jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Christian Bellacanzone
Source: LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (article, 2018-01-01)
Field: Materials Science — Polymers and Plastics

Tuning of the poly(p-phenylenevinylene) derivatives emission properties by phase change materials and sonochemistry Los polímeros conjugado (CP) son un material muy interesante con propiedades optoelectrónicas peculiares que hacen de estos polímeros óptimos candidatos por distintas aplicaciones cuáles OLEDs y celdas organicas fotovoltaicas y también por bioimagen y liberación de fármacos. En los últimos años creciente atención se ha dirigido hacía la modulación de las prioridades ópticas de los CP para poderlos emplear en distintos ámbitos. El objetivo de este trabajo es de lograr un ajuste fino de la emisión de los derivados de polifenileno vinileno (PPV) . Dos estrategias principales se han adoptados. I) Nanoparticulas de oligomeros de PPV con distintas longitudes de conjugación se han producido mediante síntesis sonoquímica. La irradiación con ultrasonidos ha sido aplicada a una solución heterogénea de polímero PPV para inducir la activación de especies radicales que rompen los enlaces doble del polímero cortándolo y generando oligomeros de PPV. La copresencia de un tensioactivo dirige la simultánea nanostructuración de los oligomeros generando nanoparticulas soluble en agua que presentan un progresivo cambio hipsocrómico de las bandas espectrales en absorción y emisión comparado con el polímero inicial. Tal nanoparticulas pueden ser utilizadas en OLEDs y bioimagen. II) los oligomeros y el polímero de PPV fueron mezclados con materiales a cambio de fase de distinto punto de fusión. Cuando tal sistema mixto es calentado, se induce la transición de solido a liquido en el PCM provocando un cambio de fluorescencia hacía el azul. Una vez que el sistema se enfríe y solidifica la emisión inicial es recuperada. Semejante sistema se puede utilizar por la fabricación de sensores de temperatura florecientes y multicolores. También podrías destinar a la realización de diodos orgánico de luz blanca termoregulados aprovechando de la emisión roja, verde y blue de los oligomeros obtenidos en este trabajo Humanities ; Physics ; Chemistry ; Philosophy ; Materials science Conducting polymers and applications ; Organic Electronics and Photovoltaics ; Organic Light-Emitting Diodes Research
Authors: Wan Xu
Source:  (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Iron-modified mesoporous silica as efficient heterogeneous lewis acid catalysts Les catalyseurs hétérogènes acides de Lewis ont principalement attiré beaucoup d'attention à cause de leurs applications dans de nombreux processus chimiques tels que le raffinage de pétrole. De plus, la facilité de séparer avec la phase liquide, et peu de déchets dangereux générés dans les processus répondent aux exigences de la chimie verte. Par conséquent, il est nécessaire de concevoir les catalyseurs acides de Lewis de façon simple, efficace, et peu couteux. Pour ce faire, la silice mésoporeuse peut agir comme support potentiel pour ce type de catalyseurs hétérogènes. La silice mésoporeuse possède les propriétés physiques et chimiques adaptées tel que la surface spécifique élevés, le volume de pore grand, la taille des pores accordable et ajustable, et la facilité de fonctionnalisation de la surface. Par conséquent, l'objectif de cette thèse est d'explorer un procédé de synthèse facile pour préparer 'un catalyseur d'acide de Lewis hétérogène efficace en utilisant la silice mésoporeuse ordonnée fonctionnalisé par des métaux peu couteux. Pour cela, les silices mésoporeuses du type MCM-41, et SBA-15 ont été choisis comme supports de catalyseur. Par la suite, Fe- MCM-41 et Fe-SBA-15 ont été correctement synthétisé en utilisant un procédé polyvalent. Le traitement de l'ammoniac au cours de la synthèse a été trouvé être un moyen efficace d'augmenter la teneur en fer tout en préservant la dispersion convenable des cations métalliques. Les paramètres physicochimiques de la silice mésoporeuse finale contenant du fer ont été obtenus par l’analyse d'adsorption-désorption d'azote à la base température, et l'environnement de la coordination des éléments en fer a été validé par la spectroscopie de UV-Vis réflectance diffusée et la spectroscopie photoélectronique à rayons X. L'acidité de surface a été sondé à l'aide des indicateurs de Hammett. Pour distinguer en outre les sites acides de Lewis sur la surface, l’adsorption de pyridine suivie par FTIR a été mise en oeuvre. Ces catalyseurs préparés ont été criblés dans la réaction d'aldolisation de Mukaiyama, qui est une réaction modèle catalysée par l’acide de Lewis. L'activité catalytique acide de Lewis des matériaux était peaufinées et les produits aldol ont été obtenus avec un bon rendement et la sélectivité. De plus, les catalyseurs hétérogènes sont très stables et peuvent être réutilisés au moins neuf fois en conservant l’activité catalytique. Catalysis ; Mesoporous material ; Lewis acids and bases ; Mesoporous silica ; Chemistry ; Organic chemistry Mesoporous Materials and Catalysis ; Chemical Synthesis and Reactions
Authors: Terence Blaskovits
Source:  (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

Une étude computationnelle de la polymérisation par (hétéro)arylation directe : [A Computational Study of Direct (Hetero)arylation Polymerization] En comparaison avec d’autres techniques de couplage-croisé adaptées à la synthèse de polymères conjugués, la polymérisation par (hétéro)arylation directe (PHAD) s’avère avantageuse d’une perspective industrielle et environnementale. En effet, elle permet d’éviter l’utilisation d’agents de transmétallation nécessaires aux méthodes classiques de polymérisation. La réaction de PHAD exploite l’activation de liens aromatiques carbone-hydrogène (C–H) pour une synthèse efficace de polymères conjugués avec une excellente économie d’atomes. La réaction d’(hétéro)arylation directe permet la formation d’un lien entre deux atomes de carbone d’hybridation sp2 à partir d’un lien C–H via l’état de transition de la métallation-déprotonation concertée (CMD). La majorité des polymères conjugués utilisés en électronique organique contient des unités de répétition à base de thiophène. Cet hétérocycle, possédant des propriétés électroniques et stériques désirables, sont fonctionnalisés avec des groupes donneurs ou accepteurs d’électrons, ainsi qu’avec des chaînes aliphatiques à des fins de solubilité. Cependant, l’utilisation du motif thiophène peut mener à des défauts structuraux dans la chaîne polymère puisqu’elle comporte plusieurs liens C–H activables en PHAD. Si un lien C-H non-désiré (en position β du motif thiophène) est activé plutôt que le lien en position α, un défaut en β peut alors être incorporé de manière covalente dans la structure polymérique résultante. La présence de défauts en β mène à une perturbation de la conjugaison du polymère et de l’organisation du matériau à l’état solide, des facteurs qui peuvent réduire les performances en dispositifs d’électronique organique. Étant donné l’omniprésence du motif thiophène au sein des polymères conjugués et sa sélectivité parfois problématique, une étude computationnelle du mécanisme de l’arylation directe sur des unités thiophènes modèles a été entreprise dans le cadre de ce projet. En utilisant la théorie de la fonctionnelle de la densité et le cluster couplé, les barrières d’activation pour l’état de transition de la CMD de plusieurs substrats modèles ont été calculées et analysées par la méthode de la distorsion-interaction. L’effet activant d’un halogène sur les liens C–H adjacents à celui-ci a été étudié. Les résultats permettront de guider la conception de monomères pour la réalisation de matériaux régioréguliers par PHAD. Chemistry ; Polymer chemistry Catalytic Cross-Coupling Reactions ; Advanced Polymer Synthesis and Characterization ; biodegradable polymer synthesis and properties
Authors: Sean Daly
Source: The Sydney eScholarship Repository (The University of Sydney) (article, 2018-08-30)
Field: Materials Science — Biomaterials

Purification and Modification of Poly (β-hydroxybutyrate) for Food Packaging and Biomedicine Applications Due to growing concern over the environmental impact of the global polymer industry, there is increasing interest in sustainable alternatives. Poly (β-hydroxybutyrate) (PHB) is posed as a viable renewable and biodegradable alternative to conventional polyolefins, particularly for food packaging and biomedical applications. However, PHB has limitations in that it is extremely brittle, hydrophobic and contains trace amounts of undesirable embedded impurities. Addressing these limitations is necessary to enable the commercial application of PHB and is the focus of this thesis. High pressure CO2 technologies, can effectively remove up to 93 ± 3 wt% of these embedded residues, this purification process makes PHB suitable for use in food packaging and for biomedicine. A novel tri-blend of PHB with Polypropylene Carbonate (PPC) and a PHB-based modifier can achieve comparable tensile strength (up to 17 MPa), rigidity (up to 320 MPa) and elasticity (up to 240%) to conventional polyolefins currently used for food packaging. The performance of the novel blend was further evaluated by the fabrication of effective orthopaedic screws. Similarly, the inclusion of a PHB-based crosslinking agent in a conventional hydrogel provided 4-17 fold superior strength per strain performance over the other commercially available cross-linkers examined, such as poly (ethylene glycol) diacrylate (PEGDA) and methacryl-polyhedral oligomeric silsesquioxane. These PHB-based hydrogels were found also to have superior rigidity (0.95-18 MPa) and comparable strength (580-1750 kPa) to some toughened hydrogel systems. The simplified fabrication method of these PHB hydrogels can be easily utilised in advanced processing technologies, such as 3D printing. The three technically feasible solutions proposed in this dissertation overcome the limitations to the further utilisation of PHB within the food packaging and biomedical markets leading PHB to become the biopolymer of the 21st century. Food packaging ; Biomedicine ; Food science ; Process engineering ; Biochemical engineering ; Nanotechnology ; Chemistry ; Materials science ; Engineering ; Biology biodegradable polymer synthesis and properties ; Microplastics and Plastic Pollution ; Additive Manufacturing and 3D Printing Technologies
Authors: Mohammed Dyia Hussien | Luminița Măruțescu | Mariana Carmen Chifiriuc
Source: Reviews in Biological and Biomedical Sciences (article, 2018-07-09)
Field: Materials Science — Materials Chemistry

Nanotechnological approaches for the development of novel antimicrobial strategies Due to their diverse and multiple antimicrobial features, inorganic and organic nanoparticles (NPs) represent promising candidates for the development of novel antimicrobial strategies, which could be used to complement current antimicrobial agents that fail to combat pathogens, including multidrug-resistant and biofilmforming microorganisms. The high surface / volume ratio of NPs provides a maximum loading of therapeutic molecules. Additionally, NPs coated with different antimicrobial agents could represent an important alternative strategy to combat biofilm infections. Among the most common types of NPs, the metal, metal oxide and carbonbased NPs are the most used for antimicrobial applications and the purpose of this review is to present some of their antimicrobial features. Antimicrobial ; Nanotechnology ; Biofilm ; Microbiology ; Materials science ; Biology ; Bacteria Nanoparticles: synthesis and applications ; Antimicrobial agents and applications ; Graphene and Nanomaterials Applications
Authors: Hui‐Chun Lee
Source: Max Planck Digital Library (article, 2018-01-01)
Field: Chemistry — Inorganic Chemistry

Toward Ultimate Control of Polymerization and Catalytic Property: A Combination of Metal-Organic Frameworks and ATRP It reminisces me the day I left home, a sunny day in Taiwan.My feeling was extremely complicated, afraid, nervous and exciting, because I had prepared for this moment for a long time and was going to explore this world, but this time without my beloved family.Always, time flies faster than our imagination.It has been more than two years since I am here in Polymerization ; Catalysis ; Property (philosophy) ; Metal-organic framework ; Polymer chemistry ; Materials science ; Chemistry ; Polymer ; Organic chemistry ; Adsorption Metal-Organic Frameworks: Synthesis and Applications ; Chemical Synthesis and Reactions ; Catalytic Processes in Materials Science
Authors: Dinesh Jagadeesan | Dnyanesh Vernekar | Sharad Gupta | Garima Jaiswal
Source: Revista de Fomento Social (article, 2018-10-01)
Field: Materials Science — Materials Chemistry

New Opportunities in Heterogeneous Catalysis Nearly 80% of the processes involved in the chemical production of bulk or fine chemicals employ heterogeneous catalysts that are typically solids. The heart of the heterogeneous catalyst is the surface active site which must be highly active, selective and stable during several hundred cycles of reaction. Although it is not always possible to determine the structure of an active site in a heterogeneous catalyst, the emphasis of modern day research has not only been to understand the structure of an active site but also synthesize and study them. The article will describe some of the challenges from this perspective with examples from the authors research. Nanotechnology ; Materials science Catalytic Processes in Materials Science ; Asymmetric Hydrogenation and Catalysis ; Catalysis and Oxidation Reactions
Authors: Serpil Denizaltı
Source: Celal Bayar Üniversitesi Fen Bilimleri Dergisi (article, 2018-03-26)
Field: Chemistry — Inorganic Chemistry

Transfer Hydrogenation of Ketones Using Pyridine-Aminoalcohol Ligands Pyridine-aminoalcohol ligands were synthesized and evaluated as catalyst generated in situ from RuCl2(PPh3)3 for transfer hydrogenation of aromatic ketones. It was found that the ligand I was more active than II. Pyridine ; Transfer hydrogenation ; Catalysis ; Chemistry ; Ligand (biochemistry) ; Noyori asymmetric hydrogenation ; Combinatorial chemistry ; Organic chemistry ; Medicinal chemistry ; Ruthenium ; Receptor ; Biochemistry Asymmetric Hydrogenation and Catalysis ; Catalysis for Biomass Conversion ; Nanomaterials for catalytic reactions
Authors: Xiaoyan Lu
Source: Journal of International Crisis and Risk Communication Research (article, 2018-01-01)
Field: Materials Science — Polymers and Plastics

Polyelectrolyte Complexes Based on Poly(acrylic acid): Mechanics and Applications Poly(acrylic acid) (PAA) is a weak polyelectrolyte presenting negative charge at basic condition when the carboxylic group loses a proton. These carboxylate group can interact with polycations and metal ions to form stable polyelectrolyte complexes (PECs), leading to tunable properties and multifunctional nanoscale structures through chemical reactions. This research focuses on nanofiber and nanoparticle fabricated by PAA-based PECs. We demonstrated the effect of ferric ion concentration on the mechanical properties of PAA-based single naonofiber by using dark field microscopy imaging and persistence length analysis. The application of PAA-based nanofiber mats loaded with MnO2 for supercapacitors was also explored. As a free-standing and flexible supercapacitor electrode, the nanofiber mat exhibited outstanding properties including high specific capacitance, excellent reversible redox reactions, and fast charge/discharge ability. Since PAA is a biocompatible polymer, PAA-based PEC was applied as a drug-carrier in a drug delivery system. In this project, core-shell nanoparticles were fabricated with chitosan as the core and PAA as the shell to incorporate with the drug gemcitabine. Several parameters were investigated to obtain the optimal nanoparticle size. The as-prepared drug delivery system shows prolonged releasing profile. Polyelectrolyte ; Acrylic acid ; Polymer science ; Materials science ; Polymer chemistry ; Polymer ; Composite material ; Copolymer Synthesis and properties of polymers ; Dendrimers and Hyperbranched Polymers ; Advanced Polymer Synthesis and Characterization
Authors: Jui‐Hung Hsu
Source: OakTrust (Texas A&M University Libraries) (article, 2018-04-30)
Field: Materials Science — Materials Chemistry

Electronic and Thermoelectric Properties at the Interface of Organic Thermoelectric Materials Composites made of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and carbon nanotube (CNT) have shown unchanged or even increased thermopower when electrical conductivity was raised by altering the concentration of CNT and/or treating the composites with a polar solvent, dimethyl sulfoxide (DMSO) or an acid, formic acid (FA). In this study, an intermediate CNT concentration showed the highest thermopower and power factor unlike other typical reports with organic composites. The origin of the unusual transport properties was suggested by studying changes in the relative ratio of conducting PEDOT core and insulating PSS, morphology, and carrier concentration and mobility. Our results indicate that the PSS removal by DMSO and FA could alter the carrier transport barrier, and CNT-PEDOT junctions could increase thermopower for composites with a low CNT concentration by avoiding direct contacts between CNTs. For further studying the role of energy barrier at the junctions, organic electrochemical transistor (OECT) was employed as a vehicle to modulate relative energy levels of PEDOT and CNT. By constructing the band diagram at the junction with HOMO, LUMO, and Fermi levels determined by CV, KPFM, and UPS with and without applying gate voltage, the correlation between electrical and thermoelectric properties and the energy barrier height was established. An optimized power factor of 1047 μW/m-K^2 was obtained with a 15 V gate voltage and 0.27 eV energy barrier. The improvement of power factor was attributed to the enhancement of thermopower due to energy filtering effect with minimally affected electrical conductivity. Further, devices with 1 through 8 CNT-PEDOT junctions were fabricated with barrier height fine-tuned through hydrazine reduction to the optimized condition (0.27 eV). A promising power factor of up to 1299 μW/m-K^2 was obtained with a device with 6 junctions. Thermoelectric effect ; Thermoelectric materials ; Materials science ; Interface (matter) ; Electronic materials ; Engineering physics ; Thermoelectric cooling ; Nanotechnology ; Composite material ; Thermodynamics ; Physics Advanced Thermoelectric Materials and Devices
Authors: Assunta De Nisi
Source: AMS Dottorato Institutional Doctoral Theses Repository (University of Bologna) (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

Novel insights into gold(I) chemistry: from anticancer activity to new synthetic methodologies. The work herein presented, embraces various aspects of gold chemistry: the documentation of novel [alkynyl(triphenylphosphine)gold(I)] complexes carrying differently substituted propargylic amines and their pharmacological investigation on a series of cancer cell lines and the investigation of the dearomative cycloaddition reaction of indoles with electron-rich allenes catalysed by commercially available gold(I) complexes that show competence in performing the chemo-, regio- and diastereoselective formal [2+2]-cycloaddition between a wide range of substrates under mild conditions. It has also been developed the combined efficiency of Bu4N+ and F− ions in performing a cascade sequence involving intramolecular hydroamination of the C–C triple bond, cleavage of silyl-protecting groups and site-selective sigmatropic aza-Cope-type [3,3]-rearrangement. Cycloaddition ; Chemistry ; Hydroamination ; Intramolecular force ; Combinatorial chemistry ; Cleavage (geology) ; Stereochemistry ; Organic chemistry ; Catalysis ; Materials science Catalytic Alkyne Reactions
Authors: Parasmani Pageni
Source: Scholar Commons (University of South Carolina) (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

Cationic Metallocene-Containing Biomaterials For Antimicrobial Applications Metal-containing polymers or metallopolymers, are one of the major classes of polymers which stand out independently because of a unique combination of organic and inorganic components in one macromolecular system. Among the variety of metallopolymers, metallocene-containing polymers have been widely utilized for applications ranging from electrochemical sensors to templates for advanced inorganic catalysts to battery materials, due to their unique physicochemical properties. This dissertation is focused on the synthesis, characterization, and application of cationic metallocene-containing polymeric materials. Cationic-cobaltocenium was grafted in various inorganic nanoparticles using polymerization techniques such as reversible addition-fragmentation chain transfer polymerization. In Chapter 1, the overall background of metallopolymers, antimicrobial polymers and modification of nanoparticle polymerization methods is included. Chapter 2 focuses on the study of electrostatic charge on the relative affinity and comparison of the relative binding strength of a cobaltocenium-containing polyelectrolyte. The nature and relative strength of intermolecular interaction between cationic polyelectrolytes and anionic probes were investigated. Chapter 3-4 reports the preparation of inorganic silica and iron oxide nanoparticles grafted with charged cobaltocenium-containing metallopolymers by surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization. In Chapter 5, cobaltocenium-containing polymers were coated on gold nanoparticles by a grafting-to mechanism. β-lactam antibiotic like penicillin-G were then conjugated with all the nanoparticles by ion-pairing between the cationic cobaltocenium moiety in the nanoparticles and carboxylate anions of antibiotics. Such bio-conjugated nanoparticles not only reduced the activity of β-lactamase but effectively lysed both Gram-positive and Gram-negative bacterial cells. All these nanoparticles were characterized and subjected for antimicrobial evaluation against a range of bacteria and biocompatibility with mammalian cells. Cationic polymerization ; Antimicrobial ; Metallocene ; Polymer science ; Materials science ; Chemistry ; Polymer chemistry ; Polymer ; Organic chemistry ; Polymerization Advanced Polymer Synthesis and Characterization ; Antimicrobial agents and applications ; Dendrimers and Hyperbranched Polymers