High-Porosity Macroporous Polymers Sythesized from Titania-Particle-Stabilized Medium and High Internal Phase Emulsions

Ikem, Vivian O.; Menner, Angelika; Bismarck, Alexander

doi:10.1021/la9046066

Cited by 164 publications

(161 citation statements)

References 35 publications

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“…The maximum relative density is about 0.13, which is within the established range for light-weight materials 58 . The porosity (void fraction) calculated as ϕ = 1 − ρ f /ρ m 54 is found to be in the range 86.8–92.6% , which is considerably higher than the 40% range reported by conventional foam fabrication methods 7–9 .…”

Section: Resultsmentioning

confidence: 58%

“…The porosity (void fraction) is obtained as ϕ = 1 − ρ f / ρ m , where ρ f and ρ m are the foam and matrix (polymer + CNT) density, respectively 54 . For mechanical characterization, we recorded the response of cylindrical samples ~17 mm in diameter and 13 mm in length to compressive loading using a universal testing machine (Instron Model 4411).…”

Section: Methodsmentioning

confidence: 99%

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An Aqueous-Based Approach for Fabrication of PVDF/MWCNT Porous Composites

Rezvantalab

Ghazi

Ambrusch

et al. 2017

Sci Rep

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In this paper, we demonstrate the fabrication of conductive porous polymers based on foaming of an aqueous dispersion of polymeric particles and multi-walled carbon nanotubes (CNT). By tuning the surface energy of the constituents, we direct their preferential adsorption at the air-liquid (bubble) interface or within the liquid film between the bubbles. Sintering this bi-constituent foam yields solid closed-cell porous structure which can be electrically conductive if CNT are able to form a conductive path. We measure transport (electrical and thermal), mechanical, and morphological properties of such porous structures as a function of CNT loading and the method used for their surface functionalization. For a fixed polymer volume fraction, we demonstrate the limit in which increasing CNT results in decreasing the mechanical strength of the sample due to lack of adequate polymer-CNT bond. Such lightweight conductive porous composites are considered in applications including EMI shielding, electrostatic discharge protection, and electrets.Porous polymer foams are conventionally produced using chemical/physical blowing agents or templating using droplets (emulsion) or solid particles (porogen) 1, 2 . Major limitations of these techniques include lack of control over pore size/size distribution, and applicability to only melt/solution-processable polymers [3][4][5][6] . High viscosity of polymer melts also proves to be challenging for uniform distribution of nanofillers in order to fabricate functional materials. Intractable polymers (i.e. those possessing a high glass transition temperature combined with a relatively low degradation temperature or those having a high molecular weight) cannot be easily melt-processed due to their high melt viscosity. However, such polymers are being used in many practical applications. For instance, Poly(ether ether ketone) (PEEK) is employed for its erosion resistance and excellent mechanical properties at elevated temperatures in pump and valve components as well as in transformer housings, battery holders, and fuel-line brackets. Poly(tetrafluoroethylene) (PTFE) is another example of an intractable polymer known for its non-reactivity and low friction properties in automotive industry. To fabricate porous materials from such polymers, different processes have been developed. They include dispersing of intractable polymer particles in thermally-stable matrices, sintering of uncompressed polymer powders, and inclusion of hollow microspheres typically made of glass, metal, and ceramics inside polymer matrices, i.e. syntactic foams [7][8][9] . However, these processes generally lead to low porosity (<40% air content) which may not be adequate for some applications 10,11 .An alternative approach to fabricate porous structures is to utilize particle-stabilized aqueous foams as precursor 11 . The process is based on the fact that fine solid particles can stabilize liquid-air interfaces resulting in foams that resist bubble coalescence and coarsening. Both melt-processable and intractabl...

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Section: Resultsmentioning

confidence: 58%

Section: Methodsmentioning

confidence: 99%

An Aqueous-Based Approach for Fabrication of PVDF/MWCNT Porous Composites

Rezvantalab

Ghazi

Ambrusch

et al. 2017

Sci Rep

View full text Add to dashboard Cite

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“…Pickering high internal phase emulsions (Pickering-HIPEs) are emulsions stabilized with nanoparticles, which have recently been employed for preparing porous polymer materials (Ikem et al, 2010a, 2011; Kovačič et al, 2012). In Pickering-HIPEs, nanoparticles are present at the oil/water (O/W) interface, evenly packed around the emulsion droplets to form a dense protective layer, so that the size of Pickering emulsion droplets are larger than the dropletes stabilized with surfactants (Xu et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Fabrication of CMC-g-PAM Superporous Polymer Monoliths via Eco-Friendly Pickering-MIPEs for Superior Adsorption of Methyl Violet and Methylene Blue

et al. 2017

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A series of superporous carboxymethylcellulose-graft-poly(acrylamide)/palygorskite (CMC-g-PAM/Pal) polymer monoliths presenting interconnected pore structure and excellent adsorption properties were prepared by one-step free-radical grafting polymerization reaction of CMC and acrylamide (AM) in the oil-in-water (O/W) Pickering-medium internal phase emulsions (Pickering-MIPEs) composed of non-toxic edible oil as a dispersion phase and natural Pal nanorods as stabilizers. The effects of Pal dosage, AM dosage, and co-surfactant Tween-20 (T-20) on the pore structures of the monoliths were studied. It was revealed that the well-defined pores were formed when the dosages of Pal and T-20 are 9–14 and 3%, respectively. The porous monolith can rapidly adsorb 1,585 mg/g of methyl violet (MV) and 1,625 mg/g of methylene blue (MB). After the monolith was regenerated by adsorption-desorption process for five times, the adsorption capacities still reached 92.1% (for MV) and 93.5% (for MB) of the initial maximum adsorption capacities. The adsorption process was fitted with Langmuir adsorption isotherm model and pseudo-second-order adsorption kinetic model very well, which indicate that mono-layer chemical adsorption mainly contribute to the high-capacity adsorption for dyes. The superporous polymer monolith prepared from eco-friendly Pickering-MIPEs shows good adsorption capacity and fast adsorption rate, which is potential adsorbent for the decontamination of dye-containing wastewater.

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“…Using silica particles as functional reinforcement allows to enhance their mechanical properties [11,15,19e21]. Incorporating other particles, such as carbon nanotubes [22,23], titania [24], nanoclay [25] and magnetic particles [26,27], have also been explored. Emulsion templated poly(styrene-co-divinylbenzene)/polyurethane interpenetrated polymer networks were synthesised by L epine et al [28].…”

Section: Introductionmentioning

confidence: 99%