Morphological Effects of Microphase Separation on the Permselectivity for Aqueous Ethanol Solutions of Block and Graft Copolymer Membranes Containing Poly(dimethylsiloxane)

Miyata, Takashi; Obata, Seiji; Uragami, Tadashi

doi:10.1021/ma981949x

Cited by 42 publications

(48 citation statements)

References 33 publications

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“…Other methods have been reported for the synthesis of PDMS-b-PMA by combining anionic with group transfer, 10 atom transfer radical, 11 or free radical polymerization. 12 The above procedures (refs 10-12) lead to materials with high molecular and compositional polydispersity.An alternative and perhaps more versatile approach for the synthesis of block copolymers would be one that employs a linking agent with two different functional groups (heterofunctional linking agent). The reactivity of the two groups should be different toward dissimilar macroanions.…”

mentioning

confidence: 99%

Heterofunctional Linking Agents for the Synthesis of Well-Defined Block Copolymers of Dimethylsiloxane andtert-Butyl Methacrylate or 2-Vinylpyridine

et al. 2001

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The synthesis of block copolymers with a high degree of molecular and compositional homogeneity has facilitated researchers in understanding properties such as morphology, 1,2 dynamics, 3 adsorption, 4,5 and rheology. 6 Furthermore, block copolymers have found useful applications 7 and are potential candidates for many others. 8 The most powerful method for the synthesis of block copolymers is the sequential addition of monomers by anionic polymerization. Unfortunately, there are pairs of polymeric blocks, such as poly(dimethylsiloxane) (PDMS) and polymethacrylates (PMA), that cannot be prepared by this procedure, because the nucleophilicity of the living polymeric blocks does not match the electron affinity of the other monomer. To overcome this problem, Hogen-Esch et al. 9 prepared an -OH endcapped poly(methyl methacrylate) (PMMA) using an R-OH protected initiator. In a second step, the -OH group was transformed, after deprotection, to -OLi group and used to initiate the polymerization of hexamethylcyclotrisiloxane (D 3 ). Although the block copolymers prepared are well-defined, the weak point of this methodology is the instability of the -C-O-Si-group that connects the two blocks. Other methods have been reported for the synthesis of PDMS-b-PMA by combining anionic with group transfer, 10 atom transfer radical, 11 or free radical polymerization. 12 The above procedures (refs 10-12) lead to materials with high molecular and compositional polydispersity.An alternative and perhaps more versatile approach for the synthesis of block copolymers would be one that employs a linking agent with two different functional groups (heterofunctional linking agent). The reactivity of the two groups should be different toward dissimilar macroanions. On the basis of the greater reactivity of the -Si(Me) 2 -Cl than -Ph-CH 2 -Cl group toward silicon-oxygen nucleophiles, 13 we are proposing 2-(chloromethylphenyl)ethyldimethylchlorosilane (CMPDMS) as an efficient heterofunctional linking agent for the synthesis of well-defined block copolymers of PDMS and poly(tert-butyl methacrylate) (PTBMA) or poly(2-vinylpyridine) (P2VP).Experimental Section. a. Equipment and Materials. n-Butyllithium (1.6 M) in hexanes, hexamethylcyclotrisiloxane (D 3 ) (98%), 2-vinylpyridine (98%), tertbutyl methacrylate (99%), (CH 3 ) 3 SiCl (99%), benzene (99%), tetrahydrofuran (THF) (99%), CsI (99.999%), and LiCl (99%) were purchased from Aldrich. CMPDMS (98%), a mixture of para and meta isomers, was purchased from ABCR. Purification of monomers and solvents to the standards required for anionic polymerization has been described in detail elsewhere. 14 s-BuLi was prepared in vacuo from s-butyl chloride and lithium dispersion. Addition and removal of the reagents were performed using break-seals and constrictions. 14 CMPDMS was purified by fractional distillation under high vacuum (10 -6 Torr).Size exclusion chromatography (SEC) experiments were carried out at 25°C in two different setups. In the first a Waters model 510 pump, a Waters model 410 differential ...

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confidence: 99%

Heterofunctional Linking Agents for the Synthesis of Well-Defined Block Copolymers of Dimethylsiloxane andtert-Butyl Methacrylate or 2-Vinylpyridine

et al. 2001

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“…Uragami et al revealed that the continuity of the ODMS phase in the microphase separation strongly influenced the ethanol permselectivity of block and graft copolymers containing ODMS segment, and the percolation transition of the ODMS phase took place at a ODMS content of about 35 mol % (28 wt %) in ODMS-grafted poly-(methyl methacrylate) membrane. 11 The ODMS contents of PAI/ODMS-1 and 3, which were 29.5 and 27.1 wt %, respectively, would cause a boundary morphological effect to exhibit the ethanol permselectivity. On the contrary, PAI/ODMS-1 membrane exhibited unexpectedly the higher selectivity for aqueous acetone permeation than PAI/ODMS-3 membrane.…”

Section: Pervaporation Results Of Pai/odms Graft Copolymer Membranesmentioning

confidence: 99%

Preparation of Oligodimethylsiloxane-grafted Poly(amide–imide) Membrane and Its Separation Properties of Aqueous Organic Liquid Mixtures by Pervaporation

Akimoto

Akiyama

2004

Polym J

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ABSTRACT:In order to develop a durable membrane material for the separation of several organic liquids from their aqueous solutions by using pervaporation technique, oligodimethylsiloxane-grafted aromatic poly(amide-imide) copolymer was prepared by oligomer-polymer reaction. Poly(amide-imide) was reacted with NaH in DMSO to produce polyanion at the N-position of the amide group, followed by the reaction with chloromethylphenyl-terminated oligodimethylsiloxane (ODMS) to obtain the desired graft copolymer. By this oligomer-polymer reaction, ODMS chains with the average degree of polymerization of 13 or 19 were substituted on 19-85 mol % of the amide group, where the degree of substitution was controlled to some extent by changing the mole ratio of NaH and the amide group. The obtained copolymers were soluble in aprotic polar solvents such as DMSO and NMP, and insoluble in the ordinary organic solvents such as alcohol, acetone, THF, benzene, chloroform and dichloromethane. The copolymer membranes were easily prepared by the solvent-casting method from their NMP solutions. The obtained graft copolymer with high ODMS content exhibited the stable and selective permeation of organic solvents, such as alcohol, acetone, THF and dichloromethane, from their dilute aqueous solutions. For example, 0.8 wt % aqueous dichloromethane solution was concentrated to 72.9 wt %, where the separation factor () exceeded 334 with a flux of 0.99 kg m À2 h À1 . [DOI 10.1295/polymj.36.587] KEY WORDS Poly(amide-imide) / Oligodimethylsiloxane / Graft Copolymer / Polymer Reaction / Pervaporation / Separation Membrane / Recently, the pervaporation (PV) technique with a polymer membrane has been focused in much attention for separations of mixtures of several organic liquids and water. In particular, since it is possible to remove organic components from aqueous organic liquid solutions, PV technique is expected to be applied to a removal of organic components from waste fluid. For this purpose, it is more important that the membrane exhibits the organic-permselectivity in the permeation of mixtures of organic liquids and water, and the durability against several organic solvents. A cross-linked polydimethylsiloxane (PDMS) membrane or PDMS-containing copolymer membrane has been known to show a selective permeation of organic liquids in the pervaporation of aqueous organic solutions.1-3 We have also attempted to utilize the properties of a PDMS membrane which exhibited a high permeability of the organic component. For PV materials possessing the mechanical strength and the durability, the syntheses of siloxane-grafted copolymers have been studied, the main chain of which consisted of several aromatic polymers. [4][5][6][7][8][9][10] In our previous work, it was found that polyimide/oligodimethylsiloxane (PI/ODMS) graft copolymer membrane exhibited the high organic permselectivity in aqueous organic liquid solutions, such as acetone, THF chloroform and dichloromethane with a stable PV permeation.10 However, PI/ODMS graft copolymer must be prepar...

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“…14 Recently, glassy materials have gained importance [15][16][17] with respect to which there are reports of using blends of poly(methyl methacrylate) (PMMA) with cellulose acetate, 18 bisphenol chloral polycarbonate, 19 poly(vinylidene fluoride) (PVDF), 20 and poly(dimethylsiloxane) (PDMS) grafted PMMA. 21,22 Separation depends on the properties of the surface and is affected by such physicochemical properties as pore size, wetdiation grafting, 24 surface oxidation, 25 plasma-phase reaction, [26][27][28][29] and copolymerization. Gancarz et al modified the ultrafiltration polysulfone membranes by plasma treatment using CO 2 , 26 acrylic acid, 27 nitrogen, 28 and ammonia 29 and showed an increase in the pore size and wettability.…”

Section: Introductionmentioning

confidence: 99%

Chromium (VI) separation from aqueous solution using anion exchange membrane

Pugazhenthi

Kumar

2005

AIChE Journal

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), which is further reduced to an amine group using hydrazine hydrate to form an anion-exchange membrane (AEM). The membrane thus formed is characterized for its properties such as ionexchange capacity, membrane swelling, contact angle measurements, and membrane morphologies. The results show that the membrane becomes highly hydrophilic on the introduction of a charge and the separation experiments on the chromium (VI) salt solution show that the permeate flux (keeping the same rejection level of 90%) is considerably increased (by 100-fold). The analysis of separation of Cr(VI) from its aqueous solution has been done by solving a two-dimensional (in cylindrical coordinates) space-charge model (SCM). A series solution of the nonlinear Poisson-Boltzmann equation has been generated, which leads to a considerable reduction in the computational

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Morphological Effects of Microphase Separation on the Permselectivity for Aqueous Ethanol Solutions of Block and Graft Copolymer Membranes Containing Poly(dimethylsiloxane)

Cited by 42 publications

References 33 publications

Heterofunctional Linking Agents for the Synthesis of Well-Defined Block Copolymers of Dimethylsiloxane andtert-Butyl Methacrylate or 2-Vinylpyridine

Heterofunctional Linking Agents for the Synthesis of Well-Defined Block Copolymers of Dimethylsiloxane andtert-Butyl Methacrylate or 2-Vinylpyridine

Preparation of Oligodimethylsiloxane-grafted Poly(amide–imide) Membrane and Its Separation Properties of Aqueous Organic Liquid Mixtures by Pervaporation

Chromium (VI) separation from aqueous solution using anion exchange membrane

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