In this paper we describe methods for manipulating the morphology of side-chain liquid crystalline block copolymers through variations in the liquid crystalline content. By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer (BCP) backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase segregated BCP microstructures can be precisely manipulated. Increases in LC functionalization lead to stronger preferences for the anchoring of the LC mesophase relative to the substrate and the inter-material dividing surface (IMDS). By manipulating the strength of these interactions the arrangement and ordering of the ultrathin film block copolymer nanostructures can be controlled, yielding a range of morphologies that includes perpendicular and parallel cylinders, as well as both perpendicular and parallel lamellae. Additionally, we demonstrate the utilization of selective etching to create a nanoporous liquid crystalline polymer thin film. The unique control over the orientation and order of the self-assembled morphologies with respect to the substrate will allow for the custom design of thin films for specific nano-patterning applications without manipulation of the surface chemistry or the application of external fields. Keywords liquid crystal; block copolymer; thin films; selective etchingRecently there has been a great deal of research directed at controlling the self-assembly of block copolymer thin films, with specific interest in obtaining the desired orientation of nanoscale features relative to the substrate, such as perpendicular or parallel cylinders 1, 2 . Progress has been made in controlling the morphologies of block copolymer thin films through techniques such as solvent annealing 3, 4 , zone casting 5 , electric field alignment 6 , optical alignment 7 , topographical patterning 8, 9 , and chemical substrate patterning 10-12 . Due to the large interfacial area of thin films, the orientation of the domains depends greatly upon the relative surface energies of the blocks 13-16 . We will show that the incorporation of a liquid crystalline (LC) component into such systems offers a powerful tool for manipulating the Hammond@mit.edu. orientation of the self-assembled structures. When an LC component is introduced, several factors such as conformational asymmetry, structural asymmetry, and the anchoring of the LC mesophase to the inter-material dividing surface (IMDS) can alter the self-assembly behavior 17-24 . The two possible scenarios for smectic LC anchoring relative to an interface -such as a substrate or the IMDS -are homeotropic or homogeneous, where the smectic layer normal is perpendicular or parallel to the interface, respectively. It has been shown that the LC mesophase will preferentially orient with respect to the IMDS due to surface stabilization effects 25-27 . In this way a well oriented block copolymer mesophase can be used to template order in the LC mesophase. Additionally, liquid crystalline polymers (LCP) are ...

Manipulation makes light work: The morphology and rheological properties of a liquid‐crystalline system can be dynamically manipulated with UV light by attaching photoresponsive liquid‐crystalline moieties to a siloxane‐based polymer. Stimulation with UV light induces a conformational change in the molecule, which disrupts the liquid‐crystalline mesophase (see picture), and results in a dramatic change in its rheological properties.magnified image

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Extensive characterisations of the zebrafish genome and proteome have established a foundation for the use of the zebrafish as a model organism; however, characterisation of the zebrafish lipidome has not been as comprehensive. In an effort to expand current knowledge of the zebrafish sphingolipidome, a Parallel Reaction Monitoring (PRM)-based liquid chromatography-mass spectrometry (LC-MS) method was developed to comprehensively quantify zebrafish ceramides. Comparison between zebrafish and a human cell line demonstrated remarkable overlap in ceramide composition, but also revealed a surprising lack of most sphingadiene-containing ceramides in the zebrafish. PRM analysis of zebrafish embryogenesis identified developmental stage-specific ceramide changes based on long chain base (LCB) length. A CRISPR-Cas9-generated zebrafish model of Farber disease exhibited reduced size, early mortality, and severe ceramide accumulation where the amplitude of ceramide change depended on both acyl chain and LCB lengths. Our method adds an additional level of detail to current understanding of the zebrafish lipidome, and could aid in the elucidation of structure-function associations in the context of lipid-related diseases.

Human infants exhibit innate social behaviors at birth, yet little is understood about the embryonic development of sociality. We screened 1120 known drugs and found that embryonic inhibition of topoisomerase IIα (Top2a) resulted in lasting social deficits in zebrafish. In mice, prenatal Top2 inhibition caused behavioral defects related to core symptoms of autism, including impairments in social interaction and communication. Mutation of Top2a in zebrafish caused downregulation of a set of genes highly enriched for genes associated with autism in humans. Both the Top2a-regulated and autism-associated gene sets possess binding sites for polycomb repressive complex 2 (PRC2), a regulatory complex responsible for H3K27 trimethylation. Moreover, both gene sets are highly enriched for H3K27me3. Inhibition of PRC2 component Ezh2 rescued social deficits caused by Top2 inhibition. Therefore, Top2a is a key component of an evolutionarily conserved pathway that promotes the development of social behavior through PRC2 and H3K27me3.