2017

Shirman E, Shirman T, Shneidman AV, Grinthal A, Phillips KR, Whelan H, Bulger E, Abramovitch M, Patil J, Nevarez R, et al. Modular Design of Advanced Catalytic Materials Using Hybrid Organic–Inorganic Raspberry Particles. Adv. Func. Mater. [Internet]. 2017 :1704559. Publisher's VersionAbstract

Catalysis is one of the most sophisticated areas of materials research that encompasses a diverse set of materials and phenomena occurring on multiple length and time scales. Designing catalysts that can be broadly applied toward global energy and environmental challenges requires the development of universal frameworks for complex catalytic systems through rational and independent (or quasi-independent) optimization of multiple structural and compositional features. Toward addressing this goal, a modular platform is presented in which sacrificial organic colloids bearing catalytic nanoparticles on their surfaces self-assemble with matrix precursors, simultaneously structuring the resulting porous networks and fine-tuning the locations of catalyst particles. This strategy allows combinatorial variations of the material building blocks and their organization, in turn providing numerous degrees of freedom for optimizing the material’s functional properties, from the nanoscale to the macroscale. The platform enables systematic studies and rational design of efficient and robust systems for a wide range of catalytic and photocatalytic reactions, as well as their integration into industrial and other real-life environments.

Aizenberg M, Okeyoshi K, Aizenberg J. Inverting the Swelling Trends in Modular Self-Oscillating Gels Crosslinked by Redox-Active Metal Bipyridine Complexes. Adv. Func. Mater. [Internet]. 2017 :1704205. Publisher's VersionAbstract

The developing field of active, stimuli-responsive materials is in need for new dynamic architectures that may offer unprecedented chemomechanical switching mechanisms. Toward this goal, syntheses of polymerizable bipyridine ligands, bis(4-vinylbenzyl)[2,2′-bipyridine]-4,4′-dicarboxylate and N4,N4′-bis(4-vinylphenyl)-2,2′-bipyridine-4,4′-dicarboxamide, and a number of redox-active Ruthenium(II) and Iron(II) complexes with them are reported. Detailed characterizations by NMR, Fourier transform infrared spectroscopy, high-resolution mass-spectrometry, X-ray, and cyclic voltammetry show that the topology of these molecules allows them to serve as both comonomers and crosslinkers in polymerization reactions. Electronic properties of the ligands are tunable by choosing carboxylate- or carboxamido-linkages between the core and the vinylaryl moieties, leading to a library of Ru and Fe complexes with the M(III)/M(II) standard redox potentials suitable for catalyzing self-oscillating Belousov–Zhabotinskii (BZ) reaction. New poly(N-isopropylacrylamide)-based redox-responsive functional gels containing hydrophilic comonomers, which have been prepared using representative Ru bpy complexes as both a crosslinker and redox-active catalyst, exhibit a unique feature: their swelling/contraction mode switches its dependence on the oxidation state of the Ru center, upon changing the ratio of comonomers in the hybrid gel network. The BZ self-oscillations of such crosslinked hydrogels have been observed and quantified for both supported film and free-standing gel samples, demonstrating their potential as chemomechanically active modules for new functional materials.

2017 MRS Medal

October 24, 2017
The MRS Medal recognizes a specific outstanding recent discovery or advancement, which is expected to have a major impact on the progress of a materials-related field.  Joanna Aizenberg has been awarded a Medal “for developing new synthesis routes inspired by biological principles for the fabrication of advanced complex multifunctional materials and devices.”

Havinga Medal

October 24, 2017
The Havinga Foundation of the Leiden Institute of Chemistry of Leiden University, The Netherlands, has awarded Joanna Aizenberg the Havinga Medal. The Medal is awarded to a distinguished chemical scientist who is a leader in groundbreaking fundamental and applied molecular research. You can read about the Havinga Medal at http://www.... Read more about Havinga Medal
Kumar K, Liu J, Christianson C, Ali M, Tolley MT, Aizenberg J, Ingber DE, Weaver JC, Bertoldi K. A Biologically Inspired, Functionally Graded End Effector for Soft Robotics Applications. Soft Robotics [Internet]. 2017;4 (4) :317-323. Publisher's VersionAbstract

Soft robotic actuators offer many advantages over their rigid counterparts, but they often are unable to apply highly localized point loads. In contrast, many invertebrates have not only evolved extremely strong ‘‘hybrid appendages’’ that are composed of rigid ends that can grasp, puncture, and anchor into solid substrates, but they also are compliant and resilient, owing to the functionally graded architecture that integrates rigid termini with their flexible and highly extensible soft musculatures. Inspired by the design principles of these natural hybrid appendages, we demonstrate a synthetic hybrid end effector for soft-bodied robots that exhibits excellent piercing abilities. Through the incorporation of functionally graded interfaces, this design strategy minimizes stress concentrations at the junctions adjoining the fully rigid and soft components and optimizes the bending stiffness to effectively penetrate objects without interfacial failure under shear and compressive loading re- gimes. In this composite architecture, the radially aligned tooth-like elements apply balanced loads to maximize puncturing ability, resulting in the coordinated fracture of an object of interest.

Shirman T, Lattimer J, Luneau M, Shirman E, Reece C, Aizenberg M, Madix RJ, Aizenberg J, Friend CM. New Architectures for Designed Catalysts: Selective Oxidation using AgAu Nanoparticles on Colloid-Templated Silica. Chem. Eur. J. [Internet]. 2018;24 :1833 –1837 . Publisher's VersionAbstract

A highly modular synthesis of designed catalysts with controlled bimetallic nanoparticle size and composition and a well-defined structural hierarchy is demonstrated. Exemplary catalysts—bimetallic dilute Ag-in-Au nanoparticles partially embedded in a porous SiO2 matrix (SiO2–AgxAuy)— were synthesized by the decoration of polymeric colloids with the bimetallic nanoparticles followed by assembly into a colloidal crystal backfilled with the matrix precursor and subsequent removal of the polymeric template. This work reports that these new catalyst architectures are significantly better than nanoporous dilute AgAu alloy catalysts (nanoporous Ag3Au97) while retaining a clear predictive relationship between their surface reactivity with that of single-crystal Au surfaces. This paves the way for broadening the range of new catalyst architectures required for translating the designed principles developed under controlled conditions to designed catalysts under operating conditions for highly selective coupling of alcohols to form esters. Excellent catalytic performance of the porous SiO2–AgxAuy structure for selective oxidation of both methanol and ethanol to produce esters with high conversion efficiency, selectivity, and stability was demonstrated, illustrating the ability to translate design principles developed for support-free materials to the colloid-templated structures. The synthetic methodology reported is customizable for the design of a wide range of robust catalytic systems inspired by design principles derived from model studies. Fine control over the composition, morphology, size, distribution, and availability of the supported nanoparticles was demonstrated.

Amini S, Kolle S, Petrone L, Ahanotu O, Sunny S, Sutanto CN, Hoon S, Cohen L, Weaver JC, Aizenberg J, et al. Preventing mussel adhesion using lubricant-infused materials. Science [Internet]. 2017;357 (6352) :668-673. Publisher's VersionAbstract

Mussels are opportunistic macrofouling organisms that can attach to most immersed solid surfaces, leading to serious economic and ecological consequences for the maritime and aquaculture industries. We demonstrate that lubricant-infused coatings exhibit very low preferential mussel attachment and ultralow adhesive strengths under both controlled laboratory conditions and in marine field studies. Detailed investigations across multiple length scales—from the molecular-scale characterization of deposited adhesive proteins to nanoscale contact mechanics to macroscale live observations—suggest that lubricant infusion considerably reduces fouling by deceiving the mechanosensing ability of mussels, deterring secretion of adhesive threads, and decreasing the molecular work of adhesion. Our study demonstrates that lubricant infusion represents an effective strategy to mitigate marine biofouling and provides insights into the physical mechanisms underlying adhesion prevention.

Daniel D, Timonen JVI, Li R, Velling SJ, Aizenberg J. Oleoplaning droplets on lubricated surfaces. Nat. Phys. [Internet]. 2017;13 (10) :1020-1025. Full TextAbstract

Recently, there has been much interest in using lubricated surfaces to achieve extreme liquid repellency: a foreign droplet immiscible with the underlying lubricant layer was shown to slide o at a small tilt angle <5◦ . This behaviour was hypothesized to arise from a thin lubricant overlayer film sandwiched between the droplet and solid substrate, but this has not been observed experimentally. Here, using thin-film interference, we are able to visualize the intercalated film under both static and dynamic conditions. We further demonstrate that for a moving droplet, the film thickness follows the Landau–Levich–Derjaguin law. The droplet is therefore oleoplaning—akin to tyres hydroplaning on a wet road—with minimal dissipative force and no contact line pinning. The techniques and insights presented in this study will inform future work on the fundamentals of wetting for lubricated surfaces and enable their rational design.

England GT, Russell C, Shirman E, Kay T, Vogel N, Aizenberg J. The Optical Janus Effect: Asymmetric Structural Color Reflection Materials. Adv. Mater. [Internet]. 2017;29 (29) :1606876. Publisher's VersionAbstract
Structurally colored materials are often used for their resistance to photobleaching and their complex viewing-direction-dependent optical properties. Frequently, absorption has been added to these types of materials in order to improve the color saturation by mitigating the effects of nonspecific scattering that is present in most samples due to imperfect manufacturing procedures. The combination of absorbing elements and structural coloration often yields emergent optical properties. Here, a new hybrid architecture is introduced that leads to an interesting, highly directional optical effect. By localizing absorption in a thin layer within a transparent, structurally colored multilayer material, an optical Janus effect is created, wherein the observed reflected color is different on one side of the sample than on the other. A systematic characterization of the optical properties of these structures as a function of their geometry and composition is performed. The experimental studies are coupled with a theoretical analysis that enables a precise, rational design of various optical Janus structures with highly controlled color, pattern, and fabrication approaches. These asymmetrically colored materials will open applications in art, architecture, semitransparent solar cells, and security features in anticounterfeiting materials.

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