Exploiting the interplay of anisotropic diamagnetic susceptibility of liquid crystalline monomers and site selective photopolymerization enables the fabrication of 3D freeforms with highly refined microstructures. Utilizing chain transfer agents in the mesogenic inks presents a pathway for broadly tuning the mechanical properties of liquid crystalline polymers and their response to stimuli. In particular, the combination of 1,4-benzenedimethanethiol and tetrabromomethane is shown to enable voxelated blueprinting of molecular order, while allowing for a modulation of the crosslink density and the mechanical properties.
View Article and Find Full Text PDFThe effect of chain extender structure and composition on the thermomechanical properties of liquid crystal elastomers (LCE) synthesized using thiol-acrylate Michael addition is presented. The intrinsic molecular stiffness of the thiol chain extender and its relative molar ratio to acrylate-based host mesogens determine the magnitudes of the thermomechanical strains, temperatures at which they are realized and the mechanical work-content. A non-linear structure-property relationship emerges, wherein higher concentrations of flexible extenders first magnify the thermomechanical sensitivity, but a continued increase leads to weaker actuation.
View Article and Find Full Text PDFACS Appl Mater Interfaces
August 2019
The ability to pattern material response, voxel by voxel, to direct actuation and manipulation in macroscopic structures can enable devices that utilize ambient stimuli to produce functional responses at length scales ranging from the micro- to the macroscopic. Fabricating liquid crystalline polymers (LCPs), where the molecular director is indexably defined in three-dimensional (3D) freeforms, can be a key enabler. Here, the combination of anisotropic magnetic susceptibility of the liquid crystalline monomers in a reorientable magnetic field and spatially selective photopolymerization using a digital micromirror device to independently define molecular orientation in light and/or heat-responsive multimaterial elements, which are additively incorporated into 3D freeforms, is exploited.
View Article and Find Full Text PDFThe most common clinical syndromes presenting with paragangliomas and/or pheochromocytomas as their endocrine components are multiple endocrine neoplasia type 2, neurofibromatosis, Von Hippel-Lindau syndrome, Carney-Stratakis syndrome, Carney triad, and the recently described hereditary paraganglioma syndrome. Only Carney triad is known to also present with adrenocortical adenomas, currently representing the only described syndrome in which all 3 of the aforementioned tumors are found together. In most cases, prototypical lesions of the triad such as gastrointestinal stromal tumor and pulmonary chondromas are also seen.
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