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

The gas sensors fabricated by using conducting polymers such as polyaniline (PAni), polypyrrole (PPy) and poly (3,4-ethylenedioxythiophene) (PEDOT) as the active layers have been reviewed. This review discusses the sensing mechanism and configurations of the sensors. The factors that affect the performances of the gas sensors are also addressed. The disadvantages of the sensors and a brief prospect in this research field are discussed at the end of the review.

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Gas Sensors Based on Conducting Polymers

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

Reversible crystallization and the rigid-amorphous phase in semicrystalline macromolecules

PolyHIPEs: Recent advances in emulsion-templated porous polymers

PolyHIPE: IPNs, hybrids, nanoscale porosity, silica monoliths and ICP-based sensors

Organic-inorganic networks in foams from high internal phase emulsion polymerizations

The synthesis and characterization of novel polymerized high internal-phase emulsions (polyHIPE) materials are described. Homogeneous, highly porous, low-density, open-cell crosslinked copolymers were prepared by polymerizing the continuous phase of HIPE containing styrene and varying amounts of 2-ethylhexyl methacrylate. The glass transition temperatures (Tgs) of the homopolymers were similar to the literature values, but the copolymer Tgs were lower than expected. These results indicate that the copolymer composition is richer in 2-ethylhexyl methacrylate than the feed composition. The homopolymer moduli, calculated from the foam moduli, were similar to the literature values. The influence of composition and surface treatment on the water absorbed by the foams was investigated. For example, washing a polyHIPE based on poly(ethylhexyl acrylate) in water at 70°C increased water absorption because of the removal of the residual salt. Adding a fluorinated comonomer to the HIPE reduced hydrophilicity and, thus, water absorption. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2018–2027, 2002; DOI 10.1002/app.10555

Polymerized high internal-phase emulsions: Properties and interaction with water

High internal phase emulsion (HIPE) copolymer and interpenetrating network foams were prepared from 2-ethylhexyl acrylate (EHA), styrene (S) and divinylbenzene (DVB) using a unique process. The morphologies, thermal properties and dynamic and static mechanical properties of these foams were investigated. The glass transition temperatures and damping properties of the EHA/S copolymer foams vary with its composition. IPN foams with very broad tan 5 peaks were obtained. The damping properties of IPN foams were tailored through changing copolymer composition and monomer composition. The IPN foams based on a copolymer foam and styrene had a broader tan δ peak, a higher glass transition temperature and a higher modulus than tne copolymer foams of similar overall styrene contents. It is therefore possible to prepare novel damping foams based on polyHIPE foams through the synthesis of interpenetrating polymer networks.

Huiwen Tai

Papers

PolyHIPE: IPNs, hybrids, nanoscale porosity, silica monoliths and ICP-based sensors

Organic-inorganic networks in foams from high internal phase emulsion polymerizations

Polymerized high internal-phase emulsions: Properties and interaction with water

High internal phase emulsion foams: Copolymers and interpenetrating polymer networks