Home Seminarios
Seminarios

Seminari IQAC

Rejuvenation of old-dated formulation tools:  Using the Phase inversion temperature to classify surfactants and study the oil segregation in mixtures.


Dr. Jesus F. Ontiveros

ENSCL, Univ. Lille, CNRS, UMR 8181, Unité de Catalyse et Chimie du Solide

July 25th 11.00h at Room B

Sixty-eight years after the introduction of the empirical HLB concept by Griffin1, this value is still the most commonly used scale to characterize surfactants. For the formulation of Surfactant/Oil/Water systems, the hydrophobicity of the oily phase is quantified by the “required HLB”. Newer and more scientifically founded concepts such as the « critical packing parameter »2, and the «Hydrophilic Lipophilic Deviation»3, did not lead to a general classification of surfactants. The semi-empirical parameters appearing in the HLD equations reflect the Hydrophilic–Lipophilic Balance of surfactants and the hydrophobicity of oils. However, the complexity of the systems and the long time needed to obtain phase equilibrium discourage experimenters.
The modification of the phase inversion temperature4 (PIT) of C10E4/n-octane/water emulsions was studied as a function of increasing amounts of additional second surfactant. The PIT of the “perturbed” reference system exhibits a quasi-linear variation versus the mole fraction of the second surfactant added in the mixture. This variation was used to classify them according to their hydrophilic lipophilic balance respect to the C10E45. New biosourced surfactants can be compared respect to other well-known surfactants with a simple approach. Using this method, the oil that allows obtain a three phase behavior at 25°C without alcohol or salt for non-ionic surfactants is estimated with an acceptable accuracy.
Finally, the PIT of several C10E4/Oil/water emulsions is also used as a tool to quantify the “hydrophobicity” of the oils (the EACN parameter in HLD equation) and also to evaluate the most important factors that contribute to the segregation of oils at the interface.

 

Seminari IQAC

Synthetic Tubular Molecules Mimicking the Function of Channel Proteins


Jun-Li Hou

Department of Chemistry, Fudan University

July 19th  12:00 h

 In natural systems, channel proteins are responsible for the processing of ion and molecular inputs and exports, sensing environmental stimuli and signals across cell membranes. Because of the important function of channel proteins, chemists proposed to construct artificial systems to mimick the function of the channel proteins, which might help us on understanding the transport mechanisms, creating materials for separation, and developing therapeutic agents.We are interested in the construction of confined unimolecular tubular channels by considering their predictable conformation, high capacity of inserting into lipid bilayers. By using the rigid and symmetric pillar structure of pillararene, we have constructed a series of synthetic tubular molecules which have displayed unique properties for selective transmembrane transport of proton, water, amino acids, and voltage-gated and uphill transport of K+. By further precise modification of the channel structure, we have also achieved the selective recognition of the bilayer membrane of Gram-positive bacteria, which led to the high antimicrobial activity.

 

Seminari IQAC

Nanoparticles as contrast agents with a focus on 19F-MRI


Mónica Carril

CIC BiomaGUNE, San Sebastián, Spain

14th July 12.00h

In the last decades, nanotechnology has widely contributed to the field of preclinical contrast-enhanced imaging, and nowadays nanoparticles (NPs) as imaging probes are ubiquitous in MRI studies, among other imaging technologies. Fluorine 19 (19F) based MRI is a re-emerging field with promising features which complement proton-based traditional MRI. The most interesting advantage of 19F over 1H is the negligible endogenous 19F-MRI signal, for which any detectable signal can only come from an exogenous probe. However, in order to achieve a quality of image similar to that obtained with conventional MRI, a high load of fluorine atoms with the same resonance frequency is required. One of the main challenges in this field at the moment is the improvement of existing contrast agents in order to increase the SNR and circumvent the intrinsic hydrophobicity of fluorinated probes. Taking this into account, the use of NPs bearing a high number of identical fluorinated ligands could be an appealing strategy to increase the local concentration of chemically equivalent fluorine atoms. In this context, novel fluorine labels for nanoparticles have been designed, synthesised, characterised and tested as potential imaging probes.

 

Seminari IQAC

Synthesis of nanoparticles and nanocomposites by nanoemulsion and semicontinuous heterophase polymerization processes


Jorge E. Puig
Departamento de Ingeniería Química, UNIVERSIDAD DE GUADALAJARA, GUADALAJARA, MÉXICO


13 de  juny a la Sala d'Actes a les 11 hores

 

Seminari de l'IQAC

Theoretical study of heterogeneous photocatalysis:

Water oxidation on TiO2 under ultra-high vacuum conditions

Annapaola Migani


Institute of Advanced Chemistry of Catalonia (IQAC), CSIC
Department of Biological Chemistry and Molecular Modelling
Theoretical and Computational Chemistry Group
 

Dijous, 1 de Juny de 2017, a les 12:00 h. Saló d’Actes del CID

 


Página 4 de 5