Aurica Farcas - Academia.edu (original) (raw)
Papers by Aurica Farcas
Materials
Two poly(3,4-ethylenedioxythiophene) polyrotaxanes (PEDOT∙TMe-βCD and PEDOT∙TMe-γCD) end-capped b... more Two poly(3,4-ethylenedioxythiophene) polyrotaxanes (PEDOT∙TMe-βCD and PEDOT∙TMe-γCD) end-capped by pyrene (Py) were synthesized by oxidative polymerization of EDOT encapsulated into TMe-βCD or TMe-γCD cavities with iron (III) chloride (FeCl3) in water and chemically characterized. The effect of TMe-βCD or TMe-γCD encapsulation of PEDOT backbones on the molecular weight, thermal stability, and solubility were investigated in depth. UV–vis absorption, fluorescence (FL), phosphorescence (PH), quantum efficiencies, and lifetimes in water and acetonitrile were also explored, together with their surface morphology and electrical properties. Furthermore, dynamic light scattering was used to study the hydrodynamic diameter (DH) and z-potential (ZP-ζ) of the water soluble fractions of PEDOT∙TMe-βCD and PEDOT∙TMe-γCD. PEDOT∙TMe-βCD and PEDOT∙TMe-γCD exhibited a sharp monodisperse peak with a DH of 55 ± 15 nm and 122 ± 32 nm, respectively. The ZP-ζ value decreased from −31.23 mV for PEDOT∙TMe-...
Materials
New composite materials were prepared via cross-linking of polyethylene glycol/2-hydroxypropyl-β-... more New composite materials were prepared via cross-linking of polyethylene glycol/2-hydroxypropyl-β-cyclodextrins polyrotaxane (PEG/HPβCD) and polyisoprene/HPβCD semi-polyrotaxane (PI/HPβCD SR) with 1,6-hexamethylene diizocyanate (HMDI). Advanced instrumental methods (such WAXS (wide angle X-ray scattering), AFM (atomic force microscopy), SEM (scanning electron microscopy), and thermal and dynamic vapor sorption) were employed for the structural, morphological and thermal characterization of the resulting composite materials. The roughness parameters calculated using AFM indicate a smoother surface for the composite material with 10 wt% of PI/HPβCD SR, denoting that a homogeneous film was obtained. SEM analysis reveals porous morphologies for both composite materials and the pore sizes increase with the increasing concentration of PI/HPβCD SR in the matrix. Dynamic vapor sorption/desorption measurements and type IV isotherms confirmed the hydrophilic and porous materials, which are in ...
Phosphorus, Sulfur, and Silicon and the Related Elements, 2019
This work deals with the effect of chemical structure and iodine doping on electro-optical charac... more This work deals with the effect of chemical structure and iodine doping on electro-optical characteristics of different polysilanes in the solid state. The properties of polymethylphenylsilane homopolymer were compared with those of polysilane copolymers containing diphenylsilylene structural units associated with either methylhydrogen-or methylphenylsilylene moieties. Their optical parameters, such as Urbach energy and optical band gap, were evaluated using the method proposed by Tauc. The forbidden gap values for the studied polysilanes are reduced after doping from 3.22-3.46 eV to 2.47-2.64 eV, while the electrical conductivities were found in the range of 6.2 10 À11-1.2 10 À8 S/cm for pristine samples, and increased by 2-3 orders of magnitude following their doping, depending on the nature/content of the organic substituents attached to the silicon main chain. A simple mathematical approach starting from Tauc classical theory was used to establish allowed direct optical transitions for both undoped and doped polysilane samples. The obtained data indicated that the polysilane films with a high content of phenyl side groups presented the best properties for their use in electro-optical applications.
e-Polymers, 2006
This paper is devoted to the preparation and characterization of new phenanthroline-triether copo... more This paper is devoted to the preparation and characterization of new phenanthroline-triether copolymers with rotaxane architecture by reaction of complexes of α- or β- cyclodextrin and tri(ethylene glycol) ditosylate with 2,9-di(4-hydroxyphenyl)-1,10- phenanthroline, which is large enough to prevent dethreading of cyclodextrin molecules. Comparative
Polymer Bulletin, 1994
The synthesis of three Schiff-base type monomers containing pyrrole units was performed. Their po... more The synthesis of three Schiff-base type monomers containing pyrrole units was performed. Their polymerization was carried out by chemical oxidation with (NH4)2S208. Some preliminary thermal and electrical properties were determined.
![Research paper thumbnail of Effect of Rotaxane Formation on the Photophysical, Morphological, and Adhesion Properties of Poly[2,7-(9,9-dioctylfluorene)-alt -(5,5'-bithiophene)] Main-Chain Polyrotaxanes](https://attachments.academia-assets.com/106695081/thumbnails/1.jpg)
](Macromolecular Chemistry and Physics, 2011
Effect of Rotaxane Formation on the Photophysical www.mcp-journal.de UEFISCSU, project number PNI... more Effect of Rotaxane Formation on the Photophysical www.mcp-journal.de UEFISCSU, project number PNII-IDEI cod 998/2008, and SENAN code 12-109/2008. IG and WMN would like to thank the Deutsche Forschungsgemeinschaft (DFG, NA 686/6) and the Fonds der Chemischen Industrie for financial support. AF thanks the ICTS program and the Center for Functional Materials and Nano-molecular Science (NanoFun) at Jacobs University for supporting a research stay. Helpful cooperation with Dr. Nathalie Jarroux (from the Universitite d'Evry, France) is acknowledged.
Journal of Polymer Science Part A: Polymer Chemistry, 2009
Skip to Main Content. ...
[
European Polymer Journal, 2014
ABSTRACT Poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene/permethylated β-cyclodextrin) (3·PM... more ABSTRACT Poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene/permethylated β-cyclodextrin) (3·PMeβCD) main-chain polyrotaxane was synthesized according to a Suzuki-type aryl-aryl coupling protocol, by reacting 9,9-dioctylfluorene-2,7-trimethylene diborate (1) with an inclusion complex of 5,5′-dibromo-2,2′-bithiophene (2)/permethylated-βCD (PMeβCD) (2·PMeβCD). The complexation ability of PMeβCD molecule towards monomer 2 was confirmed by MM+ and PM3 quantum-mechanics semi-empirical methods, ESI-MS, (ESI) MS/MS analysis, as well as FTIR and 1H-NMR spectroscopy. A conjugated polyrotaxane copolymer with PMeβCD/structural unit ratio of about 1/3 and the number average molecular weight (Mn) value of 30600 was obtained by 1H-NMR spectroscopy and gel permeation chromatography, respectively. The thermal, optical, surface morphology and the adhesion characteristics were investigated and compared to those of the non-rotaxane counterpart poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene) (3).
Chemical Physics …, 2011
... OF - CYCLODEXTRIN AZOMETHINE [2]-ROTAXANE FORMATION BY SEMI-EMPIRICAL METHOD PM3 Aurica Farca... more ... OF - CYCLODEXTRIN AZOMETHINE [2]-ROTAXANE FORMATION BY SEMI-EMPIRICAL METHOD PM3 Aurica Farcas a*1 , Adrian Fifere a , Iuliana Stoica a , Flavian Farcas b , Ana-Maria Resmerita aa P. Poni Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley ...
Chemical Physics Letters, 2014
ABSTRACT The effect of oligoazomethines (OA) encapsulation into the cavity of permethylated α-cyc... more ABSTRACT The effect of oligoazomethines (OA) encapsulation into the cavity of permethylated α-cyclodextrin on the electro-optical properties was investigated. The polyrotaxane (OA-Rot) formation leads to distinct improvements in the solubility and film forming ability, as well as photophysical and morphological properties, compared with OA unthreaded analogues. The 2D and 3D AFM images of the OA-Rot film showed a smoother and uniform surface. In addition, the HOMO/LUMO energy levels, as well as the energy band gap of OA-Rot are slightly lower than OA counterpart. As expected, doping of the rotaxane structures with iodine showed a smaller enhancement of the electrical conductivity.
Applied Catalysis A: General, 2013
Abstract Poly(1-butene) low molecular weight macromolecules with molecular weights within 1000–20... more Abstract Poly(1-butene) low molecular weight macromolecules with molecular weights within 1000–20,000 g mol −1 and isotacticities around 50–90% were prepared by the polymerization of 1-butene in liquid phase with n-butane as solvent using two metallocene catalysts: rac-dimethyl-silyl-bis-(2-methyl-4,5-benzoindenyl)zirconium dichloride (A) and rac-dimethyl-silyl-bis-(2-methylindenyl)zirconium dichloride (B). Catalyst A showed higher yields and productivities than catalyst B, as well as better isotacticity values, which were ascribed to the presence of an additional aryl substituent in the indenyl moiety which increases its stability and hinders deactivation phenomena by aggregation. Kinetic experiments with catalyst A showed a continuous increase in conversion along the time so no strong deactivation was observed. With catalyst A, an increase in the hydrogen pressure at 75 °C up to 6.0 bar led towards low molecular weight macromolecules with 3000–4000 g mol −1 and a isotacticity of 75–80%. An enhancement in temperature up to 105 °C decreased the yields, molecular weights and isotacticity for both catalysts. Additionally, increasing the hydrogen partial pressure to 1.0 bar at 95 and 105 °C decreased the molecular weight within the 3000–5500 g mol −1 range. XRD patterns of the majority of low molecular weight macromolecules showed the presence of mixed phases, although some low molecular weight macromolecules with pure phase I (twined hexagonal) were obtained. Additionally, the DSC thermograms showed a decrease in the melting temperatures of the crystalline phases of poly(1-butene) low molecular weight macromolecules with regard to the corresponding ones of poly(1-butene) polymers ( M w > 100,000 g mol −1 ), due to their lower molecular weight.
The present manuscript reports an overview of the design and conceptual approaches to the synthes... more The present manuscript reports an overview of the design and conceptual approaches to the synthesis of rotaxaconjugated polymers (R-CP), such as aromatic polyazomethines, alternating or random polyfluorene copolymers encapsulated inside native CD cavities. Their synthesis correlated with an overview of the photophysical properties, surface morphology and electrochemical behaviours, which are advantageous for the generation of active layers in organic electronic devices, are considered in this review.
Molecules
Herein, we report the synthesis of inclusion complexes (ICs) based on 3,4-ethylenedioxythiophene ... more Herein, we report the synthesis of inclusion complexes (ICs) based on 3,4-ethylenedioxythiophene (EDOT) with permethylated β-cyclodextrins (TMe-βCD) and permethylated γ-cyclodextrins (TMe-γCD) host molecules. To prove the synthesis of such ICs, molecular docking simulation, UV-vis titrations in water, 1H-NMR, and H-H ROESY, as well as matrix-assisted laser desorption ionization mass spectroscopy (MALDI TOF MS) and thermogravimetric analysis (TGA) were carried out on each of the EDOT∙TMe-βCD and EDOT∙TMe-γCD samples. The results of computational investigations reveal the occurrence of hydrophobic interactions, which contribute to the insertion of the EDOT guest inside the macrocyclic cavities and a better binding of the neutral EDOT to TMe-βCD. The H-H ROESY spectra show correlation peaks between H-3 and H-5 of hosts and the protons of the guest EDOT, suggesting that the EDOT molecule is included inside the cavities. The MALDI TOF MS analysis of the EDOT∙TMe-βCD solutions clearly rev...
Beilstein Journal of Organic Chemistry, 2012
The paper reports the preparation of a poly[2,7-(9,9-dioctylfluorene)-alt-5,5'-bithiophene/PS... more The paper reports the preparation of a poly[2,7-(9,9-dioctylfluorene)-alt-5,5'-bithiophene/PS-βCD] (PDOF-BTc) polyrotaxane copolymer, through a Suzuki coupling reaction between the 5,5'-dibromo-2,2'-bithiophene (BT) inclusion complex with persilylated β-cyclodextrin (PS-βCD), and 9,9-dioctylfluorene-2,7-bis(trimethylene borate) (DOF) as the blocking group. The chemical structure and the thermal and morphological properties of the resulting polyrotaxane were investigated by using NMR and FT-IR spectroscopy, TGA, DSC and AFM analysis. The encapsulation of BT inside the PS-βCD cavity results in improvements in the solubility, as well as in different surface morphology and thermal properties of the PDOF-BTc rotaxane copolymer compared to its noncomplexed PDOF-BT homologue. In contrast, the number-average molecular weight (Mn) of PDOF-BTc rotaxane copolymer indicated lower values suggesting that the condensation reaction is subjected to steric effects of the bulkier silylated...
Lubrication aspects, in extreme operating conditions, highlights important problems concerning be... more Lubrication aspects, in extreme operating conditions, highlights important problems concerning bearings design or greases behaviour management for given operating conditions. The researches that were done in the last period were focused on greases service life and behaviour versus rolling bearings operating conditions but, it must be emphasized, that some particular aspects such as the presence of the electrical fields were less studied. Some results in this specific area were previously forwarded by Prashad who highlighted issues such as greases resistivity modifications with time, particular bearings and lubricating greases damaging mechanisms. Aspects concerning temperature influence on grease resistivity, correlations between greases structural, physical and chemical deterioration and bearings specific failures, in the presence of the electrical field, are questions that must be answered. These problems are very important because electrical rotating machines support bearings reliability is strongly dependant on greases service life and performances. The paper presents some correlations between the electrical field characteristics and electrical motors rotors support rolling bearings greases deterioration based on lubricant's SEM and raceways microscopical analyses. Starting from these results it can be concluded that rolling bearings deterioration under the influence of the electrical field is a complex phenomenon with effects, both, on lubricating greases and bearings rolling contact surfaces. From this point, a greases deterioration model, in the presence of the electrical field, will be proposed.
2021 13th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2021
Research activity is packed with a lot of different systems, having different degrees of complexi... more Research activity is packed with a lot of different systems, having different degrees of complexity, interrelated, that have to multitask on multiple leveles, exchange data, collaborate, to achieve the best results in the shortest / optimal time. In order to have a successfully implemented research activity, a system have to be: reliably engineered - that is to function failure free for a given time interval, stable - for a controled interval of values given at input a stable system produces a controled interval of values at output, and not in the end, a quality implementation of the solution [1]. The ultimate goal is to significantly increase the performance, amongst other things by having errors, human and otherwise, less and less present, through the proposed system we constructed where the HPLS will achieve the status of being ”AI and robotically managed”. We integrate, modify, adapt, customize various equipment and make them work best together within our designed architecture - nothing more, nothing less, nothing else. A series of important activities are and can be very time consuming - need to speed up - automate! To release resources towards imagination, creativity, ideas, solutions [1].
Langmuir, 2021
In the present study, we investigated the effect of permodified 2,3,6-tri-O-trimethylsilyl β- and... more In the present study, we investigated the effect of permodified 2,3,6-tri-O-trimethylsilyl β- and γ-cyclodextrin (TMS·β-CD, TMS·γ-CD) encapsulation on the optical, electrochemical, morphological, and supramolecular arrangements of a poly[2,7'-(9,9-dioctylfluorene-alt-2',7-fluorene)] PF copolymer. For this purpose, the photophysical properties and Langmuir monolayer formation of PF·TMS·β-CD and PF·TMS·γ-CD polyrotaxanes were investigated and compared with those of the reference PF. Surface pressure-area isotherms and Brewster angle microscopy studies indicated the capability of both polyrotaxanes to organize into larger and homogeneous 2D supramolecular assemblies at the air-water interface. The obtained results suggest that the presence of the surrounding TMS·β-CD and TMS·γ-CD macrocycles on the PF backbones leads to changes in the conformation and hydrophobicity of the film surfaces. Our investigation offers a method to assess the impact of TMS-CD encapsulation on the control of 2D monolayer formation, with particular attention on the generation of stable PF monolayers for organic electronic devices.
![Research paper thumbnail of Polyrotaxanes based on PEG-amine with cucurbit[7]uril, α-cyclodextrin and its tris-O-methylated derivative](https://attachments.academia-assets.com/104331783/thumbnails/1.jpg)
](European Polymer Journal, 2017
Cucurbit[7]uril (CB7), native -cyclodextrin (αCD) and its tris-O-methylated derivative (TMαCD) a... more Cucurbit[7]uril (CB7), native -cyclodextrin (αCD) and its tris-O-methylated derivative (TMαCD) as macrocyclic host molecules and amine-terminated poly(ethylene glycol) (PEG) as neutral guest were used for the synthesis of 3-CB7, 3-αCD and 3-TMαCD polyrotaxanes. The binding affinities of the neutral PEG guest into the CB7, CD and TMαCD cavities were evaluated by isothermal titration calorimetry. The high value of the stability constant (1 × 10 4 M −1) indicates that PEG provides a preferential binding to CB7 over CD. The polyrotaxane structure was confirmed by FT-IR and 1 H NMR spectroscopy. The coverage ratio of the PEG with CB7, αCD and TMαCD macrocycles, were 63%, 71%, and 30%, respectively. The polyrotaxanes 3-CB7 and 3-αCD exhibit an enhancement in thermal stability compared with the non-rotaxane 3 counterpart. In addition, polyrotaxane 3-CB7 shows blue-shifted absorption by more than 20 nm and enhanced water solubility.
Materials
Two poly(3,4-ethylenedioxythiophene) polyrotaxanes (PEDOT∙TMe-βCD and PEDOT∙TMe-γCD) end-capped b... more Two poly(3,4-ethylenedioxythiophene) polyrotaxanes (PEDOT∙TMe-βCD and PEDOT∙TMe-γCD) end-capped by pyrene (Py) were synthesized by oxidative polymerization of EDOT encapsulated into TMe-βCD or TMe-γCD cavities with iron (III) chloride (FeCl3) in water and chemically characterized. The effect of TMe-βCD or TMe-γCD encapsulation of PEDOT backbones on the molecular weight, thermal stability, and solubility were investigated in depth. UV–vis absorption, fluorescence (FL), phosphorescence (PH), quantum efficiencies, and lifetimes in water and acetonitrile were also explored, together with their surface morphology and electrical properties. Furthermore, dynamic light scattering was used to study the hydrodynamic diameter (DH) and z-potential (ZP-ζ) of the water soluble fractions of PEDOT∙TMe-βCD and PEDOT∙TMe-γCD. PEDOT∙TMe-βCD and PEDOT∙TMe-γCD exhibited a sharp monodisperse peak with a DH of 55 ± 15 nm and 122 ± 32 nm, respectively. The ZP-ζ value decreased from −31.23 mV for PEDOT∙TMe-...
Materials
New composite materials were prepared via cross-linking of polyethylene glycol/2-hydroxypropyl-β-... more New composite materials were prepared via cross-linking of polyethylene glycol/2-hydroxypropyl-β-cyclodextrins polyrotaxane (PEG/HPβCD) and polyisoprene/HPβCD semi-polyrotaxane (PI/HPβCD SR) with 1,6-hexamethylene diizocyanate (HMDI). Advanced instrumental methods (such WAXS (wide angle X-ray scattering), AFM (atomic force microscopy), SEM (scanning electron microscopy), and thermal and dynamic vapor sorption) were employed for the structural, morphological and thermal characterization of the resulting composite materials. The roughness parameters calculated using AFM indicate a smoother surface for the composite material with 10 wt% of PI/HPβCD SR, denoting that a homogeneous film was obtained. SEM analysis reveals porous morphologies for both composite materials and the pore sizes increase with the increasing concentration of PI/HPβCD SR in the matrix. Dynamic vapor sorption/desorption measurements and type IV isotherms confirmed the hydrophilic and porous materials, which are in ...
Phosphorus, Sulfur, and Silicon and the Related Elements, 2019
This work deals with the effect of chemical structure and iodine doping on electro-optical charac... more This work deals with the effect of chemical structure and iodine doping on electro-optical characteristics of different polysilanes in the solid state. The properties of polymethylphenylsilane homopolymer were compared with those of polysilane copolymers containing diphenylsilylene structural units associated with either methylhydrogen-or methylphenylsilylene moieties. Their optical parameters, such as Urbach energy and optical band gap, were evaluated using the method proposed by Tauc. The forbidden gap values for the studied polysilanes are reduced after doping from 3.22-3.46 eV to 2.47-2.64 eV, while the electrical conductivities were found in the range of 6.2 10 À11-1.2 10 À8 S/cm for pristine samples, and increased by 2-3 orders of magnitude following their doping, depending on the nature/content of the organic substituents attached to the silicon main chain. A simple mathematical approach starting from Tauc classical theory was used to establish allowed direct optical transitions for both undoped and doped polysilane samples. The obtained data indicated that the polysilane films with a high content of phenyl side groups presented the best properties for their use in electro-optical applications.
e-Polymers, 2006
This paper is devoted to the preparation and characterization of new phenanthroline-triether copo... more This paper is devoted to the preparation and characterization of new phenanthroline-triether copolymers with rotaxane architecture by reaction of complexes of α- or β- cyclodextrin and tri(ethylene glycol) ditosylate with 2,9-di(4-hydroxyphenyl)-1,10- phenanthroline, which is large enough to prevent dethreading of cyclodextrin molecules. Comparative
Polymer Bulletin, 1994
The synthesis of three Schiff-base type monomers containing pyrrole units was performed. Their po... more The synthesis of three Schiff-base type monomers containing pyrrole units was performed. Their polymerization was carried out by chemical oxidation with (NH4)2S208. Some preliminary thermal and electrical properties were determined.
Macromolecular Chemistry and Physics, 2011
Effect of Rotaxane Formation on the Photophysical www.mcp-journal.de UEFISCSU, project number PNI... more Effect of Rotaxane Formation on the Photophysical www.mcp-journal.de UEFISCSU, project number PNII-IDEI cod 998/2008, and SENAN code 12-109/2008. IG and WMN would like to thank the Deutsche Forschungsgemeinschaft (DFG, NA 686/6) and the Fonds der Chemischen Industrie for financial support. AF thanks the ICTS program and the Center for Functional Materials and Nano-molecular Science (NanoFun) at Jacobs University for supporting a research stay. Helpful cooperation with Dr. Nathalie Jarroux (from the Universitite d'Evry, France) is acknowledged.
Journal of Polymer Science Part A: Polymer Chemistry, 2009
Skip to Main Content. ...
[
European Polymer Journal, 2014
ABSTRACT Poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene/permethylated β-cyclodextrin) (3·PM... more ABSTRACT Poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene/permethylated β-cyclodextrin) (3·PMeβCD) main-chain polyrotaxane was synthesized according to a Suzuki-type aryl-aryl coupling protocol, by reacting 9,9-dioctylfluorene-2,7-trimethylene diborate (1) with an inclusion complex of 5,5′-dibromo-2,2′-bithiophene (2)/permethylated-βCD (PMeβCD) (2·PMeβCD). The complexation ability of PMeβCD molecule towards monomer 2 was confirmed by MM+ and PM3 quantum-mechanics semi-empirical methods, ESI-MS, (ESI) MS/MS analysis, as well as FTIR and 1H-NMR spectroscopy. A conjugated polyrotaxane copolymer with PMeβCD/structural unit ratio of about 1/3 and the number average molecular weight (Mn) value of 30600 was obtained by 1H-NMR spectroscopy and gel permeation chromatography, respectively. The thermal, optical, surface morphology and the adhesion characteristics were investigated and compared to those of the non-rotaxane counterpart poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene) (3).
Chemical Physics …, 2011
... OF - CYCLODEXTRIN AZOMETHINE [2]-ROTAXANE FORMATION BY SEMI-EMPIRICAL METHOD PM3 Aurica Farca... more ... OF - CYCLODEXTRIN AZOMETHINE [2]-ROTAXANE FORMATION BY SEMI-EMPIRICAL METHOD PM3 Aurica Farcas a*1 , Adrian Fifere a , Iuliana Stoica a , Flavian Farcas b , Ana-Maria Resmerita aa P. Poni Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley ...
Chemical Physics Letters, 2014
ABSTRACT The effect of oligoazomethines (OA) encapsulation into the cavity of permethylated α-cyc... more ABSTRACT The effect of oligoazomethines (OA) encapsulation into the cavity of permethylated α-cyclodextrin on the electro-optical properties was investigated. The polyrotaxane (OA-Rot) formation leads to distinct improvements in the solubility and film forming ability, as well as photophysical and morphological properties, compared with OA unthreaded analogues. The 2D and 3D AFM images of the OA-Rot film showed a smoother and uniform surface. In addition, the HOMO/LUMO energy levels, as well as the energy band gap of OA-Rot are slightly lower than OA counterpart. As expected, doping of the rotaxane structures with iodine showed a smaller enhancement of the electrical conductivity.
Applied Catalysis A: General, 2013
Abstract Poly(1-butene) low molecular weight macromolecules with molecular weights within 1000–20... more Abstract Poly(1-butene) low molecular weight macromolecules with molecular weights within 1000–20,000 g mol −1 and isotacticities around 50–90% were prepared by the polymerization of 1-butene in liquid phase with n-butane as solvent using two metallocene catalysts: rac-dimethyl-silyl-bis-(2-methyl-4,5-benzoindenyl)zirconium dichloride (A) and rac-dimethyl-silyl-bis-(2-methylindenyl)zirconium dichloride (B). Catalyst A showed higher yields and productivities than catalyst B, as well as better isotacticity values, which were ascribed to the presence of an additional aryl substituent in the indenyl moiety which increases its stability and hinders deactivation phenomena by aggregation. Kinetic experiments with catalyst A showed a continuous increase in conversion along the time so no strong deactivation was observed. With catalyst A, an increase in the hydrogen pressure at 75 °C up to 6.0 bar led towards low molecular weight macromolecules with 3000–4000 g mol −1 and a isotacticity of 75–80%. An enhancement in temperature up to 105 °C decreased the yields, molecular weights and isotacticity for both catalysts. Additionally, increasing the hydrogen partial pressure to 1.0 bar at 95 and 105 °C decreased the molecular weight within the 3000–5500 g mol −1 range. XRD patterns of the majority of low molecular weight macromolecules showed the presence of mixed phases, although some low molecular weight macromolecules with pure phase I (twined hexagonal) were obtained. Additionally, the DSC thermograms showed a decrease in the melting temperatures of the crystalline phases of poly(1-butene) low molecular weight macromolecules with regard to the corresponding ones of poly(1-butene) polymers ( M w > 100,000 g mol −1 ), due to their lower molecular weight.
The present manuscript reports an overview of the design and conceptual approaches to the synthes... more The present manuscript reports an overview of the design and conceptual approaches to the synthesis of rotaxaconjugated polymers (R-CP), such as aromatic polyazomethines, alternating or random polyfluorene copolymers encapsulated inside native CD cavities. Their synthesis correlated with an overview of the photophysical properties, surface morphology and electrochemical behaviours, which are advantageous for the generation of active layers in organic electronic devices, are considered in this review.
Molecules
Herein, we report the synthesis of inclusion complexes (ICs) based on 3,4-ethylenedioxythiophene ... more Herein, we report the synthesis of inclusion complexes (ICs) based on 3,4-ethylenedioxythiophene (EDOT) with permethylated β-cyclodextrins (TMe-βCD) and permethylated γ-cyclodextrins (TMe-γCD) host molecules. To prove the synthesis of such ICs, molecular docking simulation, UV-vis titrations in water, 1H-NMR, and H-H ROESY, as well as matrix-assisted laser desorption ionization mass spectroscopy (MALDI TOF MS) and thermogravimetric analysis (TGA) were carried out on each of the EDOT∙TMe-βCD and EDOT∙TMe-γCD samples. The results of computational investigations reveal the occurrence of hydrophobic interactions, which contribute to the insertion of the EDOT guest inside the macrocyclic cavities and a better binding of the neutral EDOT to TMe-βCD. The H-H ROESY spectra show correlation peaks between H-3 and H-5 of hosts and the protons of the guest EDOT, suggesting that the EDOT molecule is included inside the cavities. The MALDI TOF MS analysis of the EDOT∙TMe-βCD solutions clearly rev...
Beilstein Journal of Organic Chemistry, 2012
The paper reports the preparation of a poly[2,7-(9,9-dioctylfluorene)-alt-5,5'-bithiophene/PS... more The paper reports the preparation of a poly[2,7-(9,9-dioctylfluorene)-alt-5,5'-bithiophene/PS-βCD] (PDOF-BTc) polyrotaxane copolymer, through a Suzuki coupling reaction between the 5,5'-dibromo-2,2'-bithiophene (BT) inclusion complex with persilylated β-cyclodextrin (PS-βCD), and 9,9-dioctylfluorene-2,7-bis(trimethylene borate) (DOF) as the blocking group. The chemical structure and the thermal and morphological properties of the resulting polyrotaxane were investigated by using NMR and FT-IR spectroscopy, TGA, DSC and AFM analysis. The encapsulation of BT inside the PS-βCD cavity results in improvements in the solubility, as well as in different surface morphology and thermal properties of the PDOF-BTc rotaxane copolymer compared to its noncomplexed PDOF-BT homologue. In contrast, the number-average molecular weight (Mn) of PDOF-BTc rotaxane copolymer indicated lower values suggesting that the condensation reaction is subjected to steric effects of the bulkier silylated...
Lubrication aspects, in extreme operating conditions, highlights important problems concerning be... more Lubrication aspects, in extreme operating conditions, highlights important problems concerning bearings design or greases behaviour management for given operating conditions. The researches that were done in the last period were focused on greases service life and behaviour versus rolling bearings operating conditions but, it must be emphasized, that some particular aspects such as the presence of the electrical fields were less studied. Some results in this specific area were previously forwarded by Prashad who highlighted issues such as greases resistivity modifications with time, particular bearings and lubricating greases damaging mechanisms. Aspects concerning temperature influence on grease resistivity, correlations between greases structural, physical and chemical deterioration and bearings specific failures, in the presence of the electrical field, are questions that must be answered. These problems are very important because electrical rotating machines support bearings reliability is strongly dependant on greases service life and performances. The paper presents some correlations between the electrical field characteristics and electrical motors rotors support rolling bearings greases deterioration based on lubricant's SEM and raceways microscopical analyses. Starting from these results it can be concluded that rolling bearings deterioration under the influence of the electrical field is a complex phenomenon with effects, both, on lubricating greases and bearings rolling contact surfaces. From this point, a greases deterioration model, in the presence of the electrical field, will be proposed.
2021 13th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2021
Research activity is packed with a lot of different systems, having different degrees of complexi... more Research activity is packed with a lot of different systems, having different degrees of complexity, interrelated, that have to multitask on multiple leveles, exchange data, collaborate, to achieve the best results in the shortest / optimal time. In order to have a successfully implemented research activity, a system have to be: reliably engineered - that is to function failure free for a given time interval, stable - for a controled interval of values given at input a stable system produces a controled interval of values at output, and not in the end, a quality implementation of the solution [1]. The ultimate goal is to significantly increase the performance, amongst other things by having errors, human and otherwise, less and less present, through the proposed system we constructed where the HPLS will achieve the status of being ”AI and robotically managed”. We integrate, modify, adapt, customize various equipment and make them work best together within our designed architecture - nothing more, nothing less, nothing else. A series of important activities are and can be very time consuming - need to speed up - automate! To release resources towards imagination, creativity, ideas, solutions [1].
Langmuir, 2021
In the present study, we investigated the effect of permodified 2,3,6-tri-O-trimethylsilyl β- and... more In the present study, we investigated the effect of permodified 2,3,6-tri-O-trimethylsilyl β- and γ-cyclodextrin (TMS·β-CD, TMS·γ-CD) encapsulation on the optical, electrochemical, morphological, and supramolecular arrangements of a poly[2,7'-(9,9-dioctylfluorene-alt-2',7-fluorene)] PF copolymer. For this purpose, the photophysical properties and Langmuir monolayer formation of PF·TMS·β-CD and PF·TMS·γ-CD polyrotaxanes were investigated and compared with those of the reference PF. Surface pressure-area isotherms and Brewster angle microscopy studies indicated the capability of both polyrotaxanes to organize into larger and homogeneous 2D supramolecular assemblies at the air-water interface. The obtained results suggest that the presence of the surrounding TMS·β-CD and TMS·γ-CD macrocycles on the PF backbones leads to changes in the conformation and hydrophobicity of the film surfaces. Our investigation offers a method to assess the impact of TMS-CD encapsulation on the control of 2D monolayer formation, with particular attention on the generation of stable PF monolayers for organic electronic devices.
European Polymer Journal, 2017
Cucurbit[7]uril (CB7), native -cyclodextrin (αCD) and its tris-O-methylated derivative (TMαCD) a... more Cucurbit[7]uril (CB7), native -cyclodextrin (αCD) and its tris-O-methylated derivative (TMαCD) as macrocyclic host molecules and amine-terminated poly(ethylene glycol) (PEG) as neutral guest were used for the synthesis of 3-CB7, 3-αCD and 3-TMαCD polyrotaxanes. The binding affinities of the neutral PEG guest into the CB7, CD and TMαCD cavities were evaluated by isothermal titration calorimetry. The high value of the stability constant (1 × 10 4 M −1) indicates that PEG provides a preferential binding to CB7 over CD. The polyrotaxane structure was confirmed by FT-IR and 1 H NMR spectroscopy. The coverage ratio of the PEG with CB7, αCD and TMαCD macrocycles, were 63%, 71%, and 30%, respectively. The polyrotaxanes 3-CB7 and 3-αCD exhibit an enhancement in thermal stability compared with the non-rotaxane 3 counterpart. In addition, polyrotaxane 3-CB7 shows blue-shifted absorption by more than 20 nm and enhanced water solubility.