Highlights

Molecules with switchable magnetic moment could become of considerable importance for the emerging field of organic spintronics, where the control of spin degrees of freedom may be performed electrically on the molecular scale.  Spin crossover complexes based on magnetic iron (Fe) ions are interesting in this regard because they exhibit a reversible transition between a high-spin and low-spin magnetic state, which can be induced by external stimuli such as temperature, pressure, electric field, and by light.

Nature has evolved numerous mechanisms for the self-healing of damaged tissues and structures.  MIT MRSEC researchers have shown first successes in establishing a new class of smart polymer materials with controllable network junctions by combining Diels-Alder reactions with bio-inspired metal coordinate crosslinking to generate multi-functional polymers capable of

Crystalline silicon is a critically important electronic material in all consumer electronic products.   The ability to create fibers from this material would open up exciting vistas for a new generation of fiber-based electronic and optical devices.  Traditional fiber-optic drawing involves a thermally mediated geometric scaling where both the fiber materials and their relative positions are identical to those found in the fiber preform. To date, all thermally drawn fibers are limited to the preform composition and geometry.

Monolayer molybdenum disulfide (MoS2) is a 3-atom thick material with a direct band gap, making it of interest for fundamental science as well as applications in optoelectronics and chemical sensing. Our innovation is a scalable method for “seeded growth” of high quality monolayer MoS2 at controlled locations, which is an important advance towards useful applications of the material.

How can we wrap a 3d object with a sheet of paper without folds? Wrapping implies the ability to stretch as much as bend.  Using concepts from fractal geometry, we have designed and realized a new class of materials with unprecedented control of stretchability and bendability to conformally wrap any shape or expand to nearly any predetermined shapes.   Fractal cut sheets for controlled expansion

In 2015 we will celebrate the arrival of our 600th REU student in our NSF-supported REU program. This program started in 1989 with a small grant that supported 5 minority students. Over the following 26 years, we have averaged 23 students/yr by supplementing our MRSEC–supported students with an additional DMR REU Site grant that supported 10 students per year and some individual faculty contributions. Overall, 61% of our students were from under-represented groups (39% minority and 43% women) in STEM departments.

A central goal of IRG-4 is to use collective interactions between dissimilar nanocrystals to enhance the performance of their assemblies. Here we demonstrate plasmonic enhancement of optical upconversion luminescence within nanorod-nanophosphor heterodimers (Fig 1a-c). Using experiment and theory we are able to develop design rules for optimizing heterodimer geometry. The templated assembly process (Fig 1d-e) can be used for many other nanocrystal building blocks and for larger assemblies.

In crystalline materials, topologial defects such as dislocations mark flow defects, or “soft spots,” corresponding to local regions that are likely to rearrange due to thermal fluctuations or an applied load.  In disordered packings, it is extremely difficult to identify the corresponding soft spots. We previously discovered that sound waves are strongly scattered by flow defects, enabling us to identify soft spots acoustically.

Dendrimers are branched molecules of precise chemistry, and Janus-dendrimers are dendrimers that have two distinct faces, with unique chemistry corresponding to each face. Here, we made a library of carbohydrate containing glycodendrimers (GD) that self assemble into vesicles – a structure that mimics biological materials such as viruses. We show the vesicles have the ability to agglutinate lectin proteins at vesicle walls, owing to the chemistry and concentration of the carbohydrate.  Synthesis of these materials is the first step in the assembly of a synthetic virus.

Chromonic liquid crystals (CLCs) are different from typical LCs used in displays, in part because they “live” in water and thus hold untapped potential for coupling LC phenomenology with biological media. Furthermore, CLCs twist very easily compared to bend and splay deformation, and the consequences of this giant elastic anisotropy are not well understood. Recently, Collings, Lubensky, Yodh & Johnson developed a new alignment layer for CLCs based on parylene (Fig. 1); it enabled homeotropic surface anchoring (i.e., perpendicular anchoring) [1].