Control of water permeation by pH and ionic strength through a porous membrane having poly(carboxylic acid) surface-grafted

Ito, Yoshihiro; Inaba, Masahiro; Chung, Dong June; Imanishi, Yukio

doi:10.1021/ma00052a037

Cited by 144 publications

(111 citation statements)

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“…At pH 5.5 the poly(acrylic acid) decreased the porosity of the silica particles by 31% while at pH 1.5 by 26%. These observations are in agreement with experiments by Ito et al [11] who reported that poly(-acrylic acid)-grafted porous polycarbonate membranes showed higher water permeability at lower pH than at higher pH.…”

Section: Resultssupporting

confidence: 93%

Modification of porous silica particles with poly(acrylic acid)

Suzuki

Siddiqui

Chappell

et al. 2000

Polym. Adv. Technol.

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High yields of nanocrystals at ambient temperaturehave been attained for several inorganic salts such as ZnS and CuO. The authors report one‐step, solid‐state reactions between easily obtained starting materials such as CuCl2·2H2O and NaOH to give nanoparticles with narrow size distribution. The process is carried out in air and requires no complex apparatus, reagents, or techniques and thus it shows potential for mass production of nanocrystals. All of the reactions investigated involve hydrated salts, and the role of the water in the reaction mechanism is discussed.

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Section: Resultssupporting

confidence: 93%

Modification of porous silica particles with poly(acrylic acid)

Suzuki

Siddiqui

Chappell

et al. 2000

Polym. Adv. Technol.

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“…Gating membranes have been made using stimuli-responsive hydrogels, which exhibit reversible phase changes in response to temperature, pH, or electric charge. 1,[17][18][19] Some disadvantages are associated with applying hydrogels though. For example, hydrogel membranes have low mechanical stability and low molecular diffusivity.…”

Section: 1516mentioning

confidence: 99%

Reversible gating of ion transport through DNA-functionalized carbon nanotube membranes

et al. 2017

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Carbon nanotubes (CNTs) can be used to create unique fluidic systems for studying ion transport in nanochannels due to their well-defined geometry, atomically smooth and chemically inert surface, and similarity to transmembrane protein pores. Here, we report the reversible molecular gating of ion transport across DNA-functionalized CNT membranes. The diffusive transport rates of ferricyanide ions through membranes, each with an array of aligned transmembrane CNT channels, were monitored.Single-stranded DNA (T15) gate molecules were covalently linked to CNT channel entrances, and reversible opening and closing of CNT channels were achieved by the addition and removal of complementary DNAs (A15) with a remarkable open/close flux ratio of >1000, which is substantially higher than the protein-gated CNT systems reported previously. Furthermore, at least two-orders of magnitude difference in ion fluxes was observed when single base-pair mismatched DNAs were used in place of the complementary DNAs. Comprehensive theoretical analysis is also presented. The experimental results can be explained by steric hindrance, ion partitioning, and electrostatic repulsion at the CNT entrances, as well as the thermodynamics of DNA binding.Protein channels are fascinating structures, which can selectively and efficiently transport essential chemicals through cell membranes. The fabrication of synthetic membranes with nanopores that mimic biological transmembrane protein channels have numerous applications, ranging from drug delivery, water purication, and molecular sieving, to DNA sensing.1-4 These membranes possess selective gate chemistry at the pore entrance, a mechanism for fast hydrodynamic ow, and a mechanism to stimulate the channel.5 Several different approaches were developed to create biomimetic membranes. Previous studies have investigated the use of porous alumina or track-etched polycarbonate substrates with well-ordered nanoporous structures and selective chemistry.3,4,6-8 However, these works did not show the capability to create an efficient chemical layer to act as a gatekeeper over the pores and no enhancement to hydrodynamic ow was observed either. Recently, carbon nanotubes (CNTs) have been investigated as biomimetic uidic channels due to their fast hydrodynamic velocity proles, highly uniform and tunable pore diameters, and potential gating capabilities.9-14 Early molecular dynamics (MD) simulations predicted strong hydrogen bonding of water in hydrophobic CNTs, resulting in a faster hydrodynamic ow rate than that expected for conventional porous platforms 9 and on the same order as water through Aquaporin-1. MD simulations and experiments have shown that the increased hydrodynamic ow velocities through CNTs can be attributed to the atomic smoothness of the graphitic surface displaying near-perfect slip properties. 9,11 In other studies, a fast ow rate of molecules was also predicted based on the near frictionless nature of the CNT walls. 11,15,16

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“…[13] Polymer systems that show a well-defined change in volume are of special interest due to their applicability in switching transport pathways in the nano-or micro-scale. ''Smart'' porous membranes are ''nano systems'' which had already been studied by various research groups; [14][15][16][17][18][19][20] ''grafting-from'' using hydrogen abstraction photoinitiators has also been used with the intention to prepare functionalized pore surfaces. [16,18,19] On the other hand, investigations towards ''smart'' polymer valves or other modules for micro systems (''lab-on-achip'') have started only recently.…”

Section: Introductionmentioning

confidence: 99%

Photoreactive Functionalization of Poly(ethylene terephthalate) Track‐Etched Pore Surfaces with “Smart” Polymer Systems

Geismann

Ulbricht

2005

Macro Chemistry & Physics

116

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Summary: Poly(ethylene terephthalate) (PET) track‐etched membranes with a pore diameter of ca. 700 nm, optionally surface‐functionalized to create a “carboxyl” or “amino” surface, were used for heterogeneous graft copolymerizations. Grafted poly(acrylic acid) acted as a pH responsive, “smart” polymer. To evaluate the surface‐specific initiation of graft copolymerizations unmodified and primary functionalized membranes were systematically combined with three differently charged benzophenone derivatives as photoinitiators, which were adsorbed on the PET surface prior to the reaction. The functionalized membranes thus obtained were characterized for chemical structure and permeability as a function of pH. The pore structure with a narrow size distribution and the resulting high sensitivity of the membrane permeability to the grafting functionalizations made the track‐etched PET membranes a very useful tool for analyzing structure and function of responsive grafted polymer layers. The primary functionalization of the base polymer with a molecular layer of a multifunctional alkylamine (“amino” surface) enhanced the efficiency of the subsequent graft copolymerization via photoinitiated hydrogen abstraction considerably because a high density of well accessible reactive groups had been introduced. The preadsorption of the photoinitiator on the base polymer surface was significantly improved by ionic interactions between the respective functional groups of the surface and the photoinitiator. Such a photoinitiator preadsorption, especially when combined with a reactive layer from the primary functionalization, enabled a very efficient and surface selective functionalization because a better control of grafting density and a reduction of photoinitiated side reactions along with a more efficient use of the photoinitiator were possible.Water permeabilities (pH 2 and pH 7) of unmodified and functionalized PET membranes for identification of optimal synthesis and evaluation conditions.magnified imageWater permeabilities (pH 2 and pH 7) of unmodified and functionalized PET membranes for identification of optimal synthesis and evaluation conditions.

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Control of water permeation by pH and ionic strength through a porous membrane having poly(carboxylic acid) surface-grafted

Cited by 144 publications

References 2 publications

Modification of porous silica particles with poly(acrylic acid)

Modification of porous silica particles with poly(acrylic acid)

Reversible gating of ion transport through DNA-functionalized carbon nanotube membranes

Photoreactive Functionalization of Poly(ethylene terephthalate) Track‐Etched Pore Surfaces with “Smart” Polymer Systems

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