Solvophilic

In fact, the orientation of water at the potential of zero charge is expected to depend approximately linearly on the electronegativity of the metal.9 This orientation (see below) may be deduced from analysis of the variation of the potential drop across the interface with surface charge for different metals and electrolytes. Such analysis leads to the establishment of a hydrophilicity scale of the metals ( solvophilicity for nonaqueous solvents) which expresses the relative strengths of metal-solvent interaction, as well as the relative reactivities of the different metals to oxygen.23... 

In addition, medium effects play an important role through the interaction of solvent molecules with p and a as well as with each other thus the two partners should present geometrically matched hydrophobic/hydrophobic or hydrophilic/hydro-philic (solvophobic, solvophilic, more generally) domains. 

The -conjugated achiral oligo(m-phenylene ethynylene) 60 (Fig. 20) adopts a random conformation in solvophilic solvents such as chloroform,... 

Dendrons attached as side chains on linear polymer chains behave different from free dendrimers and dendrons. Block copolymers, poly(3,5-bis(3,5-bis (benzyloxy)benzyloxy)-benzyl methacrylate-random-methacrylic acid)-block-poly(2-perfluorooctylethyl acrylate), possess poly(benzylether) dendrons and perfluorinated alkyl chains in their side chains (Fig. 4) [85], While an LB film of a copolymer with a medium substitution fraction of poly(benzylether) dendron side chain in poly(methacrylic acid) displays flat surface, a copolymer with high fraction of poly(benzylether) dendron side chains produces the zone texture. Dendron rich blocks are hydrophobic and oleophilic but perfluorinated blocks are solvophobic. Therefore, in this case, the solvophobicity-to-solvophilicity balance must be considered. As a result, copolymers with medium fraction of dendron are laid on solid substrate, but dendron blocks of copolymers with high fraction prefer to arrange at air side of air/ water interface and the fluorocarbon blocks are enforced to exist close to water subphase, resulting in the zone texture [86]. These situations of molecular arrangements at air/water interface are kept even after transfer on solid substrate. By contrast, when perfluorooctadecanoic acids are mixed with block copolymers with high dendron fraction, the flat monolayers are visualized as terrace [87], The monolayers are hierarchized into carboxyl, per-fluoroalkyl, and dendron layers, that is, hydrophilic, solvophobic, and oleophilic layers. In this case, perfluorooctadecanoic acids play a role for ordering of block copolymers. 

The driving force for the formation of the hpid bilayer structure is the amphiphiUcity of the component molecules one part of the molecule is soluble in a particular solvent while the other has a low affinity to the solvent. If this concept is extended, the use of water as a medium is not a necessary condition of bilayer structure formation. Reversed micelles are formed in organic solvents. Are bilayer structures also formed in organic solvent This is an important question regarding the fundamental nature of amphiphilicity and the abihty to extend the applicability of amphiphile assembhes to various fields. The answer to this question is yes . Some compounds with a fluorocarbon part and a hydrocarbon part can form bilayer-like assemblies in organic solvent. The fluorocarbon part has a low affinity to the organic solvent and has a solvophobic nature, hi contrast, solvophilic characteristics are exhibited by the hydrocarbon parts. As shown in Fig. 4.30, these amphiphilic molecules assemble in order to expose the solvophilic part to the solvent and to hide the solvophobic part inside the assembly. If there is a good structural balance between the solvophilic part... 

On the other hand, long-chain oligo(ethylene oxides) in hydrophobic SAMS reject biopolymers, e.g. proteins. Stabilization of colloids by solvophilic polymers can be explained by a concept called steric repulsion which means disfavourable compression and resulting loss of chain mobilities in colliding polymers. 

In this context we note that the formation of nanostructures by amphiphilic molecules represents a careful balance between the solvophobic and the solvophilic interactions. A dominance of either can lead to either phase separation or complete solubility of the amphiphile in the solvent. While the subtle balance between these forces is recognized in the current literature, the crossover from one behavior to the next remains to be understood in a quantitative fashion. 

Figure 1 Schematic drawing of the various types of surfactants used in the molecular dynamics (MD) simulations discussed in this chapter. The lighter spheres represent solvophilic beads (solvent bead or head bead), and the darker spheres are the solvophobic beads (tail bead or oil bead).

Mattice and coworkers performed their simulations of diblock copolymer micellization on a cubic lattice, typically of dimensions 44 x 44 x 44 and with a coordination number of c = 6. As in the case of Larson s model, only one energy parameter, f, is considered for all interactions, namely, the interaction between the tail and the solvophilic (head and solvent) beads. The base structure used for the copolymer is hiQtio. The chains are rearranged using reptation and Verdier-Stockmayer [53] type local motions, both of which are discussed in detail in Sec. III. C. Wijmans and Linse [50] also based their simulations on this model and surfactant structure. 

Figure 9 Free surfactant concentration versus total surfactant concentration for several values of the solvophilic strength C-The line of unit slope is shown for reference (dashed line). Lines through the high concentration regions are shown to guide the eyes. The points of intersection of these lines with the dashed line give the respective erne s. (From Ref. 31.)...

Figure 10 The dependence of the aggregate size distribution on solvophilic strength C for a solution of / it3. (From Ref 31.)...

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