The emergence of 2D electrically conductive metal–organic frameworks (MOFs) has significantly expanded the scope of metal–organic framework applications from electrochemical energy storage to electronic devices. However, their potentials are not fully exploited due to limited accessibility to internal pores in stacked 2D structures. Herein we transform a 2D conjugated MOF into a 3D framework via postsynthetic pillar-ligand insertion. Cu-THQ was chosen due to its ability to adopt additional ligands at the axial positions at the copper nodes. Cu-THQ demonstrates that structural augmentation increases ion accessibility into internal pores, resulting in an increased gravimetric capacitance up to double that of the pristine counterpart. Beyond this, we believe that our findings can further be used to functionalize the existing 2D conductive MOFs to offer more opportunities in sensing, electronic, and energy-related applications by utilizing additional functions and increased accessibility from the pillars.

ABSTRACT:We have investigated the formation of high-strength, high-modulus fibers from four aliphatic polyketone resins. One resin was a perfectly alternating copolymer of ethylene and carbon monoxide, while the other three were terpolymers containing up to 6 mol % propylene. The mechanical properties were measured as a function of processing conditions, and the structures of the filaments were characterized using birefringence, WAXS, SAXS, SEM, and thermal analysis. Fibers formed from all resins develop very high molecular orientations and a microfibrillar structure. Fibers having room temperature tenacities as high as 10 gpd (ϳ1.1 GPa) were obtained. Tensile moduli reached values as high as 120 gpd (ϳ13 GPa). The melting point of the fibers was primarily dependent on the composition of the resin, while the maximum strength and modulus were largely determined by the maximum draw ratio achieved. The maximum draw ratio achieved in the present experiments was greater for the terpolymers than for the copolymer.

SynopsisA new process for making equal biaxially oriented films from liquid crystalline solutions of' poly(p-phenylene terephthalamide) (PPD-T) is described. The process involves extruding solutions of PPD-T/HzSO* through an annular die and over an oil-coated mandrel into a coagulation bath. The films were studied using wide angle X-ray diffraction (WAXS) and scanning electron microscopy (SEM). Tensile stress-strain properties were obtained on samples cut at various directions in the plane of the film. Biaxially oriented films which possess equal properties in the various directions in the plane of the film were produced. Moduli of 2.3 X lo9 Pa and tensile strengths of 9.6 X lo7Pa were obtained in the plane of the film. Films with unequal biaxial orientation were also produced. These tend to have higher modulus/tensile strength in the direction of major orientation, the machine direction (up to 8.3 X lo9 Pa/2.5 X 10s Pa), but become brittle in the transverse direction.

Electrically conductive metal−organic frameworks have emerged as an attractive class of materials for sensing and energy storage applications with unique electronic properties. However, the field lacks structural diversity often because of the limited choices for metal nodes. In this regard, the incorporation of iron species has been desirable due to its rich redox chemistry. Herein, we report an Fe-based twodimensional (2D) electrically conductive MOF with 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP), namely, Fe−HHTP, that shows redox features and mesoporosity. Fe− HHTP exhibits an electrical conductivity of 3.55 × 10 −5 S cm −1 despite a large interlayer spacing of ∼6.5 Å due to N,N-dimethylformamide (DMF) coordination on the Fe nodes. Spectroscopic results confirm that Fe−HHTP exhibits a mixed valency of Fe(II)/Fe(III) with Fe(II) being dominant. Fe−HHTP boasts exceptional capacitance and apparent redox activity compared to the previously reported analogues using the same ligand. We envision that Fe−HHTP can be an excellent candidate for applications in chemical sensing and energy storage where discrete redox features are essential.

Three polypropylene polymer samples possessing three different molecular weight distributions (MWD) ranging from narrow to broad, but having the same melt flow, were studied. The three resins were used to produce uniaxially oriented stretched tapes, which were evaluated for physical properties and morphological characteristics. In addition, five different drawing temperatures were used to investigate the effect of temperature on the physical properties and molecular morphology of the tape. As the MWD became broader, the tape modulus and tenacity increased slightly and the percent elongation and shrinkage decreased slightly. These effects were attributed to decreases in molecular mobility and increases in the number of tie molecules present in broad MWD resins. Morphological studies determined that the crystalline orientation was not affected by MWD. However, the amorphous orientation, at higher draw temperatures, demonstrated a small increase as the MWD became broader. MWD did not have a large effect on the percent crystallinity but the long period spacing (LPS) did exhibit a small decrease as the MWD broadened.