Homogeneous mixtures of polybetaines with low molecular weight salts
The prepaparation of amorphous, homogeneous blends of zwitterionic polymers with various low molecular weight salts, and in particular with ionic dyes was studied. Homogeneous miscibility was achieved in many cases up to equimolar amounts of salt, even for bulky compounds. Whether miscibility is achieved, or not, depends in a subtle way on the chemical structure of the salt, but no obvious correlation between structure and miscibility could yet be revealed. Spectral shifts of the dye UV/Vis spectra in solution as well as in bulk suggest strong interactions between the polybetaines and the admired salts.
Amphiphilic dyes for NLO in LB-films
The influence of structural variations of phenyl-hydrazones and stilbazium salts on monolayer behaviour and second-harmonic generation in LB-monolayers is discussed. In contrast to the stilbazium salts the variation of the substituents of the phenylhydrazones does not influence the absorption maximum of the dyes in resonance enhancement of the nonlinearity. This allows a direct comparison of the substitution pattern on SHG.
Macromolecular complexes. Dynamic interactions and electronic processes. Edited byEishun Tsuchida, VCH, Weinheim 1991, vi, 400 pp., hardcover, DM 225.-, ISBN 0- 89573-784-1
Several zwitterionic polymers were prepared by radical homopolymerization of surfactant monomers which bear diallyl, diene or vinylcyclopropane moieties. These polymer systems were complemented by alternating copolymers of appropriate zwitterionic vinyl compounds. Thus, polymers with reduced (as compared with simple vinylic homopolymers, or statistical copolymers) and well defined density of surfactant side groups are obtained. The solubilities found for these polymers are dominated by polymer geometry rather than by the balance of hydrophilic and hydrophobic fragments, thus corroborating a “main-chain spacer” model proposed recently. All water-soluble polymers exhibit characteristic featur…
The polysoaps [CH 2 C(Me)(CO 2 R)] n (R=(CH 2 ) 11 N + Me 2 (CH 2 ) 3 SO 3 − , (CH 2 ) 11 N + Me 2 CH 2 CH 2 OH) are studied. Their aqueous solution properties are strongly influenced by added salts; the surface activity can be modified efficiently by an appropriate choice of ions. The interactions of salts and polyzwitterions observed in solution can be extended to the behaviour in bulk. It enables the preparation of uniform, non crystalline blends containing up to equivalent amounts of inorganic salt and polyzwitterions
Structure and Reactivity in Reverse Micelles. (Reihe: Studies in Physical and Theoretical Chemistry, Vol. 65). Von M. P.Pileni Herausgegeben Elsevier, Amsterdam 1989. XVIII, 379 S., geb. Hfl. 285.00. — ISBN 0–444–88166–2
Investigations of polymerizable multilayers as gas separation membranes
Abstract Polymerizable Langmuir—Blodgett (LB) multilayers of several diacetylenic amphiphiles were investigated on gas-permeable, polymeric supports. Macroscopically homogeneous multilayer films of hexacosa-10,12-diynoic acid and pentacosa-10,12-diyne phosphonate could be built up on polypropylene and polytetrafluoroethylene materials. As shown by scanning electron microscopy, the microscopic homogeneity of the built-up multilayers was mainly controlled by the surface structure of the support material, whereas the chemical nature of the support and photopolymerization of the layers did not affect the high order of the films. Such LB multilayers deposited on porous support materials are able…
Characterization of sulfobetaine monomers by nuclear magnetic resonance spectroscopy: a note
A set of zwitterionic monomers bearing the 3-ammoniopropanesulfonate moiety is analysed in CDCl3, CD3OD and D2O by one- and two-dimensional H-1 n.m.r. and C-13 n.m.r. spectroscopy. Absolute and relative positions of the n.m.r, signals are determined depending on the solvent used; the refined assignments of the signals in the vicinity of the ammonium group deviate from previously proposed assignments based on standard n.m.r, shift tables. Still, there is no convincing evidence for a special ring current effect due to a six-membered ring conformation of the betaine moiety.
Structure and properties of zwitterionic polysoaps: functionalization by redox-switchable moieties
Redoxactive monomeric and polymeric surfactants containing viologen and N-alkylated nicotinic acid moieties were synthesized. These systems are potentially able to trigger reversible changes of self-organization by creation or removal of a charge via a redox reaction. Hence, they are investigated with respect to solubility, aggregation behavior, and their electrochemical properties in water. — All monomers, but only the viologen polymers are water-soluble and drastically decrease the surface tension of water. Critical micelle concentrations are observed for the monomers only. — The chemical reversibility of the redox reactions of the compounds in water was investigated using cyclic voltamme…
Hybrid materials from organic polymers and inorganic salts
The prepaparation of amorphous, homogeneous blends of zwitterionic polymers and transition metal salts was investigated. Homogeneous miscibility was achieved in many cases up to equimolar amounts of salt, depending on the anion and cation chosen. Various analytical techniques point to a solid state solution of the inorganic ions in the polymer matrix.
Recent achievements in the field of micellar polymers, or «polysoaps» are described. Taking advantage of zwitterionic model polymers, systematic variations of the molecular architecture have provided an improved understanding of the relationship between the molecular structure of the polymers and their key properties such as surface activity and solubilization capacity. Useful rules are established, which take into account much of the previous data in the literature
Polymerizable and polymeric zwitterionic surfactants: 2. Surface activity and aggregation behaviour in aqueous systems
Abstract The surfactant properties of a series of permanently zwitterionic monomers and polymers were studied with respect to structural variations. A strong influence of the molecular geometry on solubility and aggregation behaviour was observed, in particular for the polymers. Whereas all monomers were water-soluble and true surfactants, the water solubility of the polymers was restricted to selected geometries. Water-soluble polymers showed the properties of classical polysoaps, i.e. low surface activity and solubilization power for hydrophobic solutes. In contrast, water-insoluble polymers formed stable monolayers at the air-water interface and could be deposited onto solid substrates b…
ChemInform Abstract: Monolayers and Langmuir-Blodgett Multilayers of Discotic Liquid Crystals?
The field of monolayer and multilayer films of discotic LCs is at its very beginning. The scope and limitations of this preparation method have not yet been explored, and little is known about the structures obtainable. However, the potential access to extraordinary, ordered thin films is fascinating, and will stimulate research in the future.
Solubilization control by redox-switching of polysoaps
Reversible changes in the self-organization of polysoaps may be induced by controlling their charge numbers via covalently bound redox moieties. This is illustrated with two viologen polysoaps, which in response to an electrochemical stimulus, change their solubility and aggregation in water, leading from homogeneously dissolved and aggregated molecules to collapsed ones and vice verse. Using the electrochemical quartz crystal microbalance (EQCM), it could be shown that the reversibility of this process is better than 95% in 16 cycles.
The molecular packing and spatial correlations of polymers [CH 2 CR(COOR')] n (R= H, Me; R'= (CH 2 ) 11 + NMe 2 (CH 2 ) 3 SO 3 - ; (CH 2 ) 2 + N(Me)[(CH 2 ) 3 SO 3 - ][C 10 H 21 ]) are studied by means of X-ray analysis and conformational calculations. The analysis of the correlation functions and density distribution profiles suggest a double-layered molecular packing which is discussed for the three polymers investigated, with respect to their different chemical structures. Whereas the zwitterionic polymethacrylates studied exhibit liquid-like short-range order, the polyacrylate analog exhibits an ordered double-layered superstructure
Polymerizable and polymeric zwitterionic surfactants: 1. Synthesis and bulk properties
Abstract The synthesis of a series of permanently zwitterionic surfactant monomers based on sulphobetaines and the preparation of their polymers is described. Solubilities, thermal properties and bulk structures of the zwitterionic polymers are studied with respect to their molecular architecture, and compared with cationic analogues. The various solubilities of the polymers can be correlated with their molecular geometry, enabling differentiation into distinct classes. This behaviour is paralleled by the observed bulk structures of the polymers where distinct classes of superstructures are present. However, independently of the molecular geometry, no thermal transition could be detected fo…
Monolayers and Langmuir-Blodgett Multilayers of Discotic Liquid Crystals?
The field of monolayer and multilayer films of discotic LCs is at its very beginning. The scope and limitations of this preparation method have not yet been explored, and little is known about the structures obtainable. However, the potential access to extraordinary, ordered thin films is fascinating, and will stimulate research in the future.
Cinnamic acid moieties were incorporated into amphiphilic compounds containing one and two alkyl chains. These lipid-like compounds with photoreactive units undergo self-organization to form monolayers at the gas-water interface and bilayer structures (vesicles) in aqueous solutions. The photoreaction of the cinnamic acid moiety induced by 254 nm UV light was investigated in the crystalline state, in monolayers, in vesicles and in solution in organic solvents. The single-chain amphiphiles undergo dimerization to yield photoproducts with twice the molecular weight of the corresponding monomers in organized systems. The photoreaction of amphiphiles containing two cinnamic acid groups occurs v…
Monolayers of rod-shaped and disc-shaped liquid crystalline compounds at the air-water interface
Calamitic (rod-shaped) and discotic (disc-shaped) thermotropic liquid crystalline (LC) compounds were spread at the air-water interface, and their ability to form monolayers was studied. The calamitic LCs investigated were found to form monolayers which behave analogously to conventional amphiphiles such as fatty acids. The spreading of the discotic LCs produced monolayers as well, but with a behaviour different from classical amphiphiles. The areas occupied per molecule are too small to allow the contact of all hydrophilic groups with the water surface and the packing of all hydrophobic chains. Various molecular arrangements of the discotics at the water surface to fit the spreading data a…
ChemInform Abstract: Preformed Polymers for Langmuir-Blodgett Films - Molecular Concepts
The use of preformed polymers for the preparation of Langmuir-Blodgett (LB) multilayers is reviewed. Principles for polymer self-organization are outlined and the appropriate molecular designs are discussed. Recent developments in the different classes of polymers for LB multilayers are presented, and their outstanding properties highlighted.
Second-harmonic generation in Langmuir–Blodgett monolayers of stilbazium salt and phenylhydrazone dyes
The second-order nonlinear optical susceptibilities χ(2) of several phenylhydrazone and stilbazium salt dyes in Langmuir–Blodgett monolayers have been determined from second-harmonic-generation measurements. Three of the substances demonstrated χ(2) values greater than 10−6 electrostatic units, although two of the three did not absorb light significantly at the second-harmonic wavelength.
Book Review: Structure and Reactivity in Reverse Micelles.(Series: Studies in Physical and Theoretical Chemistry, Vol. 65). Edited by M. P. Pileni
Adsorption properties of soluble surface active stilbazium dyes at the air-water interface
The adsorption behaviour of a homologous series of amphiphilic hemicyanines is studied at the air-water interface. The dyes exhibit an unusual, marked odd-even effect with respect to the standard free energy of adsorption and the minimum surface area demand. The reasons for such strong, hitherto unknown odd-even effect is not yet clear.
Relaxation and charge transport in mixtures of zwitterionic polymers and inorganic salts
Dielectric spectroscopy is employed to analyze the molecular dynamics and the charge transport in mixtures of zwitterionic polymers of the type poly(3-[N-(omega-methacryloyloxyalkyl)-N, N-dimethylammonio]propanesulfonate) with sodium iodide in the frequency range of 10(2) Hz-10(7) Hz and in the temperature range of 110 K-400 K. The amount of inorganic salt added varies from 0-200 mol-% relative to the number of zwitterionic groups present in the polymer, contributing strongly to the conductivity. One relaxation process is observed whose relaxation rate depends strongly on the length of the aliphatic spacer between the polymethacrylate main chain and the zwitterionic group. Exhibiting an Arr…
Material transport and organizing phenomena of Langmuir—Blodgett membranes from polymerizable built up diacetylene amphiphiles on hydrophobic supports
Abstract Langmuir—Blodgett multilayers of polymerized diin amphiphiles on different porous, hydrophobic ultrafilters have been studied as composite membranes under the conditions of reverse osmosis. Influences of differently structured surfaces of the supports on structure and phase change occurring during polymerization have been investigated by scanning electron microscopy and X-ray diffraction and are discussed with reverse osmosis data. When conditioned, fine porous hydrophobic supports become permeable to aqueous solutions at low pressures. Under these conditions permeate flux and retention were found to depend on the number of layers deposited.
Self-organization of hydrophobized polyzwitterions
Abstract Several series of copolymers of different geometry were synthesized from zwitterionic surfactant monomers and polar non-ionic comonomers. Bulk properties were investigated by d.s.c. and X-ray scattering. The copolymers were amorphous, but exhibited superstructures up to high commonomer contents. Solubility of the copolymers was determined as a function of geometry and composition. From the results, a main chain spacer model has been derived. All water-soluble copolymers exhibited characteristic features of classical polysoaps, as shown by surface tension measurements and by solubilization of pyrene. But gradual differences depending on the polymer geometry were observed for the sol…
ChemInform Abstract: Amphiphilic Dyes for Nonlinear Optics: Dependence of Second Harmonic Generation on Functional Group Substitution.
Molecular Recognition by Hydrogen Bonding in Polyelectrolyte Multilayers
Functional polyanions were prepared by copolymerization of sulfopropyl acrylate and sulfopropyl methacrylate with monomers bearing triaminopyrimidine or barbituric acid functionalities, respectively. Functionalized polyelectrolyte multilayers were assembled from these copolymers by stepwise alternating adsorption with poly(choline methacrylate). These multilayers are suited for molecular recognition of substrates that are complementary to the functional groups incorporated. Thus, multilayers containing triaminopyrimidine moieties selectively bind barbituric acid, and vice versa, when exposed to solutions of the 1:1 complex of barbituric acid and triaminopyrimidine. The molecular recognition…
Quadratic Nonlinear Behaviour of Various Langmuir-Blodgett Molecules
The Langmuir-Blodgett (L-B) technique is well known as a method of building-up ordered arrays of organic molecules, and especially as a means of imposing a noncentrosymmetric structure from molecules that crystallize in a centrosymmetric space group(1–3). L-B films for use in quadratic nonlinear optics can be ordered in a statistically noncentrosymmetric lattice. The method involves the compression of a mono-layer of the organic molecule, spread on top of a water surface, into a two-dimensional solid, followed by the repeated dipping of the substrate to be coated into and out of the subphase. Monolayers may be deposited onto the substrate both on immersion and withdrawal, resulting in a cen…
Mixed polymeric monolayers and Langmuir-Blodgett multilayers with functional low molecular weight guest compounds
Abstract Mixed monolayers and Langmuir-Blodgett multilayers of functional low molecular weight guest compounds, especially nonlinear optical (NLO) dyes, within the matrix of an amphotropic spacer polymer have been prepared. The polymer matrix enabled the transfer of guest compounds not capable of self-organizing at the air-water interface by themselves. The structure of the LB multilayers and the transfer process were studied by small angle X-ray scattering and UV-visible spectroscopy. Good NLO coefficients were found in the mixed films.
Oligoethyleneoxide spacer groups in polymerizable surfactants
Cationic and zwitterionic polymerizable surfactants bearing tri- and tetraethyleneglycol spacer groups between the polymerizable moiety and the surfactant structure were prepared and polymerized. Monomers and polymers were investigated with respect to their aggregation behavior in aqueous systems and compared to analogous monomers and polymers lacking spacer groups. In the case of the monomeric surfactants, the spacer groups depress both the Kraffttemperature and the critical micelle concentration. the area occupied per molecule at the air-water interface is substantially enlarged by the spacers, whereas the depression of surface tension is nearly constant. Although the monomers with and wi…
Preparation des polymeres (CHR-CH 2 SO 2 ) (R=(CH 2 ) 9 N + Me 2 (CH 2 ) 3 SO 3 − , (CH 2 ) 8 CO[NC 4 H 8 N + (Me)([CH 2 ] 3 SO 3 − )] et R=CH 2 OCH 2 CHOHCH 2 N + Me(C 10 H 21 )(CH 2 ) 3 SO 3 − ) par copolymerisation spontanee des sels d'ammonium vinyliques correspondants avec SO 2 dans l'eau. Leurs proprietes de surface et de solubilisation de molecules hydrophobes en solution aqueuse sont caracteristiques de polysavons
Solubilization by polysoaps
The aqueous solubilization power of several series of micellar homopolymers and copolymers (''polysoaps'') is investigated. Using five insoluble or poorly water-soluble dyes, comparisons of the capacities are made with respect to the influence of structural variables such as the polymer backbone, the polymer geometry, the comonomer content, and the charge of the hydrophilic group. Some guidelines for polysoap structures suited for efficient solubilization are established. Noteworthy is that the solubilization capacities of the polysoaps are neither linked to the ability to reduce the surface tension of water, nor to the polarity of the solubilization sites deduced from spectroscopic probes.
Zwitterionic polymers [CH 2 CR(COOR')] n (R= H, Me; R'= (CH 2 ) 11 + NMe 2 (CH 2 ) 3 SO 3 - , (CH 2 ) 2 + N(CH 3 )([CH 2 ] 3 SO 3 - )C 10 H 21 ) are studied by X-ray scattering. The structural order both in the short-range and long-range scale is investigated. The influence of the polymer backbone, of different locations of the ionic groups in isomeric polymers, of bound water and of added inorganic salts on the bulk structures is studied, and the observed rearrangements are analysed
Preformed polymers for Langmuir-Blodgett films- molecular concepts
The use of preformed polymers for the preparation of Langmuir-Blodgett (LB) multilayers is reviewed. Principles for polymer self-organization are outlined and the appropriate molecular designs are discussed. Recent developments in the different classes of polymers for LB multilayers are presented, and their outstanding properties highlighted.