenberg J. Non-equilibrium signal integration in hydrogels. 2020;11 (1) :386. Publisher's VersionAbstract
Materials that perform complex chemical signal processing are ubiquitous in living systems. Their synthetic analogs would transform developments in biomedicine, catalysis, and many other areas. By drawing inspiration from biological signaling dynamics, we show how simple hydrogels have a previously untapped capacity for non-equilibrium chemical signal processing and integration. Using a common polyacrylic acid hydrogel, with divalent cations and acid as representative stimuli, we demonstrate the emergence of non-monotonic osmosis-driven spikes and waves of expansion/contraction, as well as traveling color waves. These distinct responses emerge from different combinations of rates and sequences of arriving stimuli. A non-equilibrium continuum theory we developed quantitatively captures the non-monotonic osmosis-driven deformation waves and determines the onset of their emergence in terms of the input parameters. These results suggest that simple hydrogels, already built into numerous systems, have a much larger sensing space than currently employed.
Magnabosco G, Papiano I, Aizenberg M, Aizenberg J, Falini G. Beyond biotemplating: multiscale porous inorganic materials with high catalytic efficiency. Chemical Communications. 2020;56 (23) :3389 - 3392. Publisher's VersionAbstract
Biotemplating makes it possible to prepare materials with complex structures by taking advantage of nature's ability to generate unique morphologies. In this work, we designed and produced a multi-scale porosity (MSP) scaffold starting from sea urchin spines by adding an additional nano-porosity to its native micro-porosity. The final replica shows porosity in both length scales and is an effective high-performing photocatalytic material.
Luneau M, Guan E, Chen W, Foucher AC, Marcella N, Shirman T, Verbart DMA, Aizenberg J, Aizenberg M, Stach EA, et al. Enhancing catalytic performance of dilute metal alloy nanomaterials. 2020;3 (1) :46. Publisher's VersionAbstract
Dilute alloys are promising materials for sustainable chemical production; however, their composition and structure affect their performance. Herein, a comprehensive study of the effects of pretreatment conditions on the materials properties of Pd0.04Au0.96 nanoparticles partially embedded in porous silica is related to the activity for catalytic hydrogenation of 1-hexyne to 1-hexene. A combination of in situ characterization and theoretical calculations provide evidence that changes in palladium surface content are induced by treatment in oxygen, hydrogen and carbon monoxide at various temperatures. In turn, there are changes in hydrogenation activity because surface palladium is necessary for H2 dissociation. These Pd0.04Au0.96 nanoparticles in the porous silica remain structurally intact under many cycles of activation and deactivation and are remarkably resistant to sintering, demonstrating that dilute alloy catalysts are highly dynamic systems that can be tuned and maintained in a active state.
2019
Luneau M, Shirman T, Filie A, Timoshenko J, Chen W, Trimpalis A, Flytzani-Stephanopoulos M, Kaxiras E, Frenkel AI, Aizenberg J, et al. Dilute Pd/Au Alloy Nanoparticles Embedded in Colloid-Templated Porous SiO2: Stable Au-Based Oxidation Catalysts. Chemistry of MaterialsChemistry of Materials. 2019;31 (15) :5759 - 5768. Publisher's Version
McCoy DE, McCoy VE, Mandsberg NK, Shneidman AV, Aizenberg J, Prum RO, Haig D. Structurally assisted super black in colourful peacock spiders. Proceedings of the Royal Society B: Biological SciencesProceedings of the Royal Society B: Biological Sciences. 2019;286 (1902) :20190589. Publisher's Version
Magnabosco G, Polishchuk I, Palomba F, Rampazzo E, Prodi L, Aizenberg J, Pokroy B, Falini G. Effect of Surface Chemistry on Incorporation of Nanoparticles within Calcite Single Crystals. Crystal Growth & DesignCrystal Growth & Design. 2019;19 (8) :4429 - 4435. Publisher's Version
Shahsafi A, Joe G, Brandt S, Shneidman AV, Stanisic N, Xiao Y, Wambold R, Yu Z, Salman J, Aizenberg J, et al. Wide-Angle Spectrally Selective Absorbers and Thermal Emitters Based on Inverse Opals. ACS PhotonicsACS Photonics. 2019;6 (11) :2607 - 2611. Publisher's Version

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