Drd. Eng. Andreea ANDRONE

In this work a method in two steps for the preparation of the composites based on poly(ortho-toluidine) (POT) and the MoS2 and WS2 sheets was reported. In the first step, by ball-milling of mixtures of MoS2 and WS2 particles, the sheets of MoS2 and WS2 (MoS2: WS2) with weight ratio equal to 3:1, 1:1 and 1:3 were prepared. In the second step, the interaction in solid-state of the MoS2: WS2 samples with POT in emeraldine-base (POT-EB) and emeraldine-salt (POT-ES) was used to obtain composites of the type MoS2: WS2/POT-EB and MoS2: WS2/ POT-ES. Using X-ray diffraction (XRD), FTIR spectroscopy, Raman scattering and X-ray photoelectron spectroscopy (XPS), we demonstrate that: i) the ball-milling method can allow the preparation of the MoS2 and WS2 sheets with different stacking order, ii) the interaction of POT-EB with the MoS2: WS2 samples involves the transformation of some repeating units of the type EB into ES; and iii) the interaction of POT-ES with the MoS2: WS2 samples leads to the appearance of new positive charges onto macromolecular chains which are compensated by S2- ions. According to thermogravimetric analysis (TG) and differential scanning calorimetry (DSC), all samples are demonstrated to be stable up to 230 degrees C. Dielectric spectroscopy data reveal a complex dependence of DC electrical conductivity on frequency, temperature, and composite concentration. We use the apparent activation energy, defined as the derivative of the logarithm of conductivity with respect to the inverse temperature. The obtained results indicate that apparent activation energy is influenced by system composition via filling factors. The electrical properties of these heterogeneous materials are described using Lichtenecker's mixing laws. For components with similar electrical properties, the effective conductivity and apparent activation energy were determined as linear combinations of the individual conductivities and activation energies, respectively, weighted by the component concentrations. Our findings align with experimental data, offering a framework for understanding conductivity and activation energy in multi-component systems.

In this work, three methods for the synthesis of composites based on poly(ortho-toluidine) (POT) and WS2 are reported: (a) the solid-state interaction (SSI) of POT with WS2 nanoparticles (NPs); (b) the in situ chemical polymerization (ICP) of ortho-toluidine (OT); and (c) the electrochemical polymerization (ECP) of OT. The preparation of WS2 sheets was performed by the ball milling of the WS2 NPs followed by ultrasonication in the solvent N,N'-dimethyl formamide. During the synthesis of the POT/WS2 composites by SSI and ICP, an additional exfoliation of the WS2 NPs was reported. In this work, we demonstrated the following: (a) the ICP method leads to POT/WS2 composites, which contain repeating units of POT in the leucoemeraldine salt (LS) state, while (b) the ECP method leads to POT/WS2 composites, which contain repeating units of POT in the emeraldine salt (ES) state. Capacitances equal to 123.5, 465.76, and 751.6 mF cm-2 in the cases of POT-ES/WS2 composites, synthesized by SSI, ICP, and ECP, respectively, were reported.

In this work, applications of nanohybrid composites based on titanium dioxide (TiO2) with anatase crystallin phase and single-walled carbon nanohorns (SWCNHs) as promising catalysts for the photodegradation of amoxicillin (AMOX) are reported. In this order, TiO2/SWCNH composites were prepared by the solid-state interaction of the two chemical compounds. The increase in the SWCNH concentration in the TiO2/SWCNH composite mass, from 1 wt.% to 5 wt.% and 10 wt.% induces (i) a change in the relative intensity ratio of the Raman lines located at 145 and 1595 cm(-1), which are attributed to the E-g(1) vibrational mode of TiO2 and the graphitic structure of SWCNHs; and (ii) a gradual increase in the IR band absorbance at 1735 cm(-1) because of the formation of new carboxylic groups on the SWCNHs' surface. The best photocatalytic properties were obtained for the TiO2/SWCNH composite with a SWCNH concentration of 5 wt.%, when approx. 92.4% of AMOX removal was achieved after 90 min of UV irradiation. The TiO2/SWCNH composite is a more efficient catalyst in AMOX photodegradation than TiO2 as a consequence of the SWCNHs' presence, which acts as a capture agent for the photogenerated electrons of TiO2 hindering the electron-hole recombination. The high stability of the TiO2/SWCNH composite with a SWCNH concentration of 5 wt.% is proved by the reusing of the catalyst in six photodegradation cycles of the 98.5 mu M AMOX solution, when the efficiency decreases from 92.4% up to 78%.

In this paper we present the results obtained by depositing the nanocomposite materials based on nano TiO2/TiO2:N, Ag, SiO2, single-walled carbon nanotube (SWCNTs), single-walled functionalized carboxylic acid, (SWCNT-COOH), poly(2,2' bithiophene) (PBTh) and poly(dipheylamine) (PDPA) by conventional and unconventional methods on the surface of sheepskin leathers. The nanocomposite materials were integrated in film forming polymers and were applied on sheepskin leather surfaces by spraying (conventional method) or by activating the surface with cold atmospheric plasma followed by electrospraying (unconventional methods). The leather surfaces were tested for antimicrobial properties against Grampositive and Gram-negative bacteria and fungi according to ISO 20743: 2007. The photocatalytic properties under visible light exposure were also tested using two organic stain models (methylene blue and orange II). The stain discoloring was evaluated by measuring the color differences between the blank and the samples with DATA Color Check Plus II portable device assisted by CIELab color management software. The evaluation of the physical-mechanical resistance and comfort properties for the sheepskin leathers was determined by measuring the water vapor permeability, rubbing tests and abrasion resistance. The results showed that the sheepskin leather surfaces treated with nanocomposite materials have improved antibacterial, self-cleaning, physical-mechanical and comfort properties as compared to untreated samples, with potential applications for added value multifunctional products. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conferences & Exhibition on Nanotechnologies, Organic Electronics & Nanomedicine - NANOTEXNOLOGY 2020. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/

The effect of UV light on the cationic photopolymerization of the SU8 negative photoresist is shown by photoluminescence (PL) studies. Our results demonstrate that the cationic photopolymerization reaction of the SU8 photoresist takes place predominantly under the influence of the UVA light. Using UVA light, the influence of carbon nanotubes [of the types single-walled carbon nanotubes (SWNTs), double-walled carbon nanotubes (DWNTs), multiwalled carbon nanotubes (MWNTs), and SWNTs functionalized with carboxyl groups (SWNTs-COOH)] on the cationic photopolymerization process of the SU8 photoresist is shown by PL studies. The cationic photopolymerization of the SU8 photoresist is monitored by the variations of the two emission bands with maxima at similar to 400-429 nm and 523-556 nm. The increase in the relative intensity of the PL band at similar to 523-556 nm is dependent on (i) the carbon nanotube concentration in the SU8 photoresist matrix; (ii) the type of carbon nanotubes, i.e., SWNTs, DWNTs, and MWNTs; and (iii) the nonfunctionalized and functionalized state of SWNTs. The results reported in this work demonstrate that PL can be used as a complementary method to Raman scattering and IR spectroscopy in the investigation of the cationic photopolymerization reaction of the SU8 negative photoresist. A decrease in the wrapping angle of carbon nanotubes with the SU8 photoresist is highlighted by anisotropic PL studies.