RESUMEN
Production of objects with varied mechanical properties is challenging for current manufacturing methods. Additive manufacturing could make these multimaterial objects possible, but methods able to achieve multimaterial control along all three axes of printing are limited. Here we report a multi-wavelength method of vat photopolymerization that provides chemoselective wavelength-control over material composition utilizing multimaterial actinic spatial control (MASC) during additive manufacturing. The multicomponent photoresins include acrylate- and epoxide-based monomers with corresponding radical and cationic initiators. Under long wavelength (visible) irradiation, preferential curing of acrylate components is observed. Under short wavelength (UV) irradiation, a combination of acrylate and epoxide components are incorporated. This enables production of multimaterial parts containing stiff epoxide networks contrasted against soft hydrogels and organogels. Variation in MASC formulation drastically changes the mechanical properties of printed samples. Samples printed using different MASC formulations have spatially-controlled chemical heterogeneity, mechanical anisotropy, and spatially-controlled swelling that facilitates 4D printing.
RESUMEN
An efficient method is presented for the synthesis of novel donor-acceptor silole chromophores through selective monohalogenation of 2,5-dimetallosiloles followed by Negishi alkyne cross-coupling reactions. The electronic properties and crystal packing of these new siloles can be controlled through judicious combinations of peripheral functional groups.
RESUMEN
[structure: see text]. We report the synthesis of 3,4,7,8,9,10,13,14-octadehydro[14]annulene (1) and detail a comparative aromaticity study with its benzannelated derivatives (e.g., 2 and 3).
RESUMEN
Enhanced global delocalization throughout the "stepped" π-electron systems of the [2.2]paracyclophane/dehydrobenzoannulene (PC/DBA) hybrids 1 and 2 is strongly suggested by a comparison of their electronic absorption spectra with those of model compounds with complete and interrupted classical aromatic delocalization. A distinct bathochromic shift (for 1) and greater absorption intensity at higher wavelengths (for 1 and 2) is observed versus the corresponding model hydrocarbons.