MRSEC Program Overview

Welcome to the internet hub of the Materials Research Science and Engineering Centers (MRSEC). This website provides organized information and resources at the various MRSECs for the international scientific, industrial, and educational materials research and development communities.

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Program Highlights

May 22, 2015

Surface Alignment and Handedness of Chromonic Liquid Crystals

Fig. 2.  (left) A twisted escaped-radial (TER) director configuration; in the perspective view, yellow rods represent LC directors which escape to the left (West).  (right) Schematic diagram of a radial defect between two chiral TER domains, and (top-right) polarization microscopy image of the corresponding defect. 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].

Collings, Lubensky & Yodh applied the scheme to become the first to realize homeotropic surface alignment of CLCs in geometries with curvature. In cylinders, the interplay between anisotropic elasticity, surface anchoring, and confinement geometry caused the CLCs to adopt chiral structures even though they are achiral materials [2]. Experiments in cylinders discovered a new LC structure, the twisted escaped-radial configuration, and new classes of topological defects that arise because twist-handedness and escape-direction can be different (Fig. 2). The work teaches about the origins of chirality or “handedness,” and it suggests a novel mechanism for how nature can be exploited to create right- and left-handed functional structures.

[1] J. Jeong et al. (Langmuir, 2014).
[2] J. Jeong et al., (under review 2015).

May 19, 2015

Multifunctional Fiber Probes Provide New Tools for Integrating the Brain and Spinal Cord

MIT MRSEC researchers have developed flexible, multifunctional implantable probes that make it possible to simultaneously stimulate and record single cell neural activity, with the option of delivering therapeutic agents through the probe.