The Experts below are selected from a list of 28728 Experts worldwide ranked by ideXlab platform

Alberto Alvarezfernandez - One of the best experts on this subject based on the ideXlab platform.

  • tailoring block copolymer nanoporous thin films with acetic acid as a small Guest Molecule
    Polymer International, 2019
    Co-Authors: Alberto Alvarezfernandez, Fernando Valdesvango, J I Martin, M Velez, C Quiros, Daniel Hermidamerino, Giuseppe Portale, J M Alameda, Francisco Garcia J Alonso
    Abstract:

    Block copolymers offer the fabrication of mesoporous thin films with distinct nanoscale structural features. In this contribution, we present the use of acetic acid (CH3COOH) as a low-molecular-weight Guest Molecule to tune the supramolecular assembly of poly[styrene-block-(4-vinylpyridine)] (PS-b-P4VP), offering a versatile and straightforward method to obtain tailored nanostructured films with controlled topography and pore size. Spin-coating toluene solutions of PS-b-P4VP, with a variable amount of CH3COOH, leads to micellar thin films, where the micelles contain the carboxylic acid as a Guest Molecule. The size can be conveniently modified in these films (from 48 to 75 nm) by varying the amount of organic acid in the starting solutions. Subsequent surface reconstruction of micellar films using ethanol leads to ring-shaped copolymer nanoporous films with modulated diameter. Controlling the micelle reconstruction process, cylindrical porous films are also obtained. Interestingly, changing the type of aliphatic carboxylic acid leads to a modification of the observed film morphology from micelles to out-of-plane P4VP cylinders (or lamellae) in a PS matrix. (c) 2019 Society of Chemical Industry

A I Konovalov - One of the best experts on this subject based on the ideXlab platform.

S Thayumanavan - One of the best experts on this subject based on the ideXlab platform.

  • multi stimuli sensitive amphiphilic block copolymer assemblies
    Journal of the American Chemical Society, 2009
    Co-Authors: Akamol Klaikherd, Chikkannagari Nagamani, S Thayumanavan
    Abstract:

    Stimuli-responsive polymers are arguably the most widely considered systems for a variety of applications in biomedical arena. We report here a novel triple stimuli sensitive block copolymer assembly that responds to changes in temperature, pH and redox potential. Our block copolymer design constitutes an acid-sensitive THP-protected HEMA as the hydrophobic part and a temperature-sensitive PNIPAM as the hydrophilic part with an intervening disulfide bond. The micellar properties and the release kinetics of the encapsulated Guest Molecule in response to one stimulus as well as combinations of stimuli have been evaluated. Responsiveness to combination of stimuli not only allows for fine-tuning the Guest Molecule release kinetics, but also provides the possibility of achieving location-specific delivery.

  • effect of Guest Molecule flexibility in access to dendritic interiors
    Organic Letters, 2005
    Co-Authors: Sivakumar V Aathimanikandan, Britto S Sandanaraj, Christopher G Arges, Christopher J Bardeen, S Thayumanavan
    Abstract:

    Dendrimers are attractive scaffolds for catalysis, since catalytic sites can be isolated and the catalysts are recoverable and reusable. Herein, we show that conformationally constrained Molecules have better access to dendritic cores compared to the more flexible counterparts. The results reported here should have implications in utilizing dendrimers as scaffolds for artificial selectivity in catalysis.

Francisco Garcia J Alonso - One of the best experts on this subject based on the ideXlab platform.

  • tailoring block copolymer nanoporous thin films with acetic acid as a small Guest Molecule
    Polymer International, 2019
    Co-Authors: Alberto Alvarezfernandez, Fernando Valdesvango, J I Martin, M Velez, C Quiros, Daniel Hermidamerino, Giuseppe Portale, J M Alameda, Francisco Garcia J Alonso
    Abstract:

    Block copolymers offer the fabrication of mesoporous thin films with distinct nanoscale structural features. In this contribution, we present the use of acetic acid (CH3COOH) as a low-molecular-weight Guest Molecule to tune the supramolecular assembly of poly[styrene-block-(4-vinylpyridine)] (PS-b-P4VP), offering a versatile and straightforward method to obtain tailored nanostructured films with controlled topography and pore size. Spin-coating toluene solutions of PS-b-P4VP, with a variable amount of CH3COOH, leads to micellar thin films, where the micelles contain the carboxylic acid as a Guest Molecule. The size can be conveniently modified in these films (from 48 to 75 nm) by varying the amount of organic acid in the starting solutions. Subsequent surface reconstruction of micellar films using ethanol leads to ring-shaped copolymer nanoporous films with modulated diameter. Controlling the micelle reconstruction process, cylindrical porous films are also obtained. Interestingly, changing the type of aliphatic carboxylic acid leads to a modification of the observed film morphology from micelles to out-of-plane P4VP cylinders (or lamellae) in a PS matrix. (c) 2019 Society of Chemical Industry

Yuji Kikukawa - One of the best experts on this subject based on the ideXlab platform.

  • solid state umbrella type inversion of a vo5 square pyramidal unit in a bowl type dodecavanadate induced by insertion and elimination of a Guest Molecule
    Angewandte Chemie, 2018
    Co-Authors: Yuji Kikukawa, Kensuke Seto, Sayaka Uchida, Sho Kuwajima, Yoshihito Hayashi
    Abstract:

    : Design of cavities for a target Molecule and the elucidation of the corresponding host-Guest interactions are important for molecular manipulation. A discrete dodecavanadate bowl, [V12 O32 ]4- (V12), with an entrance diameter of 4.4 A and an electron-rich Guest at the center of the bowl, was stabilized by electrostatic interactions. A characteristic of V12 is a solid-state polytopal rearrangement during Guest elimination and recapture. A Guest-free dodecavanadate, [V12 O32 ]4- (V12-free), was prepared by removal of the Guest from CH2 Cl2 -inserted V12 under vacuum at 50 °C. Single-crystal X-ray analysis revealed that one of the VO5 square pyramids at the bottom of V12-free was inverted to fill the void of the bowl cavity. The exposure of V12-free to the Guest Molecule vapors of CH2 Cl2 , 1,2-dichloroethane, MeNO2 , MeCN, and MeBr resulted in the selective insertion of the Guest to reform the Guest-inserted V12 structure. Whereas CO2 could be inserted in the V12 bowl, CH4 and CO could not.

  • solid state umbrella type inversion of a vo 5 square pyramidal unit in a bowl type dodecavanadate induced by insertion and elimination of a Guest Molecule
    Angewandte Chemie, 2018
    Co-Authors: Yuji Kikukawa, Kensuke Seto, Sayaka Uchida, Sho Kuwajima, Yoshihito Hayashi
    Abstract:

    Design of cavities for a target Molecule and the elucidation of the corresponding host-Guest interactions are important for molecular manipulation. A discrete dodecavanadate bowl, [V12 O32 ]4- (V12), with an entrance diameter of 4.4 A and an electron-rich Guest at the center of the bowl, was stabilized by electrostatic interactions. A characteristic of V12 is a solid-state polytopal rearrangement during Guest elimination and recapture. A Guest-free dodecavanadate, [V12 O32 ]4- (V12-free), was prepared by removal of the Guest from CH2 Cl2 -inserted V12 under vacuum at 50 °C. Single-crystal X-ray analysis revealed that one of the VO5 square pyramids at the bottom of V12-free was inverted to fill the void of the bowl cavity. The exposure of V12-free to the Guest Molecule vapors of CH2 Cl2 , 1,2-dichloroethane, MeNO2 , MeCN, and MeBr resulted in the selective insertion of the Guest to reform the Guest-inserted V12 structure. Whereas CO2 could be inserted in the V12 bowl, CH4 and CO could not.