Syntheses of complex mesoporous silicas using mixtures of nonionic block copolymer surfactants: Understanding formation of different structures using solubility parameters

Chen, Lan; Xu, Jiaqiang; Zhang, Wenhua; Holmes, Justin D.; Morris, Michael A.

doi:10.1016/j.jcis.2010.09.043

Cited by 23 publications

(20 citation statements)

References 49 publications

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“…44 The solubility parameter theory is a valuable tool and often used to estimate the dissolving ability or aggregation state of copolymers in various solvents. 45,46 Herein, the solubility parameters (d) of PEGMA, PTFOA blocks, and DMF were about 14.5, 10.8, and 12.1 (cal 1/2 cm 22/3 ), respectively. Due to the significantly different affinities toward the solvent of P(PEG-b-TFOA) constituent blocks, the amphiphilic block copolymers would be inclined to show microphase separation structures, resulting in plenty of aggregation clusters and slight dissolved single chain configuration in solution (see Figure 5a).…”

Section: Surface Chemical Composition and Surface Segregation Mechanismmentioning

confidence: 90%

Amphiphilic poly(ether sulfone) membranes for oil/water separation: Effect of sequence structure of the modifier

et al. 2016

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Oil‐contaminated wastewater threatens our environment and health thus novel membrane materials with low or nonfouling properties are an immediate need for oily wastewater treatment in a cost‐effective and environmentally friendly manner. In this study, three types of amphiphilic random, gradient, and block copolymers with similar molecular weights and chemical compositions, based on poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctyl acrylate (TFOA), were synthesized by the reversible addition‐fragmentation chain transfer (RAFT) method. The amphiphilic Poly(ether sulfone) membranes were then fabricated by blending with these copolymers via a facile coupled process of nonsolvent induced phase separation and surface segregation. Accompanying the phase inversion process of polymer matrix, the hydrophilic and hydrophobic segments in the amphiphilic modifiers would migrate and immobilize onto the membrane surfaces. This surface segregation process leaded to a chemical heterogeneous membrane surface comprising both hydrophilic PEGMA and low surface energy PTFOA brushes, which was confirmed by X‐ray photoelectron spectroscopy (XPS) and surface wettability analyses. Oil‐in‐water emulsion filtration test of the membranes displayed a lower permeate flux decline and a higher flux recovery (as high as 99.8%), establishing their considerably elevated antifouling properties. Additionally, cyclic oil/water separation and long‐term underwater immersion tests demonstrated that the as‐prepared membranes modified by these amphiphilic additives possessed excellent antifouling stabilities. © 2016 American Institute of Chemical Engineers AIChE J, 63: 739–750, 2017

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Section: Surface Chemical Composition and Surface Segregation Mechanismmentioning

confidence: 90%

Amphiphilic poly(ether sulfone) membranes for oil/water separation: Effect of sequence structure of the modifier

et al. 2016

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“…There are several variables of forming ordered mesoporous structure such as reactant concentration, synthesis temperature, pH of solution, and the nature of surfactant. However, the effects of mixed surfactants on ordered mesoporous silica are hardly known because there have been several researches related with single surfactant, but there have been only few researches with mixed surfactants [10][11][12][13][14][15][16][17]. Lan Chen et al made their studies on the mixture of various surfactants and synthesized the bimodal structure in P123-P65-25R4 system.…”

Section: Introductionmentioning

confidence: 99%

Pore Structure Control of Ordered Mesoporous Silica Film Using Mixed Surfactants

Yoon

et al. 2011

Journal of Nanomaterials

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Materials with nanosized and well-arranged pores have been researched actively in order to be applied to new technology fields. Especially, mesoporous material containing various pore structures is expected to have different pore structure. To form a mixed pore structure, ordered mesoporous silica films were prepared with a mixture of surfactant; Brij-76 and P-123 block copolymer. In mixed surfactant system, mixed pore structure was observed in the region of P-123/(Brij-76 + P-123) with about 50.0 wt.% while a single pore structure was observed in regions which have large difference in ratio between Brij-76 and P-123 through the X-ray diffraction analysis. Regardless of surfactant ratio, porosity was retained almost the same. It is expected that ordered mesoporous silica film with mixed pore structure can be one of the new materials which has distinctive properties.

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“…Seeing that Pluronic surfactants can form mixed micelles, 39-41 binary blends of Pluronic surfactants have been successfully used to vary pore size in a range between that obtained with pure mesophases of either surfactant (keeping the total mass of template constant), [42][43][44] and that the pore size of mesoporous carbon templated by F127 can be increased by the addition of Brij non-ionic surfactants, 45 we 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 7 hypothesized that large-pore mesoporous silica films could be synthesized using EISA with the template F127 and the addition of a chemically similar secondary Pluronic polymer that functions as a SA, without inducing phase separation. Our results confirm this hypothesis, with a ca.…”

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confidence: 99%

Enlarged Pore Size in Mesoporous Silica Films Templated by Pluronic F127: Use of Poloxamer Mixtures and Increased Template/SiO₂ Ratios in Materials Synthesized by Evaporation-Induced Self-Assembly

et al. 2014

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Although evaporation-induced self-assembly (EISA) has proven to be a convenient method for synthesizing nanoporous silica films (and particles), accessing material structures with pore sizes larger than ca. 10 nm remains experimentally inconvenient. The use of pore swelling agents (SAs), commonly used during the hydrothermal synthesis of mesoporous silicas, results in little or no pore size expansion due to evaporation or phase separation. Moreover, diblock copolymer templates can yield large pores, but are quite expensive and generally require the addition of strong organic cosolvents. Here, we hypothesized that pores templated by the Pluronic triblock polymer F127 could be successfully enlarged, without phase separation, by using a chemically similar, non-volatile, secondary Pluronic (P103) as the SA. We find pore size increased up to 15 nm for a spherical pore morphology, with a phase transition to a multilamellar vesicle (MLV) based nanostructure occurring as the P103/F127 ratio is further increased. This MLV phase produces even larger pore sizes due to collapse of concentric silica shells upon template removal.Remarkably, F127 alone exhibits expansion of pore size (up to ca. 16 nm) as the template/silica ratio is increased. We find appearance of the MLV phase is due to geometric packing considerations, with expansion of F127 micelle size a result of favorable intermolecular interactions driven by the large polyethylene oxide content of F127. Other Pluronic polymers with this feature also exhibit variable pore size based on the template/silica ratio, enabling the synthesis of mesoporous films with 3D pore connectivity and truly variable pore size of ca. 4.5 to almost 20 nm. Particles and films of mesoporous silica (MPS) templated by condensation of solution-phase sol-gel precursors around self-assembled surfactant mesophases, either through solution processing 1,2 or evaporation-induced self-assembly (EISA), 3,4 have become an important class of nanostructured materials, with potential applications ranging from catalytic supports 5 and adsorbents for environmental remediation 6 to drug delivery 7,8 and nanoporous molecular separation membranes. 9,10 A prominent feature of these materials is the ease in which pore size can be engineered through the identity of commonly available off-the-shelf surfactant templates, starting at ca. 2 nm, 11,12 though the use of alkylammonium surfactants such as cetyltrimetylammonium bromide (CTAB), 1 up to approximately 10 nm with amphiphilic block co-polymer templates such as the poloxamer series of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblocks (PEO-PPO-PEO, exemplified by the SBA series of mesoporous silicas). 13-15 However, a need for greater pore size (pushed in part by the use of MPS to deliver large biomolecular cargos such as DNA or functional proteins) 16-19 has driven research into methods for expanding the upper limit of this range. One strategy that has been successful in synthesizing porous materials with pore sizes of even greater than 40...

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Syntheses of complex mesoporous silicas using mixtures of nonionic block copolymer surfactants: Understanding formation of different structures using solubility parameters

Cited by 23 publications

References 49 publications

Amphiphilic poly(ether sulfone) membranes for oil/water separation: Effect of sequence structure of the modifier

Amphiphilic poly(ether sulfone) membranes for oil/water separation: Effect of sequence structure of the modifier

Pore Structure Control of Ordered Mesoporous Silica Film Using Mixed Surfactants

Enlarged Pore Size in Mesoporous Silica Films Templated by Pluronic F127: Use of Poloxamer Mixtures and Increased Template/SiO₂ Ratios in Materials Synthesized by Evaporation-Induced Self-Assembly

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Syntheses of complex mesoporous silicas using mixtures of nonionic block copolymer surfactants: Understanding formation of different structures using solubility parameters

Cited by 23 publications

References 49 publications

Amphiphilic poly(ether sulfone) membranes for oil/water separation: Effect of sequence structure of the modifier

Amphiphilic poly(ether sulfone) membranes for oil/water separation: Effect of sequence structure of the modifier

Pore Structure Control of Ordered Mesoporous Silica Film Using Mixed Surfactants

Enlarged Pore Size in Mesoporous Silica Films Templated by Pluronic F127: Use of Poloxamer Mixtures and Increased Template/SiO2 Ratios in Materials Synthesized by Evaporation-Induced Self-Assembly

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Enlarged Pore Size in Mesoporous Silica Films Templated by Pluronic F127: Use of Poloxamer Mixtures and Increased Template/SiO₂ Ratios in Materials Synthesized by Evaporation-Induced Self-Assembly