Search results for "Amphiphile"
showing 10 items of 270 documents
The influence of hydrophobic substitution on self-association of poly(ethylene oxide)-b-poly(n-alkyl glycidyl carbamate)s-b-poly(ethylene oxide) trib…
2007
Abstract A series of amphiphilic poly(ethylene oxide)-b-poly(n-alkyl glycidyl carbamate)s-b-poly(ethylene oxide) triblock copolymers were synthesized by reaction between poly(ethylene oxide)-b-polyglycidol-b-poly(ethylene oxide) precursor copolymer and four n-alkyl isocyanates: ethyl, propyl, butyl and pentyl. After dissolution in water at room temperature the copolymers spontaneously form micelles. The critical micellization concentrations were determined by UV–VIS spectroscopy. The dimensions of the micelles, the aggregation numbers, and in some cases the micellar shape were determined by dynamic and static light scattering in a relatively broad temperature range. Special attention has be…
Langmuir and Langmuir-Blodgett films of multifunctional, amphiphilic polyethers with cholesterol moieties.
2010
Langmuir films of multifunctional, hydrophilic polyethers containing a hydrophobic cholesterol group (Ch) were studied by surface pressure-mean molecular area (π-mmA) measurements and Brewster angle microscopy (BAM). The polyethers were either homopolymers or diblock copolymers of linear poly(glycerol) (lPG), linear poly(glyceryl glycidyl ether) (lPGG), linear poly(ethylene glycol) (lPEG), or hyperbranched poly(glycerol) (hbPG). Surface pressure measurements revealed that the homopolymers lPG and hbPG did not stay at the water surface after spreading and solvent evaporation, in contrast to lPEG. Because of the incorporation of the Ch group in the polymer structure, stable Langmuir films wer…
Polymeric Micelles and Liposomes as Potential Drug Carriers
1986
In the past, a whole aray of polymeric carriers for biologically active substances have been reported. In this field the main interest has focused on the use of randomly solubilized polymers. Naturally occuring amphiphilic transport proteins can be modelled by synthetic micellar solubilized polymers. Poly(ethylene oxide)-polypeptide block copolymers with hydrophobic and cyclophosphamide-containing side groups are described. These micellar systems are able to transport different hydrophobic drugs.
Self-organization of amphiphilic N-acylated linear polyethyleneimines: investigation of a reversible monolayer collapse
1996
Abstract Poly-N-4-decyloxybenzoylethyleneimine, highly crystalline in bulk, forms a stable monolayer at the air-water interface which undergoes a reversible collapse into a probable bilayer structure at higher surface pressures. We achieved transfer both from the monolayer and “bilayer” region of the polymer film at the water surface onto hydrophilic and hydrophobized quartz supports. Based on X-ray investigations on the deposited Langmuir-Blodgett films, a possible mechanism for the reversible collapse is proposed.
Defects and defect engineering in Soft Matter.
2020
Soft matter covers a wide range of materials based on linear or branched polymers, gels and rubbers, amphiphilic (macro)molecules, colloids, and self-assembled structures. These materials have applications in various industries, all highly important for our daily life, and they control all biological functions; therefore, controlling and tailoring their properties is crucial. One way to approach this target is defect engineering, which aims to control defects in the material's structure, and/or to purposely add defects into it to trigger specific functions. While this approach has been a striking success story in crystalline inorganic hard matter, both for mechanical and electronic properti…
Polymeric amphiphiles with hydrophilic main chain spacers: Studies in monolayers and Langmuir-Blodgett multilayers
1988
A methacrylic lipid was polymerized to form an amphiphilic homopolymer and random copolymers with various levels of acrylic acid comonomers. The behavior of these polymeric lipids was investigated in monolayers at the air-water interface and in Langmuir-Blodgett multilayers on polymer foil supports. The acrylic acid acts as a hydrophilic spacer along the polymer backbone, and improves the ability of the polymer to self-organize into highly ordered monolayers and ultimately LB multilayers. It is shown that the quality and stability of the multilayers increase substantially with the increase in comonomer content.
Specialty and advanced polymers by carbocationic macromolecular engineering
1993
This study briefly surveys a variety of new advanced polymeric materials and controlled synthetic processes available by carbocationic macromolecular engineering techniques and having potential commercial interest. These recent developments, mainly by living carbocationic polymerization, have led to new opportunities in polymerization process control, and in designing microstructure, functionality, molecular weight and molecular weight distribution (MWD) and thus properties of a wide variety of unique polymer systems. The fundamentals of these new emerging technologies and the novel materials offered by them, such as macromonomers, telechelics, polymers with pendant functional groups (liqui…
Tunable dynamic hydrophobic attachment of guest molecules in amphiphilic core–shell polymers
2016
In this study, synthesis and dynamic properties of amphiphilic core–shell polymers are reported as monitored through their interaction with small amphiphilic molecules. Brush-like structures are formed with a hydrophobic core surrounded by a hydrophilic shell utilizing controlled radical addition–fragmentation chain transfer (RAFT) polymerization of macromonomers consisting of linear polyglycerol chains attached to alkylene methacrylate. Continuous wave electron paramagnetic resonance (CW EPR) spectroscopy is employed to study how the amphiphilic, paramagnetic spin probe 16-DSA (16-doxyl stearic acid) interacts with polymers of different alkylene chain lengths in their hydrophobic cores and…
Synthesis strategies and properties of smart amphiphilic networks
1996
This paper briefly surveys recent developments in the field of amphiphilic networks (APN) which are a new class of crosslinked polymer systems consisting of covalently bonded hydrophobic and hydrophilic chain segments. The covalent bonds between immiscible hydrophobic and hydrophilic polymer chains prevent demixing and yield polymer networks with unique structure and properties. Telechelic macromonomers provide the basis for the first generation of APNs obtained by copolymerization of the macromonomer with selected low molecular weight monomers. Synthesis of a variety of APNs using methacrylate-telechelic polyisobutylene (PIB) macromonomers prepared by living carbocationic polymerization (L…
Micelles Formed by Cylindrical Brush-Coil Block Copolymers
2005
Amphiphilic cylindrical brush-coil block copolymers consisting of a polystyrene coil and a cylindrical brush block with poly(acrylic acid) side chains are prepared by ATRP of t-butylacrylate from a block comacroinitiator. Upon acidolysis of the poly(t-butylacrylate), water-soluble polymers were obtained that were observed to form micelles consisting of 4-5 block copolymers on average in aqueous solution. The star-like nature of such micelles was clearly visualized by scanning force microscopy.