CPMAS NMR Research Articles

Surface modification of aqueous miscible organic layered double hydroxides (AMO-LDHs).

Silane modification of layered double hydroxides (LDHs) plays an important role in controlling the surface hydrophobicity and improving the compatibility of LDHs dispersed in non-polar materials. However, the surface modification of conventional LDHs in hydrous conditions typically results in aggregated particle morphologies, low surface areas and accessible pore volumes. In this study, well dispersed and high surface area silane grafted AMO-Zn2MgAl-CO3 LDH were prepared using the silane coupling agents (triethoxyvinylsilane (TEVS), triethoxyoctylsilane (TEOS) and (3-glycidyloxypropyl)trimethoxysilane (TMGPS)) in anhydrous acetone. Solution 1H NMR spectroscopy was initially used to study the rate and extent of silane reactivity with AMO-Zn2MgAl-CO3 LDH. Powder XRD, TEM, N2 BET specific surface area and total pore volume measurements showed that the structure and morphology of silane-treated AMO-Zn2MgAl-CO3 LDHs remained largely unchanged. Solid state 13C CP-MAS, 27Al DP-MAS and 29Si CP-MAS NMR spectroscopy indicates that the silanes have been successfully grafted onto the surface of the LDH. In addition to maintaining their structure, morphology, high surface area and total pore volume, these surface-functionalised LDHs are now more hydrophobic, displaying a saturation water vapour uptake (<4 wt%) that is ca. 60% lower than the untreated AMO-LDH.

Structure and electrochemical properties of highly conductive and porous carbon nanofiber derived from inclusion complex of cyclodextrin-phenylsilane

A new type of PAN/phenylsilane-based CNF (PPSCD) composite with inclusion complex (IC) is prepared by one-step electrospinning for high-performance electrode materials for supercapacitors. All three cyclodextrin phases (α-CD, β-CD and γ-CD) exhibit different capabilities for the formation of ICs that depend on the size/shape match and binding force between the host CD cavity and the guest molecule of phenylsilane (PS). The effect of the stronger binding and greater interaction of PS in the cavity of α-CD on the morphology and structural properties of the electrospun CNFs are investigated by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and 29Si CP-MAS NMR. The inclusion of small PS molecules is more selective in α-CD, possibly due to stronger binding and greater interaction of PS in the cavity as compared to β- and γ-CD. The PPSα-CD electrode demonstrates superior specific capacitance (173 Fg−1 at a current density of 1 mAcm−2) and high energy density (22.0–8.0 Whkg−1 at power densities ranging from 400 to 10,000 Wk−1) in an aqueous solution. Therefore, the highly conductive PPSα-CD composite provides efficient transport of electrolyte ions and low resistance for charge diffusion in the electrolyte, thereby yielding good capacitive behavior.

Functionalization of silica with amine and ammonium alkyl chains, dendrons and dendrimers: Synthesis and antibacterial properties.

Materials modified with ammonium groups on the surface have shown antibacterial activity. In this paper, alkyl chains, carbosilane (CBS) dendrimers and dendrons and poly(amidoamine) (PAMAM) dendrimers containing amine and ammonium groups have been grafted to silica surface and the influence of molecule structure on the stability and on antibacterial activity have been evaluated. These materials have been characterized by thermogravimetric analysis (TGA), zeta (Z) potential, scanning electron microscopy (SEM), infrared spectroscopy (IR) and nuclear magnetic resonance (13C CP MAS NMR). The degree of silica functionalization depends on type of outer groups, amine or ammonium, type and core of dendrimer, and length of chains. The Z potential measurements of these materials in water suspensions were used to test their stability in this medium. These measurements showed, for some of the modified silicas, the diminishing of Z potential from positive values toward zero, probably due to interaction of the functional groups with the silica surface. This variation was also dependent on ligand structure and peripheral functions. Finally, studies of inhibition of bacteria growth stand out again the relevance of ligand structure and number of functional groups on silica surface. The most active systems were those with more surface covered, those with cationic groups further away from silica surface and higher dendritic generation.

Arsenic(III) Removal by Nanostructured Dialdehyde Cellulose-Cysteine Microscale and Nanoscale Fibers.

Arsenite (As(III)) contamination in drinking water has become a worldwide problem in recent years, which leads to development of various As(III) remediation approaches. In this study, two biomass-based nanostructured materials, microscale dialdehyde cellulose–cysteine (MDAC–cys) and nanoscale dialdehyde cellulose–cysteine (NDAC–cys) fibers, have been prepared from wood pulp. Their As(III) removal efficiencies and mechanism were determined by combined adsorption, atomic fluorescence spectrometry, microscopy (scanning electron microscopy, transmission electron microscopy, and atomic force microscopy), and spectroscopy (Fourier transform infrared, 13C CPMAS NMR) methods. The adsorption results of these materials could be well described by the Freundlich isotherm model, where the maximum adsorption capacities estimated by the Langmuir isotherm model were 344.82 mg/g for MDAC–cys and 357.14 mg/g for NDAC–cys, respectively. Both MDAC–cys and NDAC–cys materials were further characterized by X-ray diffraction and thermogravimetric analysis, where the results indicated that the thiol groups (the S content in MDAC–cys was 12.70 and NDAC–cys was 17.15%) on cysteine were primarily responsible for the adsorption process. The nanostructured MDAC–cys system appeared to be more suitable for practical applications because of its high cost-effectiveness.

Synthesis of mesoporous silica nanoparticles with a lychee-like morphology and dual pore arrangement and its application towards biomimetic activity via functionalization with copper(II) complex

Abstract This work represents the pioneering synthesis of Lychee-like Mesoporous Silica Nanoparticles (LMSN) using a Modified Liquid Template Corrosion (MLTC) method using ethanolamine as a base medium. In this method, the emulsion system containing a cationic surfactant, water, ethylacetate (EA), Tetraethyl orthosilicate (TEOS) was used along-with monoethanolamine under basic conditions. EA was used as the co-template and a swelling agent in the formation of lamellar micelles from spherical and cylindrical micelles. When ethyl acetate (EA) was added to cetyltrimethylammonium bromide (CTAB) and water, initially an oil/water (O/W) mixture was formed due to the formation of lamellar micelles and microemulsion droplets. On addition of ethanolamine, the EA becomes readily hydrolyzed. Then the microemulsion droplets after being corroded serve as templates for the synthesis of mesoporous silica. This method may help us in designing novel nanomaterials in addition to the conventional strategies. The current explorations may afford newer promises towards the well-regulated architecture of silica-based novel materials. The material was then functionalizsed with a novel Schiff base Copper(II) complex and used as a biomimetic catalyst for phenoxazinone synthase mimicking activity which proved to be an efficient one with appreciable yields and good catalytic reusability with negligible leaching. The synthesized materials were characterized by Scanning Electron Microscopy, Energy Dispersive X-Ray analysis(EDAX), Transmission Electron Microscopy, Infrared spectroscopy, X-ray diffraction, nitrogen sorption analyses, 13C CP MAS NMR spectroscopy, TGA, Electron Spin Resonance(ESR) analysis, and ICP-OES studies. A lot more applications could be also anticipated for this morphology.

N-Hydroxysuccinimide-activated esters as a functionalization agent for amino cellulose: synthesis and solid-state NMR characterization

We propose a mild and versatile synthesis protocol based on N-hydroxysuccinimide-activated esters for the introduction of new functionalities to cellulose, using as starting point established protocols for the tosylation of cellulose and its subsequent reaction with a diamine linker. As a proof of concept, we describe the functionalization of microcrystalline cellulose with a N-hydroxysuccinimide-activated ester of benzophenone, a photoreactive functional group. Irradiation of the final product with UV light yields a self-standing polymer film and is expected to result in cross-linking among cellulose chains. To monitor structural changes at the molecular level, each functionalization step is characterized by a multinuclear solid-state NMR approach. DNP-enhanced 15N CP MAS NMR experiments reveal the formation of the amide bond to the photoreactive linker and deliver further information about the binding situation of nitrogen-containing groups in these materials. The flexible synthesis protocol described here can be easily extended to a broad range of other functionalities of interest, both for the cellulose and macromolecular research.

Evaluation of Commercial Humic Substances and Other Organic Amendments for the Immobilization of Copper Through 13C CPMAS NMR, FT-IR, and DSC Analyses

The application of organic amendments to contaminated agricultural lands can immobilize metals and improve soil conditions. The chemical structures and long-term stability of commercial humic substances and other composted organic amendments (sheep and horse manure, vermicompost, pine bark, and pruning waste) were analyzed using 13C CPMAS NMR, FT-IR, and DSC to evaluate their use in soil remediation. The interactions of humic substances and manure with Cu (0 and 5000 mg kg−1) at different pH (2.5 and 5.0) were studied through a batch adsorption experiment observing the changes in their molecular structure using spectroscopic techniques. Humic substances exhibited high aromaticity and phenolic and carboxylic group content, with great affinity for Cu complexation. Humic substances and pruning waste were the most stable due to their high recalcitrant organic matter contents, whereas manure was the least stable, given the labile nature of its organic matter content. There were considerable changes in the carboxylic and phenolic groups of humic substances with pH, and also with Cu, albeit in a lesser extent, especially at pH 5.0, suggesting the great sorption capacity of humic substances and the key role of pH and these functional groups in metal complexation. Manure did not exhibit such changes. Commercial humic substances could be useful amendments for the remediation of contaminated agricultural soils due to their high sorption capacities and long-term stability.

Porous organic polymer derived metal-free carbon composite as an electrocatalyst for CO2 reduction and water splitting

Abstract A hybrid porous organic polymer (POP) comprising of phenylenediamine, phloroglucinol and triazine was synthesized, carbonized at different temperatures and characterized. Solid state 13C and 15N CP-MAS NMR spectra of the POP showed evidences for the presence of the three moieties in varying composition. Raman analysis of the carbonized samples exhibited varying degrees of graphitization and powder X-ray diffraction (PXRD) analysis showed patterns corresponding to N-doped amorphous carbon. Surface morphological characteristics obtained from SEM and TEM analysis confirm different morphologies with slight variations in the particle size and porosity. Further, the electrocatalytic activities of the prepared metal-free catalysts were evaluated. Sample carbonized at 700 °C (PPT-700) showed excellent catalytic activity towards electrocarboxylation of 4-bromoacetophenone in 0.1 M TBABF4/DMF and OER in 1 M KOH as indicated by their onset potential and current density, whereas the sample calcined at 900 °C (PPT-900) exhibited excellent HER activity in 1 M H2SO4. The catalytic activity of PPT-700 towards electrocarboxylation and OER activity is ascribed to the presence of pyridinic, pyrrolic and quaternary nitrogen's, whereas the presence of pyridinic and pyrrolic nitrogen's are responsible for the enhanced HER activity of PPT-900 sample as evident from XPS.

Multifunctional periodic mesoporous benzene-silicas for evaluation of CO2 adsorption at standard temperature and pressure

Abstract Bi-functional periodic mesoporous organosilicas (PMOs) embedded with phenylene- and isocyanurate-bridging groups have been synthesized by a one-pot co-condensation method using 1,4-bis(triethoxysilyl)benzene and tris[3-(trimethoxysilyl)propyl]isocyanurate precursors in the presence of a poly(ethylene oxide)-poly( dl -lactic acid-co-glycolic acid)-poly(ethylene oxide) (PEO-PLGA-PEO) triblock copolymer named LGE54 under acidic conditions. Block copolymer template has been removed by solvent-extraction to get the template-free PMO whereas PLGA block chains from the copolymer template were also removed selectively by thermal treatment at 250 °C retaining PEO chains inside the silica framework. Furthermore, the bi-functional PMO and tri-functional PEO containing PMOs were modified with N-[3-(trimethoxysilyl)propyl]ethylenediamine to prepare amine-coated PMOs on the pore surface. The bi-, tri-, and tetra-functional PMO samples have been thoroughly characterized using small angle X-ray scattering (SAXS) and nitrogen adsorption isotherms to resolve the presence of ordered mesostructure and surface area of the PMOs. Also, solid-state 13C- and 29Si CP-MAS NMR studies have been performed to investigate significant chemical linkages from amine-containing modifiers and poly(ethylene oxide) group inside and on the surface of PMO samples. Scanning electron microscopic (SEM), elemental analysis, and thermogravimetric analysis (TGA) have been carried out to obtain the morphology, elemental percentage and thermal stability of the multi-functional PMO samples, respectively. CO2 capture has been investigated on multi-functional PMO samples at 25 °C and 1 atm using a mixed flow by 3:2 vol ratio of CO2 and N2 gas. Amine-functionalized PMO has shown significantly higher amount of CO2 uptake than those obtained using PMO itself and the respective PMOs modified with different functionalities.

Mineral control of organic carbon storage in acid temperate forest soils in the Basque Country

Soil minerals are known to play a major role in soil organic carbon (SOC) stabilization. However, the exact nature of the role is still poorly understood as comparative studies are complicated by the fact that mineralogy usually varies with other important factors such as climate, land-use, texture and acidity. This study investigated naturally-occurring minerals and C storage in nine mature, second-rotation Pinus radiata D. Don forest plantations at a similar development stage and growing under similar climatic conditions, but established on soils derived from three different parent materials: sandstone, basalt and trachyte. We quantified the SOC stocks in the 0–20 cm soil layer, clay-size minerals and metal oxides. The distribution of SOC in labile and mineral-bound fractions and the chemical structure of the SOC were also determined, by CPMAS NMR spectroscopy. For similar tree biomass, mean SOC storage was 2 times higher in the soils derived from basalt and 2.5 times higher in the soils derived from trachyte which were relatively rich in chlorite/vermiculite mixed layers and short-range order aluminium and iron forms, than in the sandstone-derived soils dominated by illite and with no short-range order aluminium. The parent material also affected the major C components of the SOC. Thus, the proportion of aromatic-C forms in the total SOC was higher in the sandstone-derived soil than in the soils of volcanic origin. Furthermore, the proportion of SOC in the mineral-bound fraction was around 30% in the sandstone-derived soil and around 50% in the volcanic soils. We conclude that estimates of ecosystem SOC stocks in acid temperate forest soils should include proxies for clay mineralogy, such as phyllosilicate minerals, contents of Fe and Al (hydr-) oxides and non-crystalline compounds. In addition, we recommend the inclusion of soil parent material as a proxy in models aimed at estimating regional SOC stocks.

Dialkyldithiocarbamate platinum(II) complexes of [Pt(S2CNR2)2] (R = iso-C3H7, iso-C4H9): Preparation, 13C CP-MAS NMR, molecular structure, supramolecular self-assembly and thermal behaviour

Two new dialkyldithiocarbamato platinum(II) complexes of [Pt(S2CNR)2], R = iso-C3H7 (1) and iso-C4H9 (2), have been prepared and characterised using 13C CP-MAS NMR. The crystal and molecular structures of the isolated compounds were established by single-crystal X-ray diffraction. The unit cell of 1 contains four centrosymmetric discrete molecules of [Pt{S2CN(iso-C3H7)2}2], of which the pairs are structurally inequivalent to each other (hereafter denoted as molecules 1a and 1b). At the supramolecular level, due to numerous intermolecular CH⋯S hydrogen bonds, the 1a molecules form linear polymeric ribbons, whose interaction with the 1b molecules results in a two-dimensional polymeric network. In the structure of 2, the construction of supramolecular zigzag chains by non-centrosymmetric molecules of [Pt{S2CN(iso-C4H9)2}2] is determined by intermolecular CH⋯Pt anagostic interactions. The thermal behaviour of crystalline compounds 1 and 2 was studied by simultaneous thermal analysis (STA), a combination of the TG and DSC techniques, under an argon atmosphere. In both cases, platinum(II) sulfide (PtS) was identified as the main end-product upon thermal decomposition of the complexes at 600 °C.

Principles of the Construction of Polymer Structures, Heteronuclear (13C, 15N) CP-MAS NMR, and Thermal Behavior of Heteroleptic Bismuth(III) Complexes of the General Composition [Bi(S2CNR2)2X] (X = NO3, Cl)

The crystalline heteroleptic bismuth(III) complexes, [Bi{S2CN(iso-C4H9)2}2(NO3)] (I) and [Bi{S2CN(C3H7)2}2Cl] (II), are isolated in preparative yields. Both compounds form 1D polymer structures and are characterized by X-ray diffraction analysis (CIF files CCDC nos. 1877115 (I) and 1876364 (II)) and (13C, 15N) CP-MAS NMR spectroscopy. The coordination mode of each of the dialkyldithiocarbamate ligands is S,S′-anisobidentately terminal. The inorganic anions performing the μ2-bridging function participate in the binding of the adjacent metallic atoms to form zigzag polymer chains. A new mode of bismuth(III) binding involving all oxygen atoms (O,O'-anisobidentate coordination to each adjacent bismuth atom) is found for the bridging nitrate groups in compound I. The bismuth atoms in the studied compounds are characterized by the eightfold [BiS4O4] (I) or sixfold [BiS4Cl2] (II) environment. The thermal behavior of the synthesized complexes is characterized by the data of simultaneous thermal analysis, using parallel recording of thermogravimetry and differential scanning calorimetry curves. In both cases, Bi2S3 is the only final product of the thermal transformations of compounds I and II.

Functionalization of SBA-15 mesoporous materials with 2-acetylthiophene for adsorption of Cr(III) ions

Abstract SBA-15 mesoporous materials functionalized with 2-acetylthiophene-derived Schiff's base denoted as A-SBA-15, were synthesized for removal of Cr(III) ions from aqueous solution. The adsorbent materials were characterized by means of XRD, SEM, TEM, N2 adsorption-desorption, TGA, EDXS, FTIR, 13C CP-MAS NMR and XPS. Tests were then performed to investigate the adsorption of Cr(III) ions onto A-SBA-15 in batch systems. The maximum adsorption capacity of A-SBA-15 (114.2 mg/g) for Cr(III) ions was much higher than that of the pure SBA-15 (15.6 mg/g). The kinetics analysis revealed that the adsorption process was well described by pseudo-second-order kinetic model. In addition, the Langmuir isotherm model was better fitted with the adsorption data for Cr(III) compared to the Freundlich isotherm model. Furthermore, the Cr(III) adsorption onto A-SBA-15 was found to be spontaneous, endothermic, and mainly chemical adsorption as shown by the investigate of various thermodynamic parameters, such as, ΔG°, ΔH°, and ΔS°. The characterization of A-SBA-15 materials before and after adsorption of Cr(III) ions showed that the chemical combination of the organic groups on A-SBA-15 and Cr(III) ions through coordination bond. The as-prepared A-SBA-15 materials could be reused in five successive recycles without significantly decreasing its adsorption capacity. Moreover, four batches of A-SBA-15 prepared at different synthesis times have the similar adsorption capacity. Besides, the adsorbent showed good selective separation of Cr(III) ion in the presence of Cu(II), Zn(II) and Ni(II) ions. The good reproductivity, reusability and selectivity suggest that A-SBA-15 material can be used as a promising adsorbent for efficient removal of heavy metals from aqueous solution.

Chemical Modification of Plasticized Lignins Using Reactive Extrusion.

The reaction of esterification of plasticized Kraft lignin (KL) with succinic and maleic anhydrides using reactive extrusion (REX) was studied in detail. DMSO, glycol and glycerol were found to be efficient plasticizers for lignin. The chemical structure of these new lignin esters was determined using Solid-state 13C CP-MAS NMR and FT-IR analysis. 31P NMR analysis of phosphitylated lignins showed that the aliphatic OH groups of lignin had superior reactivity under the reactive extrusion reaction conditions. The formation of monoesters was confirmed by HSQC NMR spectroscopy. Molecular weight changes after extrusion process were studied using GPC/SEC chromatography. Thermal properties of these polymers were assessed by TGA analysis. The results were compared to lignin esters modified in classical batch conditions. These results show that REX can be used as a new fast, solvent free, and continuous process for lignin valorization.

Immobilization of gold on short-channel mesoporous SBA-15 functionalized with thiol and hydrophobic groups for oxidation reactions

Abstract Nanosized gold entities immobilized on short-channel SBA-15 mesoporous materials functionalized solely with mercaptopropyl groups and together with propyl and octyl moieties have been prepared following a two-steps procedure. These materials have been used as catalysts for the oxidation of cyclohexene with molecular oxygen in liquid phase at atmospheric pressure. First, SBA-15 materials functionalized only with mercaptopropyl groups and with a combination of these groups with two hydrophobic moieties, namely propyl and octyl, have been synthesized in the presence of the non-ionic surfactant P104. Small particles having short channel length have been identified by TEM and SEM. In order to study the influence of the nature of the sulphur functional group, these S-bearing materials were also oxidized with hydrogen peroxide or dimethyldioxirane (DMD) to sulfonic groups prior to gold immobilization. The effectiveness of these oxidation methods was assessed by 29Si MAS NMR, 13C CP MAS NMR, XPS, chemical and thermal analysis, and it has been found that DMD oxidized efficiently thiol groups to sulfonic groups, but H2O2 leaves a fraction of unreacted thiol. In a second step, nanosized gold entities have been prepared by a two-liquid phases route involving rosemary oil as organic phase and an aqueous phase formed by dissolving gold in a solution of ammonium chloride in concentrated nitric acid (aqua regia). Following this method, a fraction of the Au dissolved in the aqua regia solution is spontaneously reduced and transferred to the essential oil phase. Upon contacting the gold-bearing organic layer with the mesoporous materials, gold is actually immobilized on them, rendering metal contents in the range 1.1-0.2 wt.%, being those functionalized with alkyl chains the least efficient in capturing gold from the organic phase. No surface plasmon resonance band at 520 nm characteristic of gold nanoparticles has been detected by UV–vis spectroscopy in these Au-containing materials. All of them are active and selective for the allylic oxidation of cyclohexene, but their specific activity varies as a function of the nature of the functional groups. It has been found that the most active catalysts are those pre-oxidized with DMD. The presence of hydrophobic octyl groups increases substantially the turnover number of the reaction (TON), while the short-chain propyl moieties hardly affect the activity. It has been found that the nanosized gold entities initially present in the catalysts evolve in the reaction medium towards the formation of nanoparticles.

Synthesis of polymer/CNTs composites for the heterogeneous asymmetric hydrogenation of quinolines

The development of heterogeneous catalytic processes is crucial for the synthesis of chiral compounds for both academic and industrial applications. However, thus far, such achievements have remained elusive. Herein, we report the heterogeneous asymmetric hydrogenation of 2-methylquinoline over solid chiral catalysts, which were prepared by the one-pot polymerization of (1R,2R)-N-(4-vinyl-benzenesulfonyl)-1,2-diphenylethane-1,2-diamine (VDPEN) and divinylbenzene (DVB) in the presence or absence of activated carbon (C) or carbon nanotubes (CNTs), followed by Ru coordination and anion exchange. The solid chiral catalysts were fully characterized by N2 sorption analysis, elemental analysis, TEM, FT-IR spectroscopy, and13C CP-MAS NMR. All the solid chiral catalysts could efficiently catalyze the asymmetric hydrogenation of 2-methylquinoline to afford 2-methyl-1,2,3,4-tetrahydroquinoline with 90% ee. Studies have shown that polymer/C and polymer/CNTs composites are more active than pure polymers. The polymer/CNTs composite exhibited the highest activity among all the solid chiral catalysts under identical conditions, owing to the unique morphology of CNTs. The recycling stabilities of the solid chiral catalysts were greatly improved when ionic liquids (ILs) were employed as solvents; this is mainly attributed to the decreased leaching amount of anions owing to the confinement effect of ILs on ionic compounds.

Naked-Eye Heterogeneous Sensing of Fluoride Ions by Co-Polymeric Nanosponge Systems Comprising Aromatic-Imide-Functionalized Nanocellulose and Branched Polyethyleneimine.

Heterogeneous colorimetric sensors for fluoride ions were obtained by cross-linking TEMPO-oxidized cellulose nanofibers (TOCNF) with chemically modified branched polyethyleneimine 25 kDa (bPEI). Functionalization of bPEI primary amino groups with aromatic anhydrides led to the formation of the corresponding mono- and bis-imides on the grafted polymers (f-bPEI). A microwave-assisted procedure allowed the optimization of the synthetic protocol by reducing reaction time from 17 h to 30 minutes. Hydrogels obtained by mixing different ratios of TOCNF, bPEI and f-bPEI were lyophilized and thermally treated at about 100 °C to promote the formation of amide bonds between the amino groups of poly-cationic polymers and the carboxylic groups of cellulose nanofibers. This approach generated a series of cellulose nanosponges S1-S3 which were characterized by FT-IR and by solid state 13 C CPMAS NMR. These sponge materials can act as colorimetric sensors for the selective naked-eye recognition of fluoride ions over chloride, phosphate and acetate ions at concentrations of up to 0.05 M in DMSO. Moreover, when the sponges were functionalized with perylene tetracarboxylic diimide, successful naked-eye detection was achieved with only 0.02 % w/w of chromophore units per gram of material.

3-Arm PEG Based Amphiphilic Polymer Sorbents for Polar and Non-Polar Liquids

Crosslinked polymer gels are gaining technological and industrial attention due to their sophisticated application features. Herein, a highly effective amphiphilic polymeric network capable of absorbing polar and nonpolar solvents was produced using hydrophilic glycerol ethoxylate, a member of star type polyethylene glycol (s-PEG), and different hydrophobic organosilane monomers by bulk polymerization as utilized under an inert atmosphere. In this context, the preparation of amphiphilic polymeric networks was achieved by the reaction between hydroxyl terminated s-PEG and ethoxysilane terminated organosilane without using any initiator, activator or a catalyst. SEM, FTIR, 13C and 29Si CPMAS NMR and TGA are used for morphological, structural and thermal characterization of the prepared materials. Likewise, the absorption behavior of amphiphilic polymeric networks was determined by measuring their swelling ratios in polar and nonpolar solvents. Because of having a hydrophobic and hydrophilic structure in their 3D polymeric structure, the obtained polymeric networks behave as an organogel in oil medium, while they can prepared as a hydrogel in aqueous medium. The effect of crosslinker’s difference on the swelling capacity of sorbent were researched by comparing different molecular weight of monomers, and it was found that the molecular structure of organosilane monomers had significant influence on the swelling ability of obtained amphiphilic sorbents. By the use of easy preparations, not needing extra agents for the synthesis, having high and quick absorption abilities in organic solvents showed that the resulting amphiphilic sorbent have potential as absorbents for different organic solvents. Also, the degradable features of amphiphilic polymer networks in water open up optimum application opportunities for additional uses, such as with drug delivery agents.

Application of Comprehensive Multiphase NMR To Characterize Organic Matter in Clay and Atmospheric Particulates

The molecular composition of organic matter (OM) and its interaction with minerals play important roles in regulating the fate of carbon and pollutants in soil and in the atmosphere. Clay minerals such as montmorillonite processed with bacteria can imitate the microbial interactions occurring in more complex natural environmental media such as soil and atmospheric particulates. Here, we characterize OMs in multiple phases for bacteria-inoculated montmorillonite clay and atmospheric particulates collected in China. In addition to the traditional 13C cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) experiments, this study, for the first time, applies both one- and two-dimensional comprehensive multiphase (CMP) NMR to these critical environmental issues. The CMP NMR experimental spectra show that the main OM components in these samples are aliphatics, carbohydrates, and aromatics. These CMP NMR spectra also reveal the biochemical interactions between microbes and clay minerals by identifying the metabolites. CMP NMR can further investigate the states, interfacial/surficial interactions, and dynamics at the molecular/atomic levels since diffusion/relaxation (T2)-edited experiments can distinguish OM with differing sizes and mobilities. Therefore, the mechanism at the atomic/molecular level for environmental biogeochemical interactions can be efficiently probed by CMP NMR experiments. This paper concludes that CMP NMR is a powerful and innovative tool for crucial environmental studies at the molecular/atomic scale, providing not only the composition, phase, and structural identifications but also the interfacial/surficial interaction dynamics involved in environmental geochemical processes.

Characterization of Handmade Papers (13th–15th century) from Camerino and Fabriano (Marche, Italy)

The dispute over the paternity of western paper is a longstanding problem. In Italy, a country that has a long tradition of papermaking, many cities compete for the leadership in the production of this material; on the other hand, several studies attribute to Fabriano (13th century), a little center in Marche region, the birth of modern paper and its diffusion throughout Europe. During the 14thcentury, the nearby town of Camerino imposed itself on the paper market, triggering a historic rivalry with the manufacture of Fabriano. As scientific studies on these different productions are missing, a comparative, multidisciplinary investigation has been carried out to characterize a set of thirteenth-fifteenth century handmade papers from Camerino-Fabriano area. Several analytical techniques–some non-invasive such as Fourier-transform infrared spectroscopy (FTIR) and portable magnetic resonance (unilateral NMR), joined to micro-destructive ones such as scanning electron microscopy (SEM), 13C CPMAS NMR spectroscopy, thermo-gravimetric analysis (TGA), sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and reverse-phase liquid chromatography (RP-HPLC)–have been employed in order to study the morphology of the paper documents, to identify the substances used in production process and to define their preservation state. Moreover principal component analysis (PCA) has been applied to the spectroscopic data, allowing the clustering of Fabriano documents with respect to Camerino ones and dividing the samples in two sets. This work improves and confirms knowledges on paper production in Marche region, and the experimental data collected highlight similarities and differences between Camerino and Fabriano manufactures.