Dynamic colloid morphology

Colloid morphology, especially its dynamic variant, is still in its very beginnings, but the author thought that a survey of results obtained with coacervates (Ch. XI) might stimulate its further, development. 

The tasks of colloid morphology and its two subdivisions, static and dynamic colloid morphology have already been expounded in brief outline in chapter I. 

In this first we deal mainly with morphological systems in equilibrium (static colloid morphology), in the succeeding morphological changes of state (dynamic colloid morphology) are more prominent. 

The phenomena which are exhibited by complex coacervate drops in an electric field (type dicomplex coacervates p. 345, Ch. X, 2e) furnish a fairly complicated case for study in dynamic colloid morphology (p. 17). Here we encounter ... 

The method sketched above can be used with advantage in the study of dynamic colloid morphology in which we are set the task of studying the path morphologically followed from one equilibrium state to another as well as investigating the reversibility of this path. 

Now dynamic colloid morphology studies the path along which a colloid system proceeds from the one equilibrium state (here coacervate spread out over... 

Block copolymers in selective solvents exhibit a remarkable capacity to self-assemble into a great variety of micellar structures. The final morphology depends on the molecular architecture, tlie block composition, and the affinity of the solvent for the different blocks. The solvophobic blocks constitute the core of the micelles, while the soluble blocks form a soft and deformable corona (Fig. Id). Because of this architecture, micelles are partially Impenetrable, just like colloids, but at the same time inherently soft and deformable like polymers. Most of their properties result from this subtle interplay between colloid-like and polymer-like features. In applications, micelles are used to solubilize in solvents otherwise insoluble compounds, to compatibilize polymer blends, to stabilize colloidal particles, and to control tire rheology of complex fluids in various formulations. A rich literature describes the phase behavior, the structure, the dynamics, and the applications of block-copolymer micelles both in aqueous and organic solvents [65-67],... 

The microstructure and particle morphology (size, shape, and surface roughness) of the colloids were studied with 13C and 29Si NMR spectroscopy, elemental analysis, transmission electron microscopy, and static and dynamic light scattering. 

With the increased level of understanding of the cyclization dynamics as monitored by intramolecular excimer fluorescence, it is now possible to extend this probe to the study of systems more complex than dilute solutions. One such situation involves the structure and dynamics of macromolecular complexes formed between polymeric proton donors and acceptors in aqueous solution. For example, there has been widespread interest in the complexes formed between poly(ethylene glycol) and poly(acrylic acid) or poly(methacrylic acid) in aqueous solution (34, 35). A second, complicated morphological problem is to describe the configurational behavior of polymer chains adsorbed on colloidal particles. This research has relevance to the understanding of steric stabilization. One system of particular interest is the interaction of poly(ethylene glycol) and colloidal silica (36-40). 

M. Gradzielski, Investigations of the dynamics of morphological transitions in amphiphilic systems. Curr. Opin. Colloid Interface Sci. 9, 256-263 (2004)... 

Benoit Mandelbrot (1924-2010). .. was a Polish-French mathematician who dealt with several math-related problems, e.g. in information theory, economics, and fluid dynamics. Mandelbrot won great renown through his publications on fractal objects, which inspired researchers of very different scientific fields. Soon after his seminal book on fractal structures in nature, science, and daily life, the idea of fractal dimension was adopted by colloid science to describe aggregation and aggregate morphology. 

In this section, we discuss theoretical and computational studies that provide insights into structural correlations and dynamical behavior of species in CLs. Structural complexity is an inherent trait of CLs. Advanced fabrication aims to improve Pt utilization by enhancing the interfacial area of Pt with water in pores and with Nafion ionomer [12, 94—95], A practical way to achieve this is by mixing ionomer with dispersed Pt/C catalysts in the ink suspension prior to deposition to form a CL. The solubility of the ionomer depends upon the choice of a dispersion medium. This influences the microstructure and pore size distribution of the CL [95]. Self-organization of ionomer and carbon/Pt in the colloidal ink leads to the formation of phase-segregated agglomerated morphologies. 

A. Ghatak, R. Khanna, and A. Sharma, Dynamics and morphology of holes in dewetting of thin films, / Colloid Interface Sci., 212, 483-494 [1999/... 

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