Exploiting Partial Solubility in Partially Fluorinated Thermoplastic Blends to Improve Adhesion during Fused Deposition Modeling.

This work studies the effect of interlayer adhesion on mechanical performance of fluorinated thermoplastics produced by fused deposition modeling (FDM). Here, we study the anisotropic mechanical response of 3D-printed binary blends of poly (vinylidene fluoride) (PVDF) and poly (methyl methacrylate) (PMMA) with the isotropic mechanical response of these blends fabricated via injection molding. Various PVDF/PMMA filament compositions were produced by twin-screw extrusion and, subsequently, injection-molded or 3D printed into dog-bone shapes. Specimen mechanical and thermal properties were evaluated by mode I tensile testing and differential scanning calorimetry, respectively. Results show that higher PMMA concentration not only improved the tensile strength and decreased ductility but reduced PVDF crystallization. As expected, injection-molded samples revealed better mechanical properties compared to 3D printed specimens. Interestingly, 3D printed blends with lower PMMA content demonstrated better diffusion (adhesion) across interfaces than those with a higher amount of PMMA. The present study provides new findings that may be used to tune mechanical response in 3D printed fluorinated thermoplastics, particularly for energy applications.

Halogen Bonding in Dithiane/Iodofluorobenzene Mixtures: A New Class of Hydrophobic Deep Eutectic Solvents.

While research into deep eutectic solvents (DESs) has expanded over the previous two decades, the focus has remained on the utilization of hydrogen bond donors in these systems. Additionally, the majority of the known DESs rely on at least one ionic component. Through the combination of 1,3-dithiane and 1,2-diiodo-3,4,5,6-tetrafluorobenzene (1,2-F4 DIB), we report the first known DES based on halogen bonding. This mixture remains a liquid, with a eutectic melting temperature of 13.7 °C over a range of 1,3-dithiane mole fraction (0.35 to 0.75). Additionally, cocrystals of 1,3- and 1,4-dithiane with 1,2-, 1,3-, and 1,4-F4 DIB, as well as 1,3,5-trifluoro-2,4,6-triiodobenzene were studied via single-crystal X-ray diffraction. These data reveal a wide range of halogen bonding strengths (0.85