4 research outputs found
Hydrophobicity and dielectric properties across an isostructural family of MOFs: a duet or a duel?
An isoreticular family of metal-organic frameworks is post-synthetically subjected to polymer grafting. Surface hydrophobicity analysis, adsorption experiments, and impedance spectroscopy characterise the water molecules adsorbed, both on the surface and in the pores, while resolving how molecular mobility is impacted
Spanish Poplar Biomass as a Precursor for Nanocellulose Extraction
The effect of acidic hydrolysis duration on nanocellulose size, morphology, and proper ties
was investigated, which opens up a whole new horizon of versatility in poplar applications. This
study aimed to examine Spanish poplar wastes as raw material to extract crystalline nanocellulose
(CNC), which substantiates the importance of poplar wastes. Wastes were pulped using 1 L of
10% NaOH (wt./wt.) solution, and bleached several times by NaClO2
; afterwards, white wastes
were subjected to acidic hydrolysis by 60% H2SO4
for either 5, 10, or 15 min. Microcrystalline
cellulose (MCC) underwent a similar hydrolysis protocol as poplar as control. TEM, IR, and XRD
characterization techniques were performed. Poplar based nanocellulose sized 219 nm length and
69 nm width after 15 min acidic hydrolysis. MCC yielded 122 nm length and 12 nm width crystals
after 10 min acidic hydrolysis. Hydrolysis resulted in a drastic change and intense peaks at 3500 and
2900 cm−1
for nanocellulose. Although pre-hydrolysis fiber treatment was not influencial on the
crystallinity of poplar, acidic hydrolysis remarkably raised the crystallinity index (CI) by 7–8%. The
more hydrolysis duration was prolonged, the size of the resulting crystal (whisker) decreased, and
the aspect ratio increased. Hydrolysis was more impactful on MCC than poplar. However, for future
work, it seems that longer duration of pulping and bleaching could have significantly removed
unwanted components (hemicellulose and lignin), showcased in IR and XRD, and hence smoothened
the following hydrolysis.European Union under umbrella of Erasmus+ KA107 PhD
Mobility schem
The Dielectric Behavior of Protected HKUST-1
We investigated the adsorption properties and the dielectric behavior of a very well-known metal-organic framework (MOF), namely Cu3(BTC)2 (known as HKUST-1; BTC = 1,3,5-benzenetricarboxylate), before and after protection with some amines. This treatment has the purpose of reducing the inherent hygroscopic nature of HKUST-1, which is a serious drawback in its application of as low-dielectric-constant (low-κ) material. Moreover, we investigated the structure of HKUST-1 under a strong electric field, confirming the robustness of the framework. Even under dielectric perturbation, the water molecules adsorbed by the MOF remained almost invisible to X-ray diffraction, apart from those directly bound to the metal ions. However, the replacement of H2O with a more visible guest molecule such as CH2Br2 made the cavity that traps the guest more visible. Finally, in this work we demonstrate that impedance spectroscopy is a valuable tool for identifying water sorption in porous materials, providing information that is complementary to that of adsorption isotherms
Poly[(μ4-phenylphosphonato)zinc(II)]
The title two-dimensional coordination polymer, [Zn(C6H5PO3)]n, was
synthesized serendipitously by reacting a tetraphosphonate cavitand
Tiiii[C3H7, CH3, C6H5] and Zn(CH3COO)22H2O in a DMF/H2O mixture. The
basic conditions of the reaction cleaved the phosphonate bridges at the upper
rim of the cavitand, making them available for reaction with the zinc ions. The
coordination polymer can be described as an inorganic layer in which zinc
coordinates the oxygen atoms of the phosphonate groups in a distorted
tetrahedral environment, while the phenyl groups, which are statistically
disordered over two orientations, point up and down with respect to the layer.
The layers interact through van der Waals interactions. The crystal studied was
refined as a two-component twin