Search results for "PHIP"
showing 10 items of 438 documents
Poly(ethylene oxide)-block-poly(n-butyl acrylate)-block-poly(acrylic acid) triblock terpolymers with highly asymmetric hydrophilic blocks: synthesis …
2013
The synthesis and aggregation behaviour in aqueous media of novel amphiphilic poly(ethylene oxide)-block-poly(n-butyl acrylate)-block-poly(acrylic acid) (PEO–PnBA–PAA) triblock terpolymers were studied. Terpolymers composed of two highly asymmetric hydrophilic PEO (113 monomer units) and PAA (10–17 units) blocks, and a longer soft hydrophobic PnBA block (163 or 223 units) were synthesized by atom transfer radical polymerisation (ATRP) of n-butyl acrylate and tert-butyl acrylate (tBA), followed by selective hydrolysis of the PtBA blocks. These terpolymers are not directly soluble in water but form defined spherical micelles by employing the dialysis method as confirmed by dynamic light scatt…
Design of nonionic surfactants for supercritical carbon dioxide
1996
Interfacially active block copolymer amphiphiles have been synthesized and their self-assembly into micelles in supercritical carbon dioxide (CO 2 ) has been demonstrated with small-angle neutron scattering (SANS). These materials establish the design criteria for molecularly engineered surfactants that can stabilize and disperse otherwise insoluble matter into a CO 2 continuous phase. Polystyrene- b -poly(1,1-dihydroperfluorooctyl acrylate) copolymers self-assembled into polydisperse core-shell-type micelles as a result of the disparate solubility characteristics of the different block segments in CO 2 . These nonionic surfactants for CO 2 were shown by SANS to be capable of emulsifying u…
Buildup of Ultrathin Multilayer Films by a Self-Assembly Process: II. Consecutive Adsorption of Anionic and Cationic Bipolar Amphiphiles and Polyelec…
1991
We have recently reported on the consecutive physisorption of anionic and cationic bipolar amphiphiles onto charged surfaces, adsorbed out of aqueous solutions [1]. Here, we extend our previous concept to multipolar compounds such as polyelectrolytes. In contrast to the bipolar amphiphile system, it is not necessary to separate single charges by a rigid unit, when the polyelectrolyte is adsorbed from sufficiently concentrated solutions. In this case the physisorbed layer does not bind with all ionic groups to the surface and exposes free ionic groups at the new film/solution interface. Therefore a polyelectrolyte layer can replace a layer of bipolar amphiphiles in the consecutive buildup of…
Supramolecular Aggregates in Vacuum: Positively Mono-Charged Sodium Alkanesulfonate Clusters
2010
The formation and structural features of positively mono-charged aggregates of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and sodium methane—(MetS), butane—(ButS) and octane—(OctS) sulfonate molecules in the gas phase have been investigated by electrospray ionization mass spectrometry, energy-resolved mass spectrometry and density functional theory (DFT) calculations. The experimental results show that the center-of-mass collision energy required to dissociate 50% of these mono-charged aggregates scantly depends on the length of the alkyl chain as well as on the aggregation number. This, together with the large predominance of mono-charged species in the mass spectra, was rationalized i…
Organized assemblies of magnetic clusters
2003
Abstract In this work we have explored the possibilities to create layered organizations of the Mn 12 single-molecule magnets using the Langmuir–Blodgett technique or attaching these clusters onto a metal surface by preparing self-assembled monolayers (SAMs). In the first part we discuss the use of the Langmuir–Blodgett (LB) technique in order to obtain organized magnetic films formed by monolayers of these clusters. Two strategies have been used with this aim. The first one consists of mixing Mn 12 acetate or benzoate derivatives with an amphiphile, while the second procedure is based on the use of Mn 12 derivatives specifically designed to form LB films. An alternative method is that of p…
Microspectroscopy on single domains of phase-separated monolayers
1989
SUMMARY A versatile and inexpensive, but fully equipped apparatus is presented, which enables detailed optical studies on amphiphilic molecules at the liquid-gas interface. Structural and spectroscopic information, particularly in small areas of single domains of phase-separated monolayers, can be achieved by combination of this miniaturized Langmuir trough and spectralphotometer microscope. The potential of this apparatus is demonstrated with some measurements on a diyne-substituted polymerizable lipid analogue at the air-water interface.
Immobilization of functionalized lipids in a random poly(methacrylate) copolymer monolayer
1995
It is shown that a monolayer of random poly(methacrylate) copolymer with a hydrophobic and a hydrophilic substituent exhibits a transition from the fluid to amorphous state. Above this transition any amphiphilic molecules mixed with the monolayer are immobile. Furthermore, such functionalized lipids are immobilized in the monolayer during the Langmuir-Blodgett transfer. The hydrophilic head-groups of the biotin-lipids remain on the formerly water-adjacent side of the monolayer, even if this side is exposed to air
How self-assembly of amphiphilic molecules can generate complexity in the nanoscale
2015
Abstract Given the importance of nanomaterials and nanostructures in modern technology, in the past decades much effort has been directed to set up efficient bottom up protocols for the piloted self-assembly of molecules. However, molecules are generally disinclined to adopt the desired structural organization because they behave according to their own specific intermolecular interactions. Thus, only some selected classes of chemical compounds are capable to lead to useful self-assembled structures. Amphiphiles, simultaneously possessing polar and apolar moieties within their molecular architecture, can give a wide scenario of possible intermolecular interactions: polar–polar, polar–apolar,…
Optical Studies of Amphiphilic Molecules with Interesting Electro-Optical and Non-Linear Optical Properties
1990
Structural control is a major issue in both life science, investigating the function of the biological machinery, and in materials science, aiming at the design of novel devices. In part one, recent electro-optical investigations of the primary event of photosynthesis on purified protein preparations are described. Part two focuses on structural studies of monolayers at an air/water interface, and of Langmuir-Blodgett multilayers from a new molecule designed for nonlinear optical applications.