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Two types of additive manufacturing (AM) techniques, fused filament fabrication (FFF) and selective laser sintering (SLS), were employed to fabricate specimens from three widely used AM polymers: polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and polyamide (PA): the first two using FFF and PA using SLS. The single‐edge notch bending (SENB) test was employed to measure the mode‐I fracture toughnesses of bulk and AM specimens in three directions relative to the printing direction. Unlike their bulk counterparts, AM polymers exhibited anisotropic fracture toughness. The degree of anisotropy in FFF‐PLA was much larger than FFF‐ABS and SLS‐PA. The smallest fracture toughness value for each AM polymer was achieved along the transverse printing direction. Different AM techniques affect fracture toughness differently. For instance, FFF is shown to increase PLA's plastic deformation, while SLS reduces PA's ductility. The decrease in fracture toughness is consistently observed when transitioning from bulk polymers to AM ones, reaching as much as 75%. This study provides insights into the fracture toughness of AM parts made via popular plastics, which are crucial for designing structural parts using FFF and SLS processes. Highlights: Additively manufactured polymers always exhibit some anisotropic fracture toughnessDifferent additive manufacturing techniques affect the fracture toughness differentlyFused filament fabrication increases polylactic acid's plastic deformationBut selective laser sintering reduces polyamide's ductility [ABSTRACT FROM AUTHOR]

Nanofibers based on phenanthroimidazole derivatives PCC, PDC, and PSC were fabricated by organogelation processes, and their fluorescence sensory properties towards acid were investigated. It was found that the emission of PCC in the nanofiber-based film could be quenched significantly upon exposure to gaseous TFA due to the formation of protonated PCC, in which ICT (intramolecular charge transfer) would occur. On the other hand, TFA vapor led to the emitting colors of PDC and PSC in the nanofiber-based films to turn to yellow and green from sky blue and blue, respectively. Additionally, we found that the decay times of PCC were 0.1 s and 1.9 s in probing the saturated vapor of TFA in nanofiber-based film and in spin-coated film, respectively. The results suggested that the high surface-to-volume ratio and large interspace in the nanofiber-based networks favored the enhanced adsorption, accumulation, and diffusion of gaseous molecules, resulting in such a high performance. [ABSTRACT FROM AUTHOR]