The syntheses of five propargylated dendrimer scaffolds ranging from 2, 3, 4, 6, and 12 surface groups are described together with a 2-azidoethyl α-D-mannopyranoside. The former is appended to the core structure using highly efficient copper-catalysed azide-alkyne cycloaddition (CuAAC) (“click reaction”) to provide glycodendrimers in an accelerated approach. Two of the core structures are based on cyclotrisphosphazene, thus expanding the scope of the “onion-peel” strategy to build dendritic architectures with a large number of surface groups at the G1 generation only.

Spherical particles are routinely monitored and described by hydrodynamic diameters determined, e.g., by light scattering techniques. Non-spherical particles such as prolate ellipsoids require alternative techniques to characterize particle size as well as particle shape. In this study, oligo(ε-caprolactone) (oCL) based micronetwork (MN) particles with a shape-shifting function based on their shape-memory capability were programmed from spherical to prolate ellipsoidal shape aided by incorporation and stretching in a water-soluble phantom matrix. By applying light microscopy with automated contour detection and aspect ratio analysis, differences in characteristic aspect ratio distributions of non-crosslinked microparticles (MPs) and crosslinked MNs were detected when the degrees of phantom elongation (30-290%) are increased. The thermally induced shape recovery of programmed MNs starts in the body rather than from the tips of ellipsoids, which may be explained based on local differences in micronetwork deformation. By this approach, fascinating intermediate particle shapes with round bodies and two opposite sharp tips can be obtained, which could be of interest, e.g., in valves or other technical devices, in which the tips allow to temporarily encage the switchable particle in the desired position.

In this work, green nanotechnology has been applied by using phytochemical compounds as reducing agents from the plant extract of Hydrocotyle ranunuculoides through three modifications of the phytosynthesis method to prepare Fe and Zn nanoparticles, in three different concentration of the metallic solution. In the third modification a MgO support was included to avoid the Fe and Zn NP agglomeration. The nanoparticles size was 5±1 nm, and for the Fe NPs, it was determined with a cubic structure a Fe3O4 composition, and Zn nanoparticles were obtained with a hexagonal structure and Zn° composition. In the third method, MgO nanoparticle, the support appears as Mg0 nanoparticles surrounded by Fe0 and Zn0 nanoparticles. According to the three used methods pathways, the main influence is the modification in the method synthesis. Hybrid nanocomposites provide a means in preventing agglomeration of the NPs and hence avoid coalescence and loss of properties.

The present study investigated the adsorption of fluorides in natural zeolites clinoptilolite-type, sourced in Sonora, Mexico, and modified with Fe. Characterization of the material was carried out along with determination of kinetic parameters varying time and concentration of reagents to calculate maximum adsorption capacity. To determine thermodynamic parameters temperature was varied for accurate characterization of the adsorption process. It was found that the zeolite fixed Fe in its structure without model significant modification, likewise when put in contact with a fluoride solution (F-), it was capable of taking up these ions through adsorption due to the interaction between the sorbato and the pollutant. The kinetics best fit Pseudo-second-order model with Qmax=0.91 mgg-1, therefore it indicates that the process is reversible, spontaneous and endothermic what can favor the reuse of the material.

We synthesized precision oligomers of thiophene with cationic and hydrophobic side chains to mimic the charge, hydrophobicity, and molecular size of antibacterial host defense peptides (HDPs). In this study, the source of cationic charge was a guanidinium salt moiety intended to reflect the structure of arginine-rich HDPs. Due to the pi-conjugated oligo(thiophene) backbone structure, these compounds absorb visible light in aqueous solution and react with dissolved oxygen to produce highly biocidal reactive oxygen species (ROS). Thus, the compounds exert bactericidal activity in the dark with dramatically enhanced potency upon visible light illumination. We find that guanylation of primary amine groups enhanced the activity of the oligomers in the dark but also mitigated their light-induced activity enhancement. In addition, we also quantified their toxicity to mammalian cell membranes using a hemolysis assay with red blood cells, in the light and dark conditions.

Thin polythiophene films were prepared by electrodeposition, using two novel thiophene monomers containing a pyrene unit linked via a flexible spacer. The obtained polymers have a suitable architecture for the further preparation of polymer composites with graphene via π-π interactions. Physicochemical characterization of the precursor polymers demonstrated that the resulting films are made of homogeneous electroactive polythiophene with pendant pyrene units regularly located on the polymer surface. These compounds are highly emissive and easily form excimers as other high pyrene content polymers. The polymer emission can be drastically quenched by the interaction with graphene after dipping the film into an aqueous suspension of reduced graphite oxide. The presence of aggregated graphene onto pyrene rich content areas by non-covalent interactions has been confirmed by AFM analysis. This kind of polythiophene/pyrene thin films showed to be a good matrix for the elaboration of fluorescent polymer composites.

In this work, the synthesis of starch-clay nanocomposites was carried out. For this purpose, natural starch was extracted from rice grains and it was characterized by structural and spectrophotometric techniques. Afterwards, it was used as the polymer matrix for the synthesis of nanocomposites crosslinked with different agents: glycerol, citric acid (CA) and sodium trimetaphosphate (STMP). As a reinforcement phase, a natural Mexican clay from the Montmorillonite-type (Mt), was employed, which was modified with a cationic surfactant, hexadecyltrimethylammonium bromide (HDTMA-Br), in order to exchange cations, present in the interlaminar spaces of the raw clay mineral with those of the cationic surfactant; thus, changing its nature from hydrophilic to hydrophobic. Characterization, of both natural and organo-modified clays, was carried out by means of scanning electron microscopy (SEM), to determine the change in morphology between these two minerals; X-ray diffraction analysis (XRD), to obtain the crystalline structure of the organo-modified clay and that of the raw clay mineral (Mt). Also, the Fourier transform infrared spectroscopy (FTIR) was employed to determine materials spectra, and their thermal stability was evaluated by means of the thermogravimetric analysis (TGA). On the other hand, the synthesis of these nanocomposites was performed using different crosslinking agents, glycerol, CA or STMP, in order to identify the effect of them into the final properties of these materials.

In this study, silver, zinc and copper nanoparticles, AgNPs, ZnNPs and CuNPs, were tested on photodegradation using phenol as a model contaminant. The nanoparticles were phytosynthesized from an aqueous extract of Eichhornia crassipes leaves, and were characterized by UV-visible spectroscopy, EDS (Dispersive Energy X-ray Spectroscopy), SEM (Scanning Electron Microscopy), and TEM (Transmission Electron Microscopy). The AgNPs, ZnNPs and CuNPs showed a characteristic plasmon determined by UV-Vis; in the case of the EDS analyses Ag, Zn and Cu were detected as the main components. The detected composition by TEM corresponded to a metallic oxide for the three nanoparticles. Finally, for the photocatalytic performance on the phenol degradation under UV radiation, they showed about 50%, 52% and 34% with a 10 mg/L phenol solution that was achieved within 200 min using AgNPs, ZnNPs and CuNPs, respectively.

The implantation and controlled release of growth factors can enhance the proliferation and differentiation of cells that promote new bone formation at defect sites. Therefore, chitosan polymer microspheres were prepared by the water-in-oil emulsion (W/O) method and solvent freeze-drying, using glutaraldehyde as an ionic crosslinker, along with the lyophilization of solvents, to microencapsulate growth factors, preventing denaturation. The microspheres were loaded with recombinant bone morphogenetic protein 2 (Rh-BMP-2). They were spherical in shape, with a rough surface ranging in particle size from 0.4 to 1.6 μm. The yield percentage with respect to the polymer was 70% and the BMP-2 load was regulated by the initial protein dose. BMP-2 release experiments were performed for 7 days in PBS solutions at pH 4 and 7.4. The results showed that the protein release rate was only 2% lower at pH 7.4. BMP-2/chitosan microspheres were compatible with the MG-63 cell line (ATCC®CRL-1427™Homo sapiens bone osteosarcoma) and could be considered drug delivery vehicles in bone tissue engineering applications.

Chitosan (Ch)-Polyvinyl (alcohol) (PVA) hydrogels cross-linked with sodium tripolyphosphate were synthetized to obtain a polymer matrix encapsulating an insecticide (active ingredient: imidacloprid). Imidacloprid release tests were performed separately with moist and lyophilized hydrogel beads with a diameter of 3.47 and 3.30 mm respectively. The concentration of the insecticide released in the medium was determined by UV-Visible spectroscopy, reaching equilibrium for wet hydrogels at 72h at a concentration of 330 mg L-1 and 281 mg L-1 in 48h for lyophilized hydrogels, comparing it with a maximum load of 330.18 mg L-1of imidacloprid contained in the hydrogels. The characterization of hydrogels was performed by Fourier transform infrarred spectroscopy (FTIR) to determine the functional groups. The morphology of the polymer matrix of the hydrogels was carried out in a scanning electron microscope (SEM). The size distribution and diameter of bead samples were observed through a stereomicroscope. The percentage of humidity of the hydrogels was determined obtaining 94.8% once the imidacloprid was released. the pore size of the samples was determined by the Brunauer-Emmet-Teller (BET) technique. The techniques used indicated that controlled release of imidacloprid could be more efficient with wet hydrogels in relation to the maximum load of imidacloprid contained, for protection of crops is necessary for a long time because of insecticide disponible in the soil.

The catalyst ZeoSonFe(M1), mixed with hydrogen peroxide and UV light, presented the highest degradation percent within 120 minutes of treatment respect to ZeoSonFe(M2), ZeoSonFe(M3) and ZeoSonFe(M4) which accounted for 72.92, 84.27, and 72.30 %, respectively. The spectrum of UV-Vis degradation showed that the absorption main bands of IC (612 and 286 nm) decrease due to the rupture of C=C bond that belong to the chromophorous group IC. The catalyst ZeoSonFe(M1) was characterized with infrared (FTIR), Scanning Electron Microscopy (SEM) and pore diameter analysis with the BET method. To describe the kinetics of the oxidative reaction the pseudo first order model was applied.

The aim of this investigation was to study castor, canola, and sesame vegetable oils in order to evaluate their potential use as lubricants in steel mechanical components. For this purpose, densities of each oil were evaluated using the pycnometer method, as well as their dynamic viscosities through a Brookfield DV-II rotational viscometer. Both properties were evaluated at temperatures of 25, 40 and 100 °C. Additionally, viscosity indexes were determined according to ASTM D 2270. These rheological properties were used to estimate the lubrication regime considering parameters of real contact conditions in mechanical components. Friction and wear analyses were carried out to investigate the behaviour of the vegetable oil as lubricants. Such tests were carried out at room temperature on a CSM tribometer with pin-on-disk configuration by using castor, canola and sesame oils as lubricants. AISI 4140 hardened steel against AISI 100Cr6 steel pin was used as a mechanical component. From the rheological study, it was observed that canola and sesame oils behave as dilatant fluids at the evaluated temperatures, while castor oil behaves like a Newtonian fluid at 25 and 40 °C. Castor oil showed the highest density value among oils studied, but it also exhibited the lowest value of viscosity index (271). Contrarily, sesame oil was the least dense, but it exhibited the highest viscosity index (545). On the other hand, the lubrication regime study showed that by using castor oil as a lubricant in the mechanical component (4140/100Cr6), the system worked in a mixed lubrication regime while by using canola and sesame oils the system operated in boundary lubrication conditions. Finally, the kinetic friction coefficients were different for each lubricant obtaining the lowest value with castor oil while the highest value of friction coefficient was exhibited by the sesame oil lubricant.

The precise control of curing reaction parameters allows a better crosslinking polymer. Modelling and optimization of this process require a correct kinetic of curing model. The kinetics of the crosslinking reaction is studied for the ethylene propylene diene monomer (EPDM) synthetic elastomer by mobile die rheometer (MDR). The kinetic parameters of reaction were calculated from Kamal-Ryan, Sestak-Berggren, and the Isayev-Deng methods at different temperatures. An Arrhenius-type function for the order of reaction n is introduced to improve the adjusting. Finally, a graphical and analytical description of the cure kinetics was developed. The order of reaction is predicted to better establishment of processing time. It was noted that for EPDM at higher temperatures, the increase of the rate of reaction occurs in short period of time, which could cause premature curing if the supply system is inadequate.

Polypyrrole (PPy) thin films were synthetized by plasma and simultaneously doped with Iodine to enhance electromagnetic absorption and charge transfer capability in a resistive coupling cylindrical reactor. Pyrrole monomer and Iodine were the principal reagents used and the chemical reactions were created by high frequency plasma. Micrographs show an irregular surface formed by semi-spherical protrusions with tiny particles in the PPy/I samples and a rather smooth surface with wrinkles and less participation of tiny particles to PPy ones. Infrared spectroscopy analysis reveals important absorption peaks at 3253, 2932, 1668 and 635 cm-1 corresponding to the chemical bonds N-H and C-H, C-H aliphatic, C=C and C-I, respectively, belonging to the chemical structure of Pyrrole. Electrical conductivity of PPy increased from 10-10 to 10-8 S/cm due to Iodine doping. Electromagnetic absorption showed a higher response between 340 and 800 nm in the visible region. Activation energy was calculated in the range from -0.09 to 0.49 eV.