Browsing by Author "Olea, Andres F."

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Counterion and composition effects on discotic nematic lyotropic liquid crystals - I. Size and order
    (2007) Montecinos Escobar, Rodrigo Andrés; Ahumada, Hernan; Araya Maturana, Ramiro; Olea, Andres F.; Weiss-Lopez, Boris E.
  • No Thumbnail Available
    Item
    Counterion and composition effects on discotic nematic lyotropic liquid crystals - II. Ion exchange and molecular dynamics
    (2007) Montecinos Escobar, Rodrigo Andrés; Ahumada, Hernan; Bahamonde-Padilla, Victor E.; Olea, Andres F.; Weiss-Lopez, Boris E.
  • No Thumbnail Available
    Item
    Influence of Hydrogen Bond Acceptors and Water Content on Surface Tension in Glycol-Based Eutectic Mixtures
    (2024) Aravena, Paulo; Cea-Klapp, Esteban; Gajardo-Parra, Nicolas F.; Olea, Andres F.; Carrasco, Hector; Matias Garrido, Jose; Canales, Roberto I.
    One of the environmental concerns in the chemical industry is using organic solvents that are not environmentally friendly. Eutectic mixtures, also called deep eutectic solvents (DESs), have emerged as their substitutes due to favorable properties, including biodegradability, tunability, and low cost, among others. DESs show applications in extractions, biocatalysis, etc. To expand their uses, it is crucial to characterize their properties and understand their interactions with other solvents. In this study, the surface tension of DESs between 30 and 60 degrees C at 101.3 kPa was measured. The DESs were prepared using choline chloride or betaine as the hydrogen bond acceptor (HBA) and a glycol (ethylene glycol, 1,2-propanediol, 1,3-propanediol, or 1,4-butanediol) as the hydrogen bond donor (HBD) in different molar ratios. The surface tension of DESs + water mixtures was measured over the entire range of compositions. To assess the effect of temperature, HBD chain length, and water content, PC-SAFT coupled with the density gradient theory was used to model the surface tension. Furthermore, molecular dynamics simulations were conducted to gain a molecular understanding of the components at the interface. The molecular insights obtained from these simulations and the experimental data can help reduce the number of experiments when designing DESs for chemical processes.
  • Thumbnail Image
    Item
    Solubilization of Phenol Derivatives in Polymer Micelles Formed by Cationic Block Copolymer
    (HINDAWI LTD, 2017) Fuentes, Irma; Silva, Patricio; Martinez, Francisco; Olea, Andres F.
    The aggregation of cationic block copolymers formed by polystyrene (PS) and poly(ethyl-4-vinylpyridine) (PS-b-PE4VP) was studied in aqueous solution. Diblock copolymers of PS and poly(4-vinylpyridine) were synthesized by sequential anionic polymerization using BuLi as initiator. Subsequently, the 4-vinylpyridine units were quaternized with ethyl bromide to obtain cationic PS-b-PE4VP block copolymers with different quaternization degree. The self-aggregation of cationic block copolymers was studied by fluorescence probing, whereas the morphology and size of polymer micelles were determined by transmission electronic microscopy. Results indicate that spherical micelles with sizes lower than 100 nm were formed, whereas their micropolarity decreases with increasing quaternization degree. The partition of phenols between the micellar and aqueous phase was studied by using the pseudo-phase model, and the results show that the partition coefficients increase with increasing length of the side alkyl chain and are larger for star micelles. These results are discussed in terms of three-region model.