Proton-conducting Organic-inorganic Sulfo-containing Membranes for Fuel Cell

Cross-linked organiс-inorganic sulfo-containing membranes of various compositions based on acrylic monomers (acrylonitrile, acrylic acid, 3-sulfopropylacrylate potassium salt, ethylene glycol diacrylate) and sol-gel systems of tetraethoxysilane have been developed. Synthesis of the polymer matrix was carried out by UV-initiated polymerization of the monomer mixture and the inorganic component was formed in situ while conducting the sol-gel process of the precursor. FTIR, SEM, EDS, DMA, impedance spectroscopy were used to characterize the synthesized materials. The influence of inorganic component content on the properties of the membranes was investigated. DMA results show that an increase in silica content leads to a decrease in packing density and an increase in structural heterogeneity in sulfo-containing polyacrylate/silica membranes. The highest values of proton conductivity 1.12 ꞏ 10−2 Sm/cm at 60 °C were found in membranes containing 3 wt.%. of the added sol-gel system. Further increase of silica content does not increase the proton conductivity of the membranes. The proton transfer activation energies in the membranes were calculated from the temperature dependence of proton conductivity. The obtained cross-linked sulfo-containing organic-inorganic materials can be used for the development of proton-conducting membranes for fuel cells.

PHYSICAL AGING OF ORGANO-INORGANIC NANOCOMPOSITES BASED ON POLYIMIDE WITH CARD SUBSTITUENTS

The physical aging was investigated of obtained by sol-gel technology nanocomposites based on polyimide (PI) with card substituents and tetraethoxysylane (TEOS). The results for organic-inorganic composites, that contain of 5%. 20% or 50 % of TEOS, demonstrate that at temperatures well below (400K) the glass transition temperature of the polymer can take place changes in the dynamic characteristics of polymer macrochains and its permeability to low molecular probe as well as changes in aggregation of inorganic component. According to the methods of EPR, optical microscopy, etc. changes that occur in the characteristics of sol-gel polyimide based nanocomposites during long-term storage at temperatures much lower than the glass transition temperature of the polymer can be described as follows. The segmental mobility of the organic component is significantly reduced and the dynamic heterogeneity of the polymer increases. The decrease in the relative permeability of aged nanocomposites with increased content of inorganic component as compared with aged pure PI does not correlate with the content of TEOS in contrast to the initial samples of the same composition. PI macrochains chemically bonded to the inorganic phase have limited ability to realize an optimal conformation in the process of thermal relaxation (physical aging) so the increasing the content of the inorganic component has less effect on reducing the permeability of aged composites compared to aged pure PI. This is consistent with changes in the distribution of inorganic aggregates of composites. There are changes in the mean size of aggregates of inorganic particles in the composite and a decrease in their number. Smoothing is observed of the surface of nanocomposite films as well as disappearance of inhomogeneities caused by the surface of support. Due to the chemical bonding of inorganic particles and polyimide matrix, the peculiarities of the physical aging process of such composites are due to the mutual influence of the inorganic and polymer components.

Effect of Poly(Titanium Oxide) on the Viscoelastic and Thermophysical Properties of Interpenetrating Polymer Networks

The influence of poly(titanium oxide) obtained using the sol-gel method in 2-hydroxyethyl methacrylate medium on the viscoelastic and thermophysical properties of interpenetrating polymer networks (IPNs) based on cross-linked polyurethane (PU) and poly(hydroxyethyl methacrylate) (PHEMA) was studied. It was found that both the initial (IPNs) and organo-inorganic interpenetrating polymer networks (OI IPNs) have a two-phase structure by using methods of dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The differential scanning calorimetry methods and scanning electron microscopy (SEM) showed that the presence of poly(titanium oxide) increases the compatibility of the components of IPNs. It was found that an increase in poly(titanium oxide) content leads to a decrease in the intensity of the relaxation maximum for PHEMA phase and an increase in the effective crosslinking density due to the partial grafting of the inorganic component to acrylate. It was shown that the topology of poly(titanium oxide) structure has a significant effect on the relaxation behavior of OI IPNs samples. According to SEM, a uniform distribution of the inorganic component in the polymer matrix is observed without significant aggregation.

Assessment of Naturally Sourced Mineral Clays for the 3D Printing of Biopolymer-Based Nanocomposite Inks

The present study investigated the possibility of obtaining 3D printed composite constructs using biomaterial-based nanocomposite inks. The biopolymeric matrix consisted of methacrylated gelatin (GelMA). Several types of nanoclay were added as the inorganic component. Our aim was to investigate the influence of clay type on the rheological behavior of ink formulations and to determine the morphological and structural properties of the resulting crosslinked hydrogel-based nanomaterials. Moreover, through the inclusion of nanoclays, our goal was to improve the printability and shape fidelity of nanocomposite scaffolds. The viscosity of all ink formulations was greater in the presence of inorganic nanoparticles as shear thinning occurred with increased shear rate. Hydrogel nanocomposites presented predominantly elastic rather than viscous behavior as the materials were crosslinked which led to improved mechanical properties. The inclusion of nanoclays in the biopolymeric matrix limited hydrogel swelling due the physical barrier effect but also because of the supplementary crosslinks induced by the clay layers. The distribution of inorganic filler within the GelMA-based hydrogels led to higher porosities as a consequence of their interaction with the biopolymeric ink. The present study could be useful for the development of soft nanomaterials foreseen for the additive manufacturing of customized implants for tissue engineering.

Luminescent Ionogels with Excellent Transparency, High Mechanical Strength, and High Conductivity

The paper describes a new kind of ionogel with both good mechanical strength and high conductivity synthesized by confining the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([Bmim][NTf2]) within an organic–inorganic hybrid host. The organic–inorganic host network was synthesized by the reaction of methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), and methyl methacrylate (MMA) in the presence of a coupling agent, offering the good mechanical strength and rapid shape recovery of the final products. The silane coupling agent 3-methacryloxypropyltrimethoxysilane (KH-570) plays an important role in improving the mechanical strength of the inorganic–organic hybrid, because it covalently connected the organic component MMA and the inorganic component SiO2. Both the thermal stability and mechanical strength of the ionogel significantly increased by the addition of IL. The immobilization of [Bmim][NTf2] within the ionogel provided the final ionogel with an ionic conductivity as high as ca. 0.04 S cm−1 at 50 °C. Moreover, the hybrid ionogel can be modified with organosilica-modified carbon dots within the network to yield a transparent and flexible ionogel with strong excitation-dependent emission between 400 and 800 nm. The approach is, therefore, a blueprint for the construction of next-generation multifunctional ionogels.

Determination of the Content of Iodine in a Nut Corner by Pyrolysis in the Temperature Range 100-550°C

The article presents the results of scientific research on the processing of nutshells by the pyrolysis method. The process of pyrolysis of walnut shells in the temperature range of 100–550 °C with the formation of charcoal without air was studied. The inorganic component in the shell is about 25%, while the organic part is 75%. It was found that the yield of charcoal from the walnut shell is 31.3% by weight at 550 °C, and the iodine concentration is 0.105 μg/dm3.

Fluorescent SiO2@Tb3+(PET-TEG)3Phen Hybrids as Nucleating Additive for Enhancement of Crystallinity of PET

A hybrid polymer of SiO2@Tb3+(poly(ethylene terephthalate)-tetraglycol)3 phenanthroline (SiO2@Tb3+(PET–TEG)3Phen) was synthesized by mixing of inorganic SiO2 nanoparticles with polymeric segments of PET–TEG, whereas PET–TEG was achieved through multi-step functionalization strategy. Tb3+ ions and β-diketonate ligand Phen were added in resulting material. The experimental results demonstrated that it was well blended with PET as a robust additive, and not only promoted the crystallinity, but also possessed excellent luminescence properties. An investigation of the mechanism revealed that the SiO2 nanoparticles functioned as a crystallization promotor; the Tb3+ acted as the fluorescent centre; and the PET–TEG segments played the role of linker and buffer, providing better compatibility of PET matrix with the inorganic component. This work demonstrated that hybrid polymers are appealing as multifunctional additives in the polymer processing and polymer luminescence field.

The Inorganic Component as a Possible Marker for Quality and for Authentication of the Hazelnut’s Origin

The inorganic component of hazelnuts was considered as a possible marker for geographical allocation and for the assessment of technological impact on their quality. The analyzed samples were Italian hazelnuts of the cultivar Tonda Gentile Romana and Turkish hazelnuts of the cultivars Tombul, Palaz and Çakildak. The hazelnuts were subjected to different drying procedures and different conservative methods. The concentration of 13 elements, namely Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, P, Sn, Sr and Zn, were quantified by inductively coupled plasma optical emission spectroscopy (ICP-OES). All the samples were previously digested in a microwave oven. Before proceeding with the analysis of the samples, the whole procedure was optimized and tested on a certified reference material. The results show that the inorganic component: (i) can represent a fingerprint, able to identify the geographical origin of hazelnuts, becoming an important quality marker for consumer protection; (ii) is strongly influenced by the treatments undergone by the investigated product during all the processing stages. A pilot study was also carried out on hazelnuts of the cultivar Tonda Gentile Trilobata Piemontese, directly harvested from the plant during early development to maturity and analyzed to monitor the element concentration over time.

Leaching mechanism of bioapatite in carbonate-saturated water

Bioapatite, the main inorganic component of bone, is similar to hydroxyapatite (HAp, Ca5[PO4]3(OH)) having some [CO3]2− content which plays an important role in leaching/precipitation processes in many biological lesions.