Dingcai Wu,*,† Fei Xu,† Bin Sun,† Ruowen Fu,† Hongkun He,‡ and Krzysztof Matyjaszewski*,‡ †Materials Science Institute, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, People's Republic of China ‡Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States

Design and Preparation of Porous Polymers

Emulsions stabilized with solid nanoparticles: Pickering emulsions

Owing to their immense potential in energy conversion and storage, catalysis, photocatalysis, adsorption, separation and life science applications, significant interest has been devoted to the design and synthesis of hierarchically porous materials. The hierarchy of materials on porosity, structural, morphological, and component levels is key for high performance in all kinds of applications. Synthesis and applications of hierarchically structured porous materials have become a rapidly evolving field of current interest. A large series of synthesis methods have been developed. This review addresses recent advances made in studies of this topic. After identifying the advantages and problems of natural hierarchically porous materials, synthetic hierarchically porous materials are presented. The synthesis strategies used to prepare hierarchically porous materials are first introduced and the features of synthesis and the resulting structures are presented using a series of examples. These involve templating methods (surfactant templating, nanocasting, macroporous polymer templating, colloidal crystal templating and bioinspired process, i.e. biotemplating), conventional techniques (supercritical fluids, emulsion, freeze-drying, breath figures, selective leaching, phase separation, zeolitization process, and replication) and basic methods (sol–gel controlling and post-treatment), as well as self-formation phenomenon of porous hierarchy. A series of detailed examples are given to show methods for the synthesis of hierarchically porous structures with various chemical compositions (dual porosities: micro–micropores, micro–mesopores, micro–macropores, meso–mesopores, meso–macropores, multiple porosities: micro–meso–macropores and meso–meso–macropores). We hope that this review will be helpful for those entering the field and also for those in the field who want quick access to helpful reference information about the synthesis of new hierarchically porous materials and methods to control their structure and morphology.

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Hierarchically porous materials: synthesis strategies and structure design

The introduction of carbon nanotubes (CNTs) into conventional fibre-reinforced polymer composites creates a hierarchical reinforcement structure and can significantly improve composite performance. This paper reviews the progress to date towards the creation of fibre reinforced (hierarchical) nanocomposites and assesses the potential for a new generation of advanced multifunctional materials. Two alternative strategies for forming CNT-based hierarchical composites are contrasted, the dispersion of CNTs into the composite matrix and their direct attachment onto the primary fibre surface. The implications of each approach for composite processing and performance are discussed, along with a summary of the measured improvements in the mechanical, electrical and thermal properties of the resulting hierarchical composites.

Carbon nanotube-based hierarchical composites: a review

We studied oil in water Pickering emulsions stabilized by cellulose nanocrystals obtained by hydrochloric acid hydrolysis of bacterial cellulose. The resulting solid particles, called bacterial cellulose nanocrystals (BCNs), present an elongated shape and low surface charge density, forming a colloidal suspension in water. The BCNs produced proved to stabilize the hexadecane/water interface, promoting monodispersed oil in water droplets around 4 μm in diameter stable for several months. We characterized the emulsion and visualized the particles at the surface of the droplets by scanning electron microscopy (SEM) and calculated the droplet coverage by varying the BCN concentration in the aqueous phase. A 60% coverage limit has been defined, above which very stable, deformable droplets are obtained. The high stability of the more covered droplets was attributed to the particle irreversible adsorption associated with the formation of a 2D network. Due to the sustainability and low environmental impact of cellulose, the BCN based emulsions open opportunities for the development of environmentally friendly new materials.

New Pickering emulsions stabilized by bacterial cellulose nanocrystals

Liquid Screen: A Novel Method To Produce an In-Situ Gravel Pack

This invention relates to subterranean treatment operations. More particularly, this invention provides methods that may be useful in providing void-free barriers between a subterranean formation and a portion of a well bore. A nonlimiting example of a method is a method of degrading a filter cake in a subterranean formation. Another nonlimiting example of a method is a method of producing hydrocarbons from a subterranean formation.

Methods for Forming a Permeable and Stable Mass in a Subterranean Formation

Abstract Emulsion templates containing monomers in both emulsion phases were used to manufacture polystyrene-co-divinylbenzene based polymerized high internal phase emulsions (polyHIPEs) which have been reinforced by poly(methacrylic acid) (polyMAA) and poly(dimethyl aminoethyl methacrylate) (polyDMAEMA). The morphology of the hydrogel-filled polyHIPEs is affected by the hydrogels synthesized in the aqueous emulsion phase. The pore structure of polyMAA-filled polyHIPEs is highly interconnected indicating the formation of a methacrylic acid-co-styrene copolymer at the oil/water interface of the emulsion templates during synthesis. However, polyDMAEMA-filled polyHIPEs are predominately closed celled and the pore walls are covered by grafted hydrogel. The ability of the hydrogel-filled polyHIPEs to absorb water decreased with increasing crosslinking density of the hydrogels. The dry hydrogel reinforced the polyHIPE scaffolds possessed higher elastic moduli and crush strengths than the control polyHIPEs. The reinforcing ability of the dry hydrogels was further enhanced by increasing their degree of crosslinking. However, the reinforcement could be “switched off” simply by hydrating the hydrogels. The switchable mechanical properties of the hydrogel-filled polyHIPEs could potentially be utilized in smart humidity sensor technology.

Emulsion-templated macroporous polymer/polymer composites with switchable stiffness

• Continuous L-L extraction in polyHIPE microextractor and gravity-based settler. • Extractor made by combining hydrophilic and hydrophobic macroporous polymers. • Improved mass transfer efficiency compared to commercial static mixer. • 98% extraction efficiency of 4-aminoacetophenone from a solvent mixture. Continuous liquid-liquid extraction and separation of 4-aminoacetophenone, a product of the hydrogenation of 4-nitroacetophenone, was performed within emulsion templated macroporous polymer (polyHIPE) extraction units combined with a miniaturized gravity-based settler. PolyHIPEs with interconnected and tailorable macroporous structures are effective micromixers allowing to mix fluids in both axial and radial directions. We fabricated extraction units by combining hydrophilic and hydrophobic polyHIPEs, which improved the extraction efficiency by inverting the liquid/liquid dispersion type from oil/water to water/oil (or vice versa) during the extraction. The dispersion type is governed by the wettability of the porous medium. The extraction efficiency of our combined polyHIPE micromixer reached 98%, while that of control experiments performed using a blank tube or commercial Kenics® static mixer was 78%. The overall volumetric mass transfer coefficient k L a in polyHIPE micromixer-settlers was significantly higher 0.011 s −1 reaching interfacial areas a of 17900 m 2 /m 3 , much larger compared to a blank tube ( k L a = 0.0035 s −1 and a = 5700 m 2 /m 3 ) and static mixer ( k L a = 0.0041 s −1 and a = 6800 m 2 /m 3 ). PolyHIPE micromixer-settlers could be potentially useful to intensify continuous L-L extractions. 

Liquid-liquid extraction using combined hydrophilic-hydrophobic emulsion templated macroporous polymer micromixer-settlers

The present invention relates to methods and compositions useful for isolating a portion of a wellbore. In one embodiment, a method includes preparing a sealant composition contaimng two phases. The sealant composition is placed into the wellbore where one phase sets upon subjecting the sealant composition to a thermal source followed by the setting of the other phase.

Angelika Menner

Papers

Liquid Screen: A Novel Method To Produce an In-Situ Gravel Pack

Methods for Forming a Permeable and Stable Mass in a Subterranean Formation

Emulsion-templated macroporous polymer/polymer composites with switchable stiffness

Liquid-liquid extraction using combined hydrophilic-hydrophobic emulsion templated macroporous polymer micromixer-settlers

Hybrid cement set-on-command compositions and methods of use