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Selective, ultrathin membrane skins ...

Balachandra, Anagi Manjula.

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Selective, ultrathin membrane skins prepared by deposition of novel polymer films on porous alumina supports.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Selective, ultrathin membrane skins prepared by deposition of novel polymer films on porous alumina supports./
Author:	Balachandra, Anagi Manjula.
Description:	140 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-12, Section: B, page: 6056.
Contained By:	Dissertation Abstracts International64-12B.
Subject:	Chemistry, Analytical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3115933

Selective, ultrathin membrane skins prepared by deposition of novel polymer films on porous alumina supports.
Balachandra, Anagi Manjula.

Selective, ultrathin membrane skins prepared by deposition of novel polymer films on porous alumina supports. - 140 p.

Source: Dissertation Abstracts International, Volume: 64-12, Section: B, page: 6056.

Thesis (Ph.D.)--Michigan State University, 2003.

Membrane-based separations are attractive in industrial processes because of their low energy costs and simple operation. However, low permeabilities often make membrane processes uneconomical. Since flux is inversely proportional to membrane thickness, composite membranes consisting of ultrathin, selective skins on highly permeable supports are required to simultaneously achieve high throughput and high selectivity. However, the synthesis of defect-free skins with thicknesses less than 50 nm is difficult, and thus flux is often limited.Subjects--Topical Terms:

586156
Chemistry, Analytical.

Selective, ultrathin membrane skins prepared by deposition of novel polymer films on porous alumina supports.
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035 $a (UnM)AAI3115933
035 $a AAI3115933
040 $a UnM $c UnM
100 1 $a Balachandra, Anagi Manjula. $3 1952812
245 1 0 $a Selective, ultrathin membrane skins prepared by deposition of novel polymer films on porous alumina supports.
300 $a 140 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-12, Section: B, page: 6056.
500 $a Adviser: Merlin L. Bruening.
502 $a Thesis (Ph.D.)--Michigan State University, 2003.
520 $a Membrane-based separations are attractive in industrial processes because of their low energy costs and simple operation. However, low permeabilities often make membrane processes uneconomical. Since flux is inversely proportional to membrane thickness, composite membranes consisting of ultrathin, selective skins on highly permeable supports are required to simultaneously achieve high throughput and high selectivity. However, the synthesis of defect-free skins with thicknesses less than 50 nm is difficult, and thus flux is often limited.
520 $a Layer-by-layer deposition of oppositely charged polyelectrolytes on porous supports is an attractive method to synthesize ultrathin ion-separation membranes with high flux and high selectivity. The ion-transport selectivity of multilayer polyelectrolyte membranes (MPMs) is primarily due to Donnan exclusion; therefore increase in fixed charge density should yield high selectivity. However, control over charge density in MPMs is difficult because charges on polycations are electrostatically compensated by charges on polyanions, and the net charge in the bulk of these films is small. To overcome this problem, we introduced a templating method to create ion-exchange sites in the bulk of the membrane. This strategy involves alternating deposition of a Cu2+-poly(acrylic acid) complex and poly(allylamine hydrochloride) on a porous alumina support followed by removal of Cu2+ and deprotonation to yield free -COO- ion-exchange sites. Diffusion dialysis studies showed that the Cl-/SO42-. Selectivity of Cu2+-templated membranes is 4-fold higher than that of membranes prepared in the absence of Cu2+. Post-deposition cross-linking of these membranes by heat-induced amide bond formation further increased Cl-/SO42- selectivity to values as high as 600.
520 $a Room-temperature, surface-initiated atom transfer radical polymerization (ATRP) provides another convenient method for formation of ultrathin polymer skins. This process involves attachment of polymerization initiators to a porous alumina support and subsequent polymerization from these initiators. Because ATRP is a controlled polymerization technique, it yields well-defined polymer films with low polydispersity indices (narrow molecular weight distributions). Additionally, this method is attractive because film thickness can be easily controlled by adjusting polymerization time. Gas-permeability data showed that grafted poly(ethylene glycol dimethacrylate) membranes have a CO 2/CH4 selectivity of 20, whereas poly(2-hydroxyethyl methacrylate) (PHEMA) films grown from a surface have negligible selectivity. However, derivatization of PHEMA with pentadecafluorooctanoyl chloride increases the solubility of CO2 in the membrane and results in a CO2/CH4 selectivity of 9.
520 $a Although composite PHEMA membranes have no significant gas-transport selectivity, diffusion dialysis studies with PHEMA membranes showed moderate ion-transport selectivities. Cross-linking of PHEMA membranes by reaction with succinyl chloride greatly enhanced anion-transport selectivities while maintaining reasonable flux. The selectivities of these systems demonstrate that alternating polyelectrolyte deposition and surface-initiated ATRP are indeed capable of forming ultrathin, defect-free membrane skins that can potentially be modified for specific separations.
590 $a School code: 0128.
650 4 $a Chemistry, Analytical. $3 586156
650 4 $a Engineering, Materials Science. $3 1017759
690 $a 0486
690 $a 0794
710 2 0 $a Michigan State University. $3 676168
773 0 $t Dissertation Abstracts International $g 64-12B.
790 1 0 $a Bruening, Merlin L., $e advisor
790 $a 0128
791 $a Ph.D.
792 $a 2003
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3115933