• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Order in Thin Films of Diblock Copolymers by Supramolecular Assembly / Ordnung in Dünnen Filmen von Diblock-Copolymeren durch Supramolekulare Strukturierung

Tokarev, Ihor 07 November 2004 (has links) (PDF)
Thin membranes with dense periodic arrays of nanoscopic voids were fabricated using the principles of supramolecular assembly and self-organization in polymers. Such nanoporous membranes can be used as templates for synthesis and patterning of various organic and inorganic materials. In this thesis 4-vinylpyridine fragments of polystyrene-block-poly(4-vinylpyridine) (PS-PVP) were associated with the molecules of two different low molar mass additives, 2-(4'-hydroxybenzeneazo)benzoic acid (HABA) and 3-n-pentadecyl phenol (PDP), via hydrogen bonds. The choice of an additive and a solvent is a key factor which influences the morphologies of the PS-PVP+HABA associates (supramolecular assemblies) in thin films. The reversible association via hydrogen bonds allows the amphiphilic molecules of PDP to phase segregate on the free air interface. Unlike, the molecules of HABA remain associated within cylindrical and lamellar domains formed by the PVP block. A solvent used for film deposition influences the orientation of PVP+HABA domains with respect to the confining interfaces. The films deposited from 1,4-dioxane – a good solvent for PS and a bad one for PVP+HABA – demonstrated the perpendicular orientation of PVP+HABA domains. Meanwhile, the preparation of films from a chloroform solution – a good solvent for both PS and PVP+HABA – led to the parallel alignment. The orientation was independent on the film thickness (within the studied range of 20–100 nm) and insensitive to the chemical nature of a substrate. The orientation of the domains was shown to switch upon exposure to vapors of the above mentioned solvents from the parallel to perpendicular orientation and vice versa. Moreover, the swelling of the films in solvent vapors resulted in the significant improvement of the domain ordering. Extraction of HABA with selective solvent transformed of PVP+HABA domains into channels with reactive PVP chains on the walls. The resulted membranes with the perpendicular oriented channels (the diameter about 8 nm, the inter-channel distance 24 nm) were used as a template for the creation of ordered arrays of nanodots from nickel, chromium and gold.
2

Order in Thin Films of Diblock Copolymers by Supramolecular Assembly

Tokarev, Ihor 25 June 2004 (has links)
Thin membranes with dense periodic arrays of nanoscopic voids were fabricated using the principles of supramolecular assembly and self-organization in polymers. Such nanoporous membranes can be used as templates for synthesis and patterning of various organic and inorganic materials. In this thesis 4-vinylpyridine fragments of polystyrene-block-poly(4-vinylpyridine) (PS-PVP) were associated with the molecules of two different low molar mass additives, 2-(4'-hydroxybenzeneazo)benzoic acid (HABA) and 3-n-pentadecyl phenol (PDP), via hydrogen bonds. The choice of an additive and a solvent is a key factor which influences the morphologies of the PS-PVP+HABA associates (supramolecular assemblies) in thin films. The reversible association via hydrogen bonds allows the amphiphilic molecules of PDP to phase segregate on the free air interface. Unlike, the molecules of HABA remain associated within cylindrical and lamellar domains formed by the PVP block. A solvent used for film deposition influences the orientation of PVP+HABA domains with respect to the confining interfaces. The films deposited from 1,4-dioxane – a good solvent for PS and a bad one for PVP+HABA – demonstrated the perpendicular orientation of PVP+HABA domains. Meanwhile, the preparation of films from a chloroform solution – a good solvent for both PS and PVP+HABA – led to the parallel alignment. The orientation was independent on the film thickness (within the studied range of 20–100 nm) and insensitive to the chemical nature of a substrate. The orientation of the domains was shown to switch upon exposure to vapors of the above mentioned solvents from the parallel to perpendicular orientation and vice versa. Moreover, the swelling of the films in solvent vapors resulted in the significant improvement of the domain ordering. Extraction of HABA with selective solvent transformed of PVP+HABA domains into channels with reactive PVP chains on the walls. The resulted membranes with the perpendicular oriented channels (the diameter about 8 nm, the inter-channel distance 24 nm) were used as a template for the creation of ordered arrays of nanodots from nickel, chromium and gold.

Page generated in 0.0504 seconds