Fabrication and characterization of antistatic epoxy composite with multi-walled carbon nanotube-functionalized melamine foam.

A novel strategy for synthesizing an antistatic epoxy composite was carried out. Pre-embedded antistatic melamine foam was first synthesized and then used to prepare an antistatic epoxy composite. Azidized polyacrylic acid (APAA) was grafted onto multiwalled carbon nanotubes (APAA-MWCNTs) by direct functional modification of the MWCNT sidewalls. Melamine was then covalently bonded to MWCNTs (MA-APAA-MWCNTs). The chemical structure of MA-APAA-MWCNTs was characterized by FT-IR spectroscopy, EDS, TGA, Raman spectroscopy, and TEM. As an antistatic agent, MA-APAA-MWCNTs utilized the functional groups of the surface to participate in the formation of melamine foam by reaction with paraformaldehyde. The surface resistivity was decreased to 3.6 × 108 Ω sq-1 when the loading of MWCNTs was 2.4 kg m-3. The prepared antistatic foam at different compression ratios was immersed in epoxy resin, which was then cured. When the compression ratio reached 40%, the surface resistivity and volume resistivity, respectively, reached 1.05 × 108 Ω sq-1 and 3.5 × 108 Ω cm, thereby achieving an antistatic effect.

A Bioinspired Swimming and Walking Hydrogel Driven by Light-Controlled Local Density.

A hydrogel exhibits a real-time depth-controllable swimming motion via light-mediated modulation of local density to mimic the volume changes found in the bladders of fish. Moreover, other motions, e.g., rolling, somersaulting, and bipedal-like walking, can also be realized by designing or combining gel shapes, and the location of light.

Fabrication of interfacial functionalized porous polymer monolith and its adsorption properties of copper ions.

The interfacial functionalized poly (glycidyl methacrylate) (PGMA) porous monolith was fabricated and applied as a novel porous adsorbent for copper ions (Cu(2+)). PGMA porous material with highly interconnected pore network was prepared by concentrated emulsion polymerization template. Then polyacrylic acid (PAA) was grafted onto the interface of the porous monolith by the reaction between the epoxy group on PGMA and a carboxyl group on PAA. Finally, the porous monolith was interfacial functionalized by rich amount of carboxyl groups and could adsorb copper ions effectively. The chemical structure and porous morphology of the porous monolith were measured by Fourier transform infrared spectroscopy and scanning electron microscopy. Moreover, the effects of pore size distribution, pH value, co-existing ions, contacting time, and initial concentrations of copper ions on the adsorption capacity of the porous adsorbents were studied.

Carbon dioxide adsorbent based on rich amines loaded nano-silica.

An easy strategy to obtain an effective carbon dioxide adsorbent based on rich amines functionalized nano-silica was proposed. Polyacrylic acid (PAA), acted as a multi-functional bridge, was firstly immobilized onto the surface of silica nanoparticles. Each carboxylic acid group was subsequently reacted with an amine group of alkylamines, and plenty of remained amines groups could be coated onto silica nanoparticles. As a result, the rich amines loaded nano-silica was fabricated and applied as CO2 adsorbent. The structures and morphologies of amines modified nano-silica were characterized by FTIR, TGA, TEM, and CHNS elemental analysis. Moreover, the effect of molecular weight of PAA and that of alkylamine on CO2 absorption capacity was discussed. As expected, SiO2-PAA(3000)-PEI(10000) adsorbent possessed remarkably high CO2 uptake of approximately 3.8 mmol/g-adsorbent at 100 KPa CO2, 40°C. Moreover, it was found that the adsorbent exhibited a high CO2 adsorption rate, a good selectivity for CO2-N2 separation, and could be easily regenerated.

Interconnected porous epoxy monoliths prepared by concentrated emulsion templating.

Porous epoxy monoliths were prepared via a step polymerization in a concentrated emulsion stabilized by non-ionic emulsifiers and colloidal silica. A solution in 4-methyl-2-pentanon was used as the continuous phase, which contained glycidyl amino epoxy monomer (GAE), curing agent, and an emulsifier. An aqueous suspension of colloidal silica was used as the dispersed phase of the concentrated emulsion. After the continuous phase was completely polymerized, the dispersed phase was removed and a porous epoxy was obtained. An optimal HLB value of emulsifier for the GAE concentrated emulsion was determined. In addition, the morphology of the porous epoxy was observed by SEM. The effect of the colloidal silica, the emulsifier, the curing of the epoxy, and the volume fraction of the dispersed phase on the morphology of porous epoxy are systematically discussed.

Formation of porous epoxy monolith via concentrated emulsion polymerization.

Step polymerization was introduced into the concentrated emulsion templating method and was illustrated with the preparation of porous epoxy monolith. A solution of diglycidyl ether of bisphenol-A (DGEBA), its curing agent low molecular weight polyamide resin, and surfactant nonyl phenol polyoxyethylene ether in 4-methyl-2-pentanon as a solvent was used as the continuous phase, an aqueous suspension of colloidal silica as the dispersed phase of the concentrated emulsion. After the continuous phase polymerized and the dispersed phase removed, a porous material is obtained. The key point in this work is to find a compromise between the rates of curing and phase separating and thus achieve a kinetic stability of the concentrated emulsion. The effects of loading of colloidal silica, the pre-curing of the epoxy precursors, and the volume fraction of the dispersed phase were systematically investigated.

Preparation of hydrophilic/hydrophobic porous materials.

A novel porous material was designed and prepared in this work. A hydrophobic open-celled porous polystyrene (PS) was first synthesized via a concentrated emulsion polymerization of water in styrene. Subsequently the porous polystyrene was saturated with an aqueous solution of acrylamide (AM) and an initiator, which was subjected to another polymerization and the resulted polyacrylamide (PAM) penetrated in the cells and intercellular pores of the PS matrix. The PAM would change its volume according to the environmental humidity and thus adjusted the permeation of the material. The morphology, pore size distributions, water absorption, and vapor permeation of the materials were investigated.

Hydrophobic Core/Hydrophilic Shell Amphiphilic Particles.

Amphiphilic colloidal particles with hydrophobic cores and hydrophilic shells were prepared via a two-step method. First, polystyrene cores were obtained through the concentrated emulsion polymerization. A mixture of styrene, ethyl benzene, divinyl benzene, azobisisobutyronitrile, and cumene hydroperoxide (CHPO) was partially polymerized at 80 degrees C for 40 min and subsequently used as the dispersed phase of a concentrated emulsion in water. The concentrated emulsion was subjected to complete polymerization at 60 degrees C for 12 h; colloidal particles of crosslinked polystyrene were thus obtained. In the second step, the polystyrene particles were dispersed in water, after which acrylamide, N,N'-methylenebisacrylamide, and ferrous sulfate (FS) were added. The system was heated (typically at 30 degrees C) to conduct the polymerization of the hydrophilic monomers. The CHPO present on the surface of the polystyrene particles and the FS present in the aqueous phase (both together constitute a redox initiator) ensured that the initiation occurred mostly on the surface of the particles and that the hydrophilic polymer obtained formed a shell encapsulating the particles. Under proper conditions, a porous outer shell could be generated, making the hydrophobic core accessible to the outside medium. Copyright 2001 Academic Press.