Mosaic Membranes

Alternatively, the film is placed between two perforated lead plates and grafted with monomer M by the mutual method. After grafting, the film is now placed between the two perforated lead plates taking precautions that only the ungrafted portions of the grafted film are exposed to gamma radiations in the presence of monomer M2. Schematically, the preparation of the mosaic membrane is shown in Fig. 2. 

Figure 2 Preparation of mosaic membrane (a) film grafted with monomer Mi and (b) Mi grafted film further grafted with monomer M2.

HV Alginate 2% Spermine/1% Poly-methylene-co-guanidine T Smooth, Mosaic Membrane (Polymer Incompatibility ) 7/7... 

Membranes classified under (c) in the introductory section are of considerable importance. Most natural membranes are macroscopically non-homogeneous. In artificial membranes non-homogeneity may be introduced either deliberately (laminates, asymmetric membranes) or spuriously (e.g. skin layers on films made by extrusion). Variation of S and Dx across the membrane, i.e. in the X direction, is of particular interest non-homogeneity along the plane of the membrane is important in certain special cases, e.g. charged mosaic membranes, which are not of immediate interest here. Also asymmetric membranes prepared for the sole purpose of producing an ultrathin active layer to maximize permeation flux are outside the scope of the present discussion. 

Figure 13.5 Charge mosaic membranes, consisting of finely dispersed domains containing fixed negatively and fixed positively charged groups, are salt permeable [15]...

Figure 13.7 Piezodialysis of 0.02 M potassium chloride solution with block copolymer charge mosaic membranes [14]. Enrichment is calculated using the expression ...

C.R. Gardner, J.N. Weinstein and S.R. Caplan, Transport Properties of Charge-mosaic Membranes, Desalination 12, 19 (1973). 

Polymerization of the D-glucan chains occurs by way of a multi-subunit, enzyme complex embedded in the plasma membrane an almost simultaneous association, by means of hydrogen bonds, of the newly formed chains results in formation of partially crystalline microfibrils. This mechanism of polymerization and crystallization results in the creation of microfibrils whose chains are oriented parallel (cellulose I). In A. xylinum, the complex is apparently immobile, but, in cells in which cellulose is deposited as a cell-wall constituent, it seems probable that the force generated by polymerization of the relatively rigid microfibrils propels the complex through the fluid-mosaic membrane. The direction of motion may be guided through the influence of microtubules. 

Donnan dialysis successfully involves mosaic membranes which are an important part of piezodialysis. Their basic advantage is the close juxtapoation of anion- and cation-exchange resins in the same membrane. It is a pity that research on piezodialysis, a desalination process with great promise and hopes, has been abandoned. However, one may expect work on it will be reassumed as soon as some difficulties originated from the deficiency of mosaic membranes, as well as some engineering problems, are overcome. 

R. Kiyono, Y. Asai, Y. Yamada, A. Kishihara and M. Tasaka, Anomalous water transport across cation-exchange membranes under an osmotic pressure difference in mixed aqueous solutions of hydrochloric acid and alkali metallic halide, Seni Gakkaishi, 2000, 56, 298-301 M. Tasaka, T. Okano and T. Fujimoto, Mass transport through charge-mosaic membranes, J. Membrane Sci., 1984,19, 273-288. 

G.H. Ma and T. Fukutomi, Preparation and chemical fixation of poly(4-vinylpyridine) microgel film with ordered structure, Macromolecules, 1992, 25, 1870-1875 M. Takizawa, Y. Sugimoto, S. Doi, Y. Isono, M. Nakamura, S. Horiguchi and T. Fukutomi, Fabrication of novel charge-mosaic membranes using microsphere and their application, Curr. Trends Polym. Sci., 2001, 6, 59-66. 

L.K. Platt and A. Schindler, Ionic membranes for water desalination. I. Charge mosaic membranes from blends of random copolymers, Angew. Makromol. Chem., 1971, 19, 135. 

Y. Miyaki, H. Nagamatsu, M. Iwata, K. Ohkoshi, K. Se and T. Fujimoto, Artificial membranes from multiblock copolymers. 3. Preparation and characterization of charge-mosaic membranes, Macromolecules, 1984, 17, 2231-2236 H. Itou, M. Toda, K. Ohkoshi, M. Iwata, T. Fujimoto, Y. Miyaki and T. Kataoka, Artificial membranes from multiblock copolymers. 6. Water and salt transport through a charge-mosaic membrane. Ind. Eng. Chem. Chem. Res., 1988, 27, 983-987 Y. Miyamoto, Fabrication of charge-mosaic membranes and their performance, Maku (Membrane), 1991, 16, 233-238. 

L. Liang and S. Ying, Charge-mosaic membrane from gamma-irradiated poly(styrene-butadiene-4-vinylpyridine) triblock copolymer, J. Polym. Sci., Polym. Phys., 1993, 31, 1075-1081. 

T. Fukutomi, M. Takizawa, M. Nakamura, Charge mosaic membrane and production process thereof, USP 5,543,045, Aug, 1996 A. Yamauchi, J. Tateyama, B. Itoh,... 

M. Takizawa, Y. Sugito and S. Doi, Charged mosaic membrane prepared from microsphere gel and its characterization, J. Membr. Sci., 2000, 173, 275-280. 

K. Sato, T. Sakairi, T. Yonemoto and T. Tadaki, The desalination of a mixed solution of an amino acid and an inorganic salt by means of electrodialysis with charge-mosaic membranes, J. Membr. Sci., 1995,100, 209-216. 

T. Fukuda and A. Yamauchi, Electrolyte transport through charged mosaic membranes under the presence of non-electrolytes, Kaisui Gakkaishi (Bull. Soc. Sea Water Sci.), 2002, 36, 41-46. 

T. Fukuda and A. Yamauchi, Transport behavior of amino acid across charged mosaic membrane, Bull. Chem. Soc. Jpn., 2000, 73, 2729-2732. 

In 1976, Chapiro et al. [19] reported on the grafting of so-called mosaic membranes. In two successive grafting steps, they produced well-localized domains of acrylic acid (AA) and 4-vinylpyridine (4VP)... 

---