H2O Precursor Research Articles

Atomic layer deposited protective coating of aluminum oxide on silver-based telescope mirror: a comparison between a pure ozone and H2O precursor

Atomic layer deposited protective coating of aluminum oxide on silver-based telescope mirror: a comparison between a pure ozone and H2O precursor

Magnetic Nanoparticles with On-Site Azide and Alkyne Functionalized Polymer Coating in a Single Step through a Solvothermal Process.

Background/Objectives: Magnetic Fe3O4 nanoparticles (MNPs) are becoming more important every day. We prepared MNPs in a simple one-step reaction by following the solvothermal method, assisted by azide and alkyne functionalized polyethylene glycol (PEG400) polymers, as well as by PEG6000 and the polyol β-cyclodextrin (βCD), which played a crucial role as electrostatic stabilizers, providing polymeric/polyol coatings around the magnetic cores. Methods: The composition, morphology, and magnetic properties of the nanospheres were analyzed using Transmission Electron and Atomic Force Microscopies (TEM, AFM), Nuclear Magnetic Resonance (NMR), X-ray Diffraction Diffractometry (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), Matrix-Assisted Laser Desorption/Ionization (MALDI) and Vibrating Sample Magnetometry (VSM). Results: The obtained nanoparticles (@Fe3O4-PEGs and @Fe3O4-βCD) showed diameters between 90 and 250 nm, depending on the polymer used and the Fe3O4·6H2O precursor concentration, typically, 0.13 M at 200 °C and 24 h of reaction. MNPs exhibited superparamagnetism with high saturation mass magnetization at room temperature, reaching values of 59.9 emu/g (@Fe3O4-PEG6000), and no ferromagnetism. Likewise, they showed temperature elevation after applying an alternating magnetic field (AMF), obtaining Specific Absorption Rate (SAR) values of up to 51.87 ± 2.23 W/g for @Fe3O4-PEG6000. Additionally, the formed systems are susceptible to click chemistry, as was demonstrated in the case of the cannabidiol-propargyl derivative (CBD-Pro), which was synthesized and covalently attached to the azide functionalized surface of @Fe3O4-PEG400-N3. Prepared MNPs are highly dispersible in water, PBS, and citrate buffer, remaining in suspension for over 2 weeks, and non-toxic in the T84 human colon cancer cell line, Conclusions: indicating that they are ideal candidates for biomedical applications.

Topochemical Modulations from 1D Iron Fluoride Precursor to 3D Frameworks.

Topochemical reactions are powerful pathways to modify inorganic extended structures, but the present approaches are limited by the degrees of freedom to tune the structural connectivity and dimensionality. In this work, we unveil a new topochemical bottom-up approach to tailor three-dimensional (3D) iron fluoride frameworks from the same one-dimensional (1D) FeF3.3H2O (IF) precursor upon reacting with iodide-based reagents (AI; A+ = Na+, K+, and NH4+). To elucidate their formation mechanism, a series of topochemical reactions are performed by varying the concentration of precursors, reaction temperatures, and durations, and their corresponding products are analyzed through X-ray diffraction, nuclear magnetic resonance, and Mössbauer spectroscopy techniques. Although the lower molar ratio of AI:IF (≈0.25:1.0) produces the same hexagonal tungsten bronze (HTB)-type AxFeF3, the topochemical reactions with higher AI:IF ratios yield weberite-Na1.95Fe2F7, tetragonal tungsten bronze (TTB)-K0.58FeF3, and pyrochlore-NH4Fe2F6 phases. Our density functional theory calculations attribute the formation of iron fluoride phases to their thermodynamic stability. Moreover, kinetics also play an important role in enabling weberite and HTB fluorides with high purity, while the pyrochlore-NH4Fe2F6 retains a minor HTB-(NH4)xFeF3 impurity. Overall, this work shows a new possibility of modulating the low-dimensional precursor to attain 3D frameworks with different structural arrangements via topochemical approaches.

Influence of O-H⋅⋅⋅Pt interactions on photoluminescent response in the (Et4N)2{[Pt(bph)(CN)2][phenylene-1,4-diresorcinol]} framework.

Tunable photoluminescence (PL) is one of the hot topics in current materials science, and research performed on the molecular phases is at the forefront of this field. We present the new (Et4N)2[PtII(bph)(CN)2]⋅rez3⋅1/3H2O (Pt2rez3) (bph=biphenyl-2,2'-diyl; rez3=3,3",5,5"-tetrahydroxy-1,1':4',1"-terphenyl, phenylene-1,4-diresorcinol coformer, a linear quaternary hydrogen bond donor) co-crystal salt based on the recently appointed promising [PtII(bph)(CN)2]2- luminophore. Within the extended hydrogen-bonded subnetwork [PtII(bph)(CN)2]2- complexes and rez3 coformer molecules form two types of contacts: the rez3O-H⋅⋅⋅Ncomplex ones in the equatorial plane of the complex and non-typical rez3O-H⋅⋅⋅Pt ones along its axial direction. The combined structural, PL, and DFT approach identified the rez3O-H⋅⋅⋅Pt synthons to be crucial in promoting the noticeable uniform redshift of bph ligand centered (LC) emission compared to the LC emission of the (Et4N)2[PtII(bph)(CN)2]⋅H2O (Pt2) precursor, owing to the direct interference of the phenol group with the PtII-bph orbital system via altering the CT processes within. The high-resolution emission spectra for Pt2 and Pt2rez3 were successfully reproduced at 77 K by using the Franck-Cordon expressions. The possibility to tune PL properties along the plausible continuum of rez3O-H⋅⋅⋅Pt synthons is indicated, considering various scenarios of molecular occupation of the space above and below the complex plane.

Structural and electrochemical properties of LiFePO4 cathode synthesized by solid-state reaction using FeC2O4.2H2O precursor from local Indonesian ilmenite mineral

Structural and electrochemical properties of LiFePO4 cathode synthesized by solid-state reaction using FeC2O4.2H2O precursor from local Indonesian ilmenite mineral

Annealing of ZnO and SnO2 transparent conductive oxides

Transparent Conductive Oxide (TCO) are used in different field [1], especially as antireflective layers on the surface of solar cells [2,3].But in the solar cells process, annealing steps are often used , i.e ; the front metallic contacts of solar cells are obtained by serigraphy at high temperature (800 – 830°C). In this case what happen in TCOs used as antireflective layers ?. In this work we present the comparison of changes in physical properties of two TCOs: tin oxide SnO2 and zinc oxide ZnO when they are annealed at low and high temperatures. These films are deposited by the Atmospheric Pressure Chemical Vapour Deposition APCVD technique. Tin oxide is deposited from tin dichloride (SnCl2, 2H2O) precursor and zinc oxide is obtained by the use of zinc acetylacetonate Zn(C5H7O2)2. The electrical and optical properties of tin oxide and zinc oxide are determined by the four points probes method and spectrophotometry measurement. The values of the resistivity of tin oxide and zinc oxide are 10-4 Ω.cm and 10-3 Ω.cm respectively. These films present an optical transmission higher than 80%. The scanning electronic microscopy images show that the films have a polycrystalline aspect. A post annealing of these TCOs at 450°C improves their electrical properties, while an annealing at higher temperature damage them.

A new method in the production of protective sheets against X-ray radiation

Today, the use of X-rays in diagnosing and sometimes treating patients is inevitable. Despite the many benefits of using X-rays in medical and other sciences, the harmful effects of this radiation on human tissue should not be neglected. One of the best ways to prevent the harmful effects of X-rays on the human body is to use appropriate covers against these rays. It seems that it is necessary to find effective particles to weaken X-rays and choose a suitable substrate with high mechanical resistance to scatter particles in it. In this study, the synthesis of SnO2 nanoparticles from SnCl2.2H2O precursor and BaSO4 nanoparticles from BaCl2.2H2O precursor using neem tree extract (Azadirachta indica) as a reducing and stabilizing agent is reported. After the synthesis of nanoparticles, their structure was investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Then the desired composite and nanocomposite were prepared in the polymer substrate. The sheets were prepared using an extruder and then a hot hydraulic press. The output sheets had a thickness of 1 mm. The structural characteristics of the produced sheets such as surface morphology, density of prepared composites, mechanical properties, thermal gravimetric analysis and retention of loaded particles after three times washes were investigated. The X-ray attenuation capability of each sample was evaluated by calculating the linear attenuation coefficient for each prepared sample. The results show that all sheets filled with tin and barium micro and nano particles have more X-ray attenuation capabilities than pure polymer. Among the prepared sheets, the nanocomposite prepared from low-density polyethylene (77 %) + SnO2 (10 %) + BaSO4 (10 %) + multi-walled carbon nanotubes (3 %) showed the highest X-ray attenuation.

Co-doped cryptomelane-type manganese oxide in situ grown on a nickel foam substrate for high humidity ozone decomposition

Monolithic catalysts with excellent O3 catalytic decomposition performance were prepared by in situ loading of Co-doped KMn8O16 on the surface of nickel foam. The triple-layer structure with Co-doped KMn8O16/Ni6MnO8/Ni foam was grown spontaneously on the surface of nickel foam by tuning the molar ratio of KMnO4 to Co(NO3)2·6H2O precursors. Importantly, the formed Ni6MnO8 structure between KMn8O16 and nickel foam during in situ synthesis process effectively protected nickel foam from further etching, which significantly enhanced the reaction stability of catalyst. The optimum amount of Co doping in KMn8O16 was available when the molar ratio of Mn to Co species in the precursor solution was 2:1. And the Mn2Co1 catalyst had abundant oxygen vacancies and excellent hydrophobicity, thus creating outstanding O3 decomposition activity. The O3 conversion under dry conditions and relative humidity of 65%, 90% over a period of 5 hr was 100%, 94% and 80% with the space velocity of 28,000 hr−1, respectively. The in situ constructed Co-doped KMn8O16/Ni foam catalyst showed the advantages of low price and gradual applicability of the preparation process, which provided an opportunity for the design of monolithic catalyst for O3 catalytic decomposition.

Improved densification in cold sintering of gadolinia‐doped ceria with reactive sintering aids

AbstractThis study explores a novel reactive cold sintering method for improving the density of gadolinia‐doped ceria (GDC) ceramics while reducing the annealing temperature. Instead of using deionized water as an aid in conventional cold sintering, stoichiometrically mixed Ce(NO3)3·6H2O and Gd(NO3)3·6H2O precursors were added as additives during the CSP in this study. The effects of processing parameters such as sintering temperature and additive content on the relative density of the compacts were investigated using synthesized GDC and commercial GDC powders as raw materials. The results showed that with the aid of precursors, GDC ceramics were sintered up to 90% of their theoretical densities at 850°C and up to 94% at 950°C when the synthesized nanopowder GDC was used. Additionally, the sintering mechanism was investigated, and it was found that the GDC generated by the precursor reaction effectively filled the gaps between the original particles, promoting densification of the sample after cold‐pressing.

Solvent-free and efficiently selective oxidation of benzyl alcohol catalyzed by Pd/CeO2 materials under atmospheric oxygen

Selective oxidation alcohol under solvent-free and atmosphere-pressure oxygen is a green and promising strategy for the synthesis of aldehydes and other carboxylic compounds. The design and preparation of efficient heterogeneous catalysts is a hot topic for the process. In this work, CeO2 materials were prepared through a convenient decomposition of Ce(NO3)3·6 H2O precursor, and then employed as supports to load Pd nanoparticles. The decomposition temperature had an important effect on the distributions of Pd0/Pd2+ and Ce3+/Ce4+ species, as well as the oxygen vacancy of Pd/CeO2 materials. In solvent-free and atmosphere-pressure conditions, Pd/CeO2 could smoothly convert benzyl alcohol (BZA) to benzaldehyde (BZL) with oxygen, and the catalytic activity was correlated with the percentage of Pd2+ and oxygen vacancy fractions. Under the reaction time of 4 h, temperature of 90 °C and 4 mL of benzyl alcohol, the conversion of BZA and selectivity to BZL were 72.6% and 96.3%, respectively. The catalyst could be reused at least five times without any significant loss in activity and had no leaching problem of catalytic sites.

Chemistry and microstructure of C-supported Ru catalyst nanoparticles: A correlative study

Ru@Pt core shell nanoparticles possess optimal catalytic properties that facilitate the anodic oxidation reaction of H2 with decreased Pt loading in hydrogen fuel cells. Moreover, since they preferentially oxidize CO, Pt poisoning is considerably reduced, which significantly improves the stability of the cell. The Ru cores used in this system are usually synthesized by dissolving a RuCl3*H2O precursor in an ethylene glycol-carbon black-NaOH mixture. However, the possibility that remnant Cl and Na from the synthesis process are present in the Ru nanoparticles has not been extensively studied.Therefore, due to the challenges in detecting impurities with traditional characterization methods, here correlative atom probe tomography (APT) with scanning transmission electron microscopy ((S)TEM) techniques were implemented. The capabilities of APT to obtain chemical information with high sensitivity at the nanoscale, in combination with the high spatial resolving power of (S)TEM, provide the necessary resolution to fully characterize the structure and chemical makeup of Ru nanoparticles.

Efficient non-fullerene organic solar cells employing aqueous solution-processed MoO3 as a hole-transporting layer

Organic solar cell (OSC) has drawn considerable interest in recent decades owing to their advantages of light weight, flexible, large area and potentially low-cost. Employing an appropriate hole-transporting layer (HTL) into an OSC device has been proved as an efficient method to obtain high efficiency OSC due to the enhancement of the hole transporting and extraction of the device. In this work, aqueous solution-processed MoO3 (s-MoO3) thin films were employed as HTLs to construct non-fullerene PM6:Y6 OSCs. The s-MoO3 thin film was prepared by using an aqueous solution process from an isopolymolybdate [NH4]6Mo7O24.4H2O precursor followed by thermal annealing treatment to convert the precursor to MoO3. The s-MoO3 HTL based PM6:Y6 device demonstrates a power conversion efficiency of 15.75%, which is 38% improved than that of the device with thermally evaporated-MoO3 as HTL and 8% improved than that of the device with PEDOT:PSS as HTL. The enhancement of the device performance could be attributed to the enhanced hole mobility and better band matching of the s-MoO3 HTL. Moreover, the s-MoO3 HTL based PM6:Y6 device exhibited higher device stability than those of the reference devices. Our finding indicates that this s-MoO3 film has great potential as efficient HTL for high performance non fullerene OSCs.

Novel Synthesis of 3D Mesoporous FePO4 from Electroflocculation of Iron Filings as a Precursor of High-Performance LiFePO4/C Cathode for Lithium-Ion Batteries.

This study presents an economic and environmentally friendly method for the synthesis of microspherical FePO4·2H2O precursors with secondary nanostructures by the electroflocculation of low-cost iron fillers in a hot solution. The morphology and crystalline shape of the precursors were adjusted by gradient co-precipitation of pH conditions. The effect of precursor structure and morphology on the electrochemical performance of the synthesized LiFePO4/C was investigated. Electrochemical analysis showed that the assembly of FePO4·2H2O submicron spherical particles from primary nanoparticles and nanorods resulted in LiFePO4/C exhibiting excellent multiplicity and cycling performance with first discharge capacities at 0.2C, 1C, 5C, and 10C of 162.8, 134.7, 85.5, and 47.7 mAh·g-1, respectively, and the capacity of LiFePO4/C was maintained at 85.5% after 300 cycles at 1C. The significant improvement in the electrochemical performance of LiFePO4/C was attributed to the enhanced Li+ diffusion rate and the crystallinity of LiFePO4/C. Thus, this work shows a new three-dimensional mesoporous FePO4 synthesized from the iron flake electroflocculation as a precursor for high-performance LiFePO4/C cathodes for lithium-ion batteries.

Effect of substrate surface on the wide bandgap SnO2 thin films grown by spin coating

Tin (IV) oxide (SnO2) sols have been synthesized from SnCl2·2H2O precursor solution by applying two different processing conditions. The prepared sols were then deposited on UV-Ozone-treated quartz and soda lime glass (SLG) substrates by spin coating. The as-synthesized film was soft baked at about 100 °C for 10 min. This process was repeated 5 times to get a compact film, followed by air annealing at 250 °C for 2 h. The pristine and annealed films were characterized by UV–Vis–NIR spectroscopy, Grazing Incident X-Ray Diffraction (GIXRD), and Field Emission Scanning Electron Microscope (FESEM). The effect of the substrate surface was investigated by measuring the contact angles with De-Ionized (DI) water. UV-Ozone treatment of substrate provides a cleaner surface to grow a homogeneous film. The electrical resistivity of annealed thin films was carried out by a four-point collinear probe employing the current reversal technique and found in the range of ~ 2 × 103 to 3 × 103 Ω·cm. Film thickness was found in the range of ~ 137–285 nm, measured by a stylus profilometer. UV–Vis–NIR transmission data revealed that all the thin-film samples showed maximum (82–89) % transmission in the visible range. The optical bandgap of the thin films was estimated to be ~ 3.75–4.00 eV and ~ 3.78–4.35 eV for the films grown on SLG and quartz substrates, respectively.

The precursors’ feeding ratio of NCQDs/NaBiO3·2H2O induced the modulation of hydrothermal reaction products and their photocatalytic properties

Regulating the composition and proportion of heterojunctions is critical to improve their photocatalytic properties. Many bismuth-based oxides are readily converted from one oxide to another under certain conditions, which supplies a simple strategy for the in-situ construction of bismuth-based oxides heterostructures with controllable composition and proportion. Herein, a series of tunable products from NCQDs/Bi2O4 composite (NCQDs: nitrogen-doped carbon quantum dots) to Bi2O4/Bi2O2CO3 heterojunction to pure Bi2O2CO3 were obtained just by adjusting the NCQDs/NaBiO3·2H2O precursors’ feeding ratio during the hydrothermal process, in which NCQDs act as an active component or carbon source dependant on the feeding ratio. Both NCQDs/Bi2O4 and Bi2O4/Bi2O2CO3 heterostructures exhibit enhanced photocatalytic efficiency for removing methyl orange (MO) and bisphenol A (BPA) under simulated sunlight, compared with Bi2O4 alone. Nevertheless, the latter is more effective in promoting the catalytic activity of Bi2O4 than the former. The reaction rate constant k of the optimal NCQDs/Bi2O4 hybrid is only 1.6 and 2.37 times higher than that of single Bi2O4, whereas the k of the optimal Bi2O4/Bi2O2CO3 heterojunction is about 2.93 and 3.07 times higher than that of single Bi2O4 for the degradation of MO and BPA, respectively. The much higher photoinduced charges’ separation efficiency, verified by the transient photocurrent response and EIS results, should be the main reason the Bi2O4/Bi2O2CO3 heterojunction possesses superior photocatalytic activity to the NCQDs/Bi2O4 heterostructure. Hole (h+) and superoxide radical (•O2−) are determined to be the primary and secondary important active species for the photodegradation reaction, respectively. This work supplies a convenient strategy to modulate the composition and proportion of the hydrothermal reaction products and their photocatalytic properties through changing the precursors’ feeding ratio of NCQDs/NaBiO3·2H2O.

Reactions between SiCl4 and H2O on rutile TiO2 surfaces in atomic layer deposition of SiO2 by first-principles calculations

Atomic layer deposition of SiO2 using SiCl4 and H2O is a classical process, which was initially developed for applications in the field of microelectronics. Recently, it has been demonstrated as an effective surface engineering of nanomaterials in many other applications, including catalysis, pharmaceuticals, and energetic materials. However, fundamental mechanisms of SiO2 film growth at the atomic scale have not been fully understood. In this work, DFT calculations were performed to understand the atomic mechanisms of SiO2 film growth from SiCl4 and H2O precursors on the bare and hydroxylated TiO2 surfaces. Climbing image−nudged elastic band (CI-NEB) method was used to find saddle points and the activation energies for the chemical reactions of several possible mechanisms. The recombination of the by-product HCl with the surfaces and the removal of surface chlorine were also calculated. The results show that SiCl4 can be continuously dissociated on the surface or react with H2O after the first dissociation/ligand exchange reaction. The activation energies from CI-NEB results point out the benefit of the surface hydroxylation in facilitating the initial reaction of SiCl4 on the surface and reducing the production of the adsorbed atomic chlorine as gaseous HCl is released as a by-product. The recombination of the HCl by-product with the surface by either molecular dissociation or ligand exchange reaction with –OH groups can further create atomic chlorine. The removal of the adsorbed chlorine is unlikely, accounting for a certain amount of Cl impurity found by experiments. The calculation results provide an atomic level prediction for designing experimental conditions to achieve desired film quality.

Amorphous Cr2O3 Sheets: A Novel Supercapacitor Electrode Material

AbstractAn ongoing field of study involves improving the performance and stability of benchmarked metal catalysts employing nanostructured non‐metallic materials, which is both fascinating from a fundamental and an application standpoint. By rapidly thermally exfoliating CrCl3 6H2O precursors, amorphous few‐layered nanosheets of Cr2O3 (3‐5 nm) are synthesized. The exfoliated Cr2O3 was characterized using structural and electrochemical techniques. Cyclic Voltammetry (CV) revealed that the material delivers a specific capacitance of 1100 F/g at 10 mV/s, which is among the best‐reported values for this material. This sample has a modest surface area of 155 m2/g with a mesoporous structure. Electrochemical impedance spectra (EIS) for amorphous Cr2O3 revealed lower series resistance (Rs) and charge transfer resistance (Rct) of 0.6 Ω and 0.88 Ω, respectively. Additionally, this material delivers a desirable energy and power density of 20.2 Wh/kg and 125 W/kg, respectively.

Mo–Ag nanocomposite catalysts for the oxygen evolution reaction

Nanocomposite powders are interesting electrocatalysts for efficient water splitting in alkaline medium. In this work, Mo–Ag nanocomposites were prepared by high energy ball milling of (NH4)6Mo7O24.4H2O and AgNO3 precursors, with subsequent reduction in hydrogen atmosphere. High energy ball milling formed spheres composed of needle-like structures of different sizes. The particle size decreases with increasing the milling time from 20 h to 40 h, with the same trend observed for crystallite sizes. The electrochemical performance for the oxygen evolution reaction (OER) is assessed using linear sweep (LSV) and cyclic (CV) voltammetry, electrochemical impedance spectroscopy (EIS), and chronopotentiometry (CP). The values of overpotential, Tafel slope, double layer capacitance (CDL) and turnover frequency (TOF) of samples milled for 20 h and 40 h are determined to be 350 and 330 mV vs. RHE, 84 and 75 mV dec−1, 5.4 and 6.2 mF cm−2, 3.84 × 10−3 and 6.98 × 10−3 mol O2 s−1, respectively, which suggests an improved electrocatalytic activity for the sample milled for 40 h. The increased surface area dramatically boosts the electrochemical processes with adsorbed species. Chronopotentiometry measurements for 15 h reveal that electrodes exhibit acceptable short-term electrochemical stability. The overall results suggest that Mo–Ag nanocomposites are promising materials for the oxygen evolution reaction, being among the best Mo-based electrocatalysts reported in the literature.

Kinetics of TiCl4 Vapor Phase Infiltration (VPI) into PMMA and the Resulting Thermophysical and Optical Properties of the TiOx -PMMA Hybrids

Vapor phase infiltration (VPI) is a post-polymerization modification technique that imbues inorganic materials into polymers to create organic-inorganic hybrid materials with new properties distinct from the parent polymer. While several VPI precursor-polymer chemistries have been explored, a lack of chemical intuition remains for fully understanding the thermodynamics and kinetics that govern the VPI process. This study seeks to continue to build this knowledge by examining the VPI process kinetics for TiO2 infiltration into PMMA via the use of TiCl4 and H2O precursors. In this research, polymethylmethacrylate / TiO2 hybrid materials are prepared using VPI. The depth of infiltration of the TiO2species into ~200 nm PMMA thin films is studied using x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy and spectroscopic ellipsometry. The kinetics for TiCl4 infiltration increases with both VPI process temperature and TiCl4 exposure time. However, the rates of infiltration are considerably slower than those observed in the more commonly studied trimethylaluminum (TMA) / PMMA system. Even at 150 °C, process times of at least 12 hours are required to fully infiltrate a 200 nm PMMA film whereas using TMA similar films are fully infiltrated within 1 hour at the same process temperature. Films that we believe to be fully infiltrated at 150 °C and 24 hours of TiCl4 exposure have a 6 at% Ti in the innermost bulk, as determined by XPS. Interestingly, unlike AlOx-PMMA hybrids, these TiOx – PMMA hybrids exhibit significant changes in their optical properties. Increased titanium loading leads to a 4% increase in refractive index and increased UV absorbance in the UV range of 270-350nm. Furthermore, films infiltrated at 150 °C and 24 hours of TiCl4 exposure had a 50 % and 70 % reduction in coefficients of thermal expansion (CTE) below and above Tg respectively. Reduced CTE trends with increased titanium loading. We will discuss possible opportunities to use these new properties for various applications.This project is supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Sequential Infiltration Synthesis of Al2O3 in Biodegradable Polybutylene Succinate: Characterization of the Infiltration Mechanism.

The introduction of inorganic materials into biopolymers has been envisioned as a viable option to modify the optical and structural properties of these polymers and promote their exploitation in different application fields. In this work, the growth of Al2O3 in freestanding ∼30-μm-thick poly(butylene succinate) (PBS) films by sequential infiltration (SIS) at 70 °C via trimethylaluminum (TMA) and H2O precursors was investigated for the first time. The incorporation of Al2O3 into the PBS matrix was clearly demonstrated by XPS analysis and SEM-EDX cross-sectional images showing a homogeneous Al2O3 distribution inside the PBS films. Raman measurements on infiltrated freestanding PBS show a reduction of the signal related to the ester carbonyl group as compared to pristine freestanding PBS films. Accordingly, FTIR and NMR characterization highlighted that the ester group is involved in polymer–precursor interaction, leading to the formation of an aliphatic group and the concomitant rupture of the main polymeric chain. Al2O3 mass uptake as a function of the number of SIS cycles was studied by infiltration in thin PBS films spin-coated on Si substrates ranging from 30 to 70 nm. Mass uptake in the PBS films was found to be much higher than in standard poly(methyl methacrylate) (PMMA) films, under the same process conditions. Considering that the density of reactive sites in the two polymers is roughly the same, the observed difference in Al2O3 mass uptake is explained based on the different free volume of these polymers and the specific reaction mechanism proposed for PBS. These results assessed the possibility to use SIS as a tool for the growth of metal oxides into biopolymers, paving the way to the synthesis of organic–inorganic hybrid materials with tailored characteristics.