X-ray and FTIR \u3bc-CTs for morphological and chemical characterization of eco-sustainable insulating foams

Here it is reported a multidisciplinary approach based on tomography and infrared techniques applied to the characterization of tannin porous rigid foams, potentially usable as new insulating materials in green building technology. With conventional x-ray tomography it was possible to preliminary evaluate the homogeneity of the samples at low resolution, while then, thanks to the synchrotron source, it was possible to obtain more detailed information at a micro-scale level. At the same time chemical characterization was done through Fourier Transform infrared (FTIR) imaging. Conventionally, FTIR imaging is limited to a planar projection, not considering the 3D structure of the material. To avoid this limitation, a FTIR 3D-tomography setup was built and the foams characterized by a chemical point of view. The idea is to directly correlate these data with the 3D-structural information obtained with the x-ray computed tomography exploiting the synchrotron radiation as source, allowing a complete characterization of the material morphology and chemistry at the microscale

Understanding the Polymerization of Polyfurfuryl Alcohol: Ring Opening and Diels-Alder Reactions

Polyfurfuryl alcohol (PFA) is one of the most intriguing polymers because, despite its easy polymerization in acid environment, its molecular structure is definitely not obvious. Many studies have been performed in recent decades, and every time, surprising aspects came out. With the present study, we aim to take advantage of all of the findings of previous investigations and exploit them for the interpretation of the completely cured PFA spectra registered with three of the most powerful techniques for the characterization of solid, insoluble polymers: Solid-State 13C-NMR, Attenuated Total Reflectance (ATR), Fourier Transform Infrared (FTIR) spectroscopy, and UV-resonant Raman spectroscopy at different excitation wavelengths, using both an UV laser source and UV synchrotron radiation. In addition, the foreseen structures were modeled and the corresponding 13C-NMR and FTIR spectra were simulated with first-principles and semi-empiric methods to evaluate their matching with experimental ones. Thanks to this multi-technique approach, based on complementary analytical tools and computational support, it was possible to conclude that, in addition to the major linear unconjugated polymerization, the PFA structure consists of Diels-Alder rearrangements occurring after the opening of some furanic units, while the terminal moieties of the chain involves \u3b3-lactone arrangements. The occurrence of head-head methylene ether bridges and free hydroxyl groups (from unreacted furfuryl alcohol, FA, or terminal chains) could be excluded, while the conjugated systems could be considered rather limited

Synthesis and Characterization of High-Performing Sulfur-Free Tannin Foams

Tannin foams are green lightweight materials that have attracted industrial interest for the manufacturing of sandwich panels for insulation purposes. However, the dimensions of the cells and the presence of sulfur in the formulation developed until now have discouraged their upscaling. In this work, we present the synthesis and the characterization of the more promising small cell and sulfur-free materials. It was observed that, with respect to standard ones, foams catalyzed with nitric acid present similar physical properties and more phenolic character, which favors the absorption of ionic pollutants. Conversely, the foams blown with aliphatic solvents and surfactants present smaller pores, and higher mechanical and insulating properties, without a\ufb00ecting the chemical properties or the heating value. The combined foam produced with nitric acid as a catalyst and petroleum ether as a blowing agent result in sulfur-free and small cell material with overall improved features. These foams have been produced at 30 7 30 7 3 cm3, with high homogeneity and, to date, they represent the most suitable formulation for industrial upscaling

Turning biomass into functional composite materials: rice husk for fully renewable immobilized biocatalysts

Rice husk is an underexploited, low density and highly robust composite material, massively available from rice processing. Here we report two new procedures for the formulation of immobilized lipases applicable in fats and oils transformations. The enzymes were covalently anchored on aldehyde groups introduced on rice husk by laccase-catalysed oxidation of the cellulose component. The method avoids the use of toxic glutaraldehyde while allows for the application and recycling of the biocatalysts in aqueous media. The second method used a fluidized bed granulator for the coating of the particles of rice husk (200\u2013400 m) in the presence of water-soluble binders. The formulations are mechanically stable and suitable for applications in different hydrophobic media. Both methods allow for the recovery and reuse of the rice husk at the end of the life cycle of the biocatalysts

Interaction of chlorogenic acids and quinides from coffee with human serum albumin

Chlorogenic acids and their derivatives are abundant in coffee and their composition changes between coffee species. Human serum albumin (HSA) interacts with this family of compounds with high affinity. We have studied by fluorescence spectroscopy the specific binding of HSA with eight compounds that belong to the coffee polyphenols family, four acids (caffeic acid, ferulic acid, 5-O-caffeoyl quinic acid, and 3,4-dimethoxycinnamic acid) and four lactones (3,4-O-dicaffeoyl-1,5-c-quinide, 3-O-[3,4- (dimethoxy)cinnamoyl]-1,5-c-quinide, 3,4-O-bis[3,4-(dimethoxy)cinnamoyl]-1,5-c-quinide, and 1,3, 4-O-tris[3,4-(dimethoxy)cinnamoyl]-1,5-c-quinide), finding dissociation constants of the albumin\u2013chlorogenic acids and albumin\u2013quinides complexes in the micromolar range, between 2 and 30 lM. Such values are comparable with those of the most powerful binders of albumin, and more favourable than the values obtained for the majority of drugs. Interestingly in the case of 3,4-O-dicaffeoyl-1,5-c-quinide, we have observed the entrance of two ligand molecules in the same binding site, leading up to a first dissociation constant even in the hundred nanomolar range, which is to our knowledge the highest affinity ever observed for HSA and its ligands. The displacement of warfarin, a reference drug binding to HSA, by the quinide has also been demonstrated

Controlling Metal Halide Perovskite Crystal Growth via Microcontact Printed Hydrophobic‐Hydrophilic Templates

AbstractHerein, a simple, low‐cost, solution‐processed, and parallel fabrication method to form metal halide perovskite (MHP) poly and single‐crystalline films confined in ordered micrometer‐sized domains is reported. A cross‐linked polydimethylsiloxane (PDMS) stamp featuring 25 µm side squares is used to pattern their substrates. The substrate is microcontact printed on the PDMS inked with self‐assembled monolayers (SAMs) of alkanethiol to form a molecular template, resulting in hydrophilic (gold) and hydrophobic (alkanethiol) domains. The subsequent deposition of lead bromide (PbBr2) and methylammonium bromide (MABr) precursor solutions on the pre‐patterned substrate resulted in poly and single‐crystalline films of methylammonium lead bromide (MAPbBr3) confined to the hydrophilic domains. Two deposition methods: drop‐casting and two‐step spin‐coating are systematically investigated to find well confined and large‐sized single‐crystal MAPbBr3. Casting proves to be more effective than two‐step spin‐coating to achieve better confinement of MAPbBr3. The patterning process is monitored in dependence of the a) deposition methods used to b) precisely control the MAPbBr3 crystal growth in a pre‐defined site which leads to c) grow poly and single‐crystals in a periodic arrangement. Their nondestructive and less energy processable fabrication method will have its own contribution in transferring patterns to desired substrates that enables them to fabricate different types of MHP optoelectronic devices and integrated electronic systems with more complex architectures

Study of the Spatio-Chemical Heterogeneity of Tannin-Furanic Foams: From 1D FTIR Spectroscopy to 3D FTIR Micro-Computed Tomography

Tannin-furanic rigid foams are bio-based copolymers of tannin plant extract and furfuryl alcohol, promising candidates to replace synthetic insulation foams, as for example polyurethanes and phenolics, in eco-sustainable buildings thanks to their functional properties, such as lightness of the material and fire resistance. Despite their relevance as environmental-friendly alternatives to petroleum derivatives, many aspects of the polymerization chemistry still remain unclear. One of the open issues is on the spatial heterogeneity of the foam, i.e., whether the foam constituents prevalently polymerize in spatially segregated blocks or distribute almost homogenously in the foam volume. To address this matter, here we propose a multiscale FTIR study encompassing 1D FTIR spectroscopy, 2D FTIR imaging and 3D FTIR micro-tomography (FTIR-μCT) on tannin-furanic rigid foams obtained by varying the synthesis parameters in a controlled way. Thanks to the implementation of the acquisition and processing pipeline of FTIR-μCT, we were able for the first time to demonstrate that the polymer formulations influence the spatial organization of the foam at the microscale and, at the same time, prove the reliability of FTIR-μCT data by comparing 2D FTIR images and the projection of the 3D chemical images on the same plane

Study of the spatio-chemical heterogeneity of tannin-furanic foams: from 1D FTIR spectroscopy to 3D FTIR micro-computed tomography

Tannin-furanic rigid foams are bio-based copolymers of tannin plant extract and furfuryl alcohol, promising candidates to replace synthetic insulation foams, as for example polyurethanes and phenolics, in eco-sustainable buildings thanks to their functional properties, such as lightness of the material and fire resistance. Despite their relevance as environmental-friendly alternatives to petroleum derivatives, many aspects of the polymerization chemistry still remain unclear. One of the open issues is on the spatial heterogeneity of the foam, i.e., whether the foam constituents prevalently polymerize in spatially segregated blocks or distribute almost homogenously in the foam volume. To address this matter, here we propose a multiscale FTIR study encompassing 1D FTIR spectroscopy, 2D FTIR imaging and 3D FTIR micro-tomography (FTIR-\ub5CT) on tannin-furanic rigid foams obtained by varying the synthesis parameters in a controlled way. Thanks to the implementation of the acquisition and processing pipeline of FTIR-\ub5CT, we were able for the first time to demonstrate that the polymer formulations influence the spatial organization of the foam at the microscale and, at the same time, prove the reliability of FTIR-\ub5CT data by comparing 2D FTIR images and the projection of the 3D chemical images on the same plane

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films.

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH3NH3I) and methylammonium bromide (CH3NH3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH3NH3PbX3 with X = I, Br, Cl and their mixture) films with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH3NH3PbI3-xBrx by exposing the substrate to vapors of a mixture of CH3NH3I and CH3NH3Br at reduced pressure and 120 °C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH3NH3PbI3-xBrx with 0 ≤ x ≤ 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV ≤ Eg ≤ 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH3NH3PbI3-xClx. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox

Tannin-furanic foams used as biomaterial substrates for SERS sensing in possible wastewater filter applications

Simple substrates for surface enhanced Raman spectroscopy (SERS), producible in a cost-efficientway, are of growing interest both for scientific and for environmental applications. In this study,we demonstrate the use of three types of bio-based tannin-furanic rigidfoams asprecursormaterials forSERSsubstrates. Coated with a silver layer, these substrates allowed the detection of several well-knownanalytes in themM regime by Raman spectroscopy. Specific optimization of the standard tannin-furanic foammorphology by tuning the chemical synthesis led to a smaller and more homogeneously distributed pore structure, supplyingmoreactivehot spot areas.Thus,we obtained a significant increase and a lower relative standard deviation (RSD) of the SERS signal recorded over themapped SERS substrate area, for several analytes, in particular forMalachite Green dye.Thiswork represents a feasibility study opening several potential applications of this biopolymers in fields such as the detection of water pollutants, virtually combining filtration and SERS capabilities driven by a controlled porosity