Confinement domain

Pulsed field gradient (PFG)-NMR experiments have been employed in the groups of Zawodzinski and Kreuer to measure the self-diffusivity of water in the membrane as a function of the water content. From QENS, the typical time and length scales of the molecular motions can be evaluated. It was observed that water mobility increases with water content up to almost bulk-like values above T 10, where the water content A = nn o/ nsojH is defined as the ratio of the number of moles of water molecules per moles of acid head groups (-SO3H). In Perrin et al., QENS data for hydrated Nation were analyzed with a Gaussian model for localized translational diffusion. Typical sizes of confining domains and diffusion coefficients, as well as characteristic times for the elementary jump processes, were obtained as functions of A the results were discussed with respect to membrane structure and sorption characteristics. ... 

The reduction of the long-range diffusivity, Di by a factor of four with respect to bulk water can be attributed to the random morphology of the nanoporous network (i.e., effects of connectivity and tortuosity of nanopores). For comparison, the water self-diffusion coefficient in Nafion measured by PFG-NMR is = 0.58 x 10 cm s at T = 15. Notice that PFG-NMR probes mobilities over length scales > 0.1 /rm. Comparison of QENS and PFG-NMR studies thus reveals that the local mobility of water in Nafion is almost bulk-like within the confined domains at the nanometer scale and that the effective water diffusivity decreases due to the channeling of water molecules through the network of randomly interconnected and tortuous water-filled domains. ... 

As the interface of two media, the surface is a confined domain which may catalyze intense activity—physicochemical reactions, charge-carrier generation, nonlinear optics—owing to the transition between the two phases and... 

It is apparent that these new structured clefts, struts, surfaces and enclosures in the 1-100 nm size range will have important roles as quantum confinement domains, receptors, containers, carriers, catalytic surfaces or scaffolding for molecular recognition in the emerging area of nanotechnology (see Ref. 183). 

Such a porosity formation via nucleation and subsequent aggregation of primary nuclei was described for the first time by Kun and Kunin [311] at the end of 1960s. However, later it was found [312-314] that, being prepared under slightly different conditions, macroporous resins may acquire an entirely different texture. Fig. 3.9a shows a schematic diagram initially suggested by Haupke and Pientka [312], in which, as a function of the DVB and diluent concentrations, two borderlines confine domain II where aU the above three levels of porosity may be observed. Below the lower boundary (domain I), where the concentrations of DVB and the diluent are smaller... 

The confined domains depicted in Fig. 5 represent the regions where macro-scopically homogeneous and single-phase systems are found. However, these domains do not necessarily represent micellar or microemulsion systems. 

A confined polymer system is defined [60,64,85,91] as a domain of polymers of reduced dimension which are independent from one another (e.g., droplet, cylinder, lamella, etc.). These confined polymers that are crystaltizable can experience confinement in one, two, or three dimension when the number of such a confined domain is of the same order of magnitude or higher than the number of active... 

The size of the confinement domain is defined as the side of a square in which diffusion is confined [22]. For details, see 23. 

In this study, extending the concept of localizing bubble nucleation in a confined domain, nanocellular foam was prepared with commodity polymer blends, polystyrene (PS) and poly (methyl methacrylate) (PMMA). The polymer blend was prepared by polymerizing methyl methacrylate (MMA) monomer in polystyrene matrix after dissolving the monomer into the matrix. The polymerization in polymer matrix provides highly dispersed PMMA domains. The polymer blend was then foamed by CO2. The effects of blend ratio, foaming temperature and depressurization rate on bubble diameter as well as bubble density were investigated. 

The method of polymerization in polymer matrix could provide a highly dispersed PMMA domain. Nanocellular foam was then created using the polymer blend and carbon dioxide. The bubble nucleation and cell size were controlled by the foaming temperature, and blend ratio of PS/MMA. The concept of localizing the bubble nucleation in confined domain was proved to one of the methods of creating nanocelluar foam Ifom commodity polymers. 

Figure C2.2.9. Polygonal domains of focal conics in a smectic A phase confined between parallel plates.

Consider a closed curve such that it confines the bounded simply connected domain Q c W T, and contains T, as a part of its boundary. According to the above the equations (2.142), (2.143) hold in Q, and hence... 

In Figure 2.6, the slips/mistakes distinction is further elaborated by relating it to the Rasmussen SRK classification of performance discussed earlier. Slips can be described as being due to misapplied competence because they are examples of the highly skilled, well practiced activities that are characteristic of the skill-based mode. Mistakes, on the other hand, are largely confined to the rule and knowledge-based domains. 

Hashimoto T., Shibayama M., Kawai H., and Meier D. J. Confined chain statistics of block polymers and estimation of optical anisotropy and domain size. Macromolecules, 18, 1855, 1985. 

G = G -b r and confine ourselves, for the sake of simplicity, to the case of a two-dimensional domain (p = 2). Here a constructive supposition about the shape of the domain G is taken into account that the intersection of the domain G with any straight line passing through an inner point x G in parallel to the coordinate axis Ox (a = 1,2) consists only of a finite number of intervals. 

The usual assumptions are made here saying that the boundary F is smooth enough and the intersection of the domain G and a straight line passing through any point x (E G and in parallel to the axes Ox, a = 1,2, consists of a unique interval. The latter should not confine generality. 

The effects of the intramicellar confinement of polar and amphiphilic species in nanoscopic domains dispersed in an apolar solvent on their physicochemical properties (electronic structure, density, dielectric constant, phase diagram, reactivity, etc.) have received considerable attention [51,52]. hi particular, the properties of water confined in reversed micelles have been widely investigated, since it simulates water hydrating enzymes or encapsulated in biological environments [13,23,53-59]. 

Indeed, the degree of binding of the counterions to the micellar surface, even in the largest aqueous core, is found to be 12% [2,94]. This means that virtually all counterions are confined in a thin shell near the surface (about 4 A), the concentration of ions in this domain is very high, and a nearly ordered bidimensional spherical lattice of charges is formed at the water/surfactant interface of ionic surfactants. 

Solubilization of vinylpyrrolidone, acrylic acid, and A,A -methylene-bis-acrylamide in AOT-reversed micelles allowed the synthesis in situ of a cross-linked polymer with narrow size distribution confined in the micellar domain. These particles displayed high entrapment efficiency of small hydrophilic drugs and have been considered interesting drug delivery systems [239],... 

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