Small but strong: A review of the mechanical properties of carbon nanotube–polymer composites

Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

Thermal conductivity of carbon nanotubes and their polymer nanocomposites: A review

Polymer/carbon nanotube (CNT) composites are expected to have good processability characteristics of the polymer and excellent functional properties of the CNTs. The critical challenge, however, is how to enhance dispersion and alignment of CNTs in the matrix. Here, we review recent progress and advances that have been made on: (a) dispersion of CNTs in a polymer matrix, including optimum blending, in situ polymerization and chemical functionalization; and (b) alignment of CNTs in the matrix enhanced by ex situ techniques, force and magnetic fields, electrospinning and liquid crystalline phase-induced methods. In addition, discussions on mechanical, thermal, electrical, electrochemical, optical and super-hydrophobic properties; and applications of polymer/CNT composites are included. Enhanced dispersion and alignment of CNTs in the polymer matrix will promote and extend the applications and developments of polymer/CNT nanocomposites.

Dispersion and alignment of carbon nanotubes in polymer matrix: A review

https://tore.tuhh.de/bitstream/11420/394/1/Article_5._free.pdf

A review and analysis of electrical percolation in carbon nanotube polymer composites

Mechanical properties and electrical conductivity of carbon-nanotube filled polyamide-6 and its blends with acrylonitrile/butadiene/styrene

The chemical metallization of aqueous bentonite dispersions afforded stable aqueous hybrid nanoparticle dispersions containing simultaneously dispersed sodium bentonite nanoplatelets together with bentonite supported silver, palladium, or copper nanoparticles with average metal nanoparticle diameters varying between 14 and 40 nm. Such aqueous bentonite/metal hybrid nanoparticle dispersions were blended with cationic PMMA latex to produce PMMA hybrid nanocomposites containing exfoliated polymer-grafted organoclay together with bentonite supported metal nanoparticles. This dispersion blend formation was investigated with respect to the role of nanostructure formation and mechanical properties. Palladium/bentonite hybrid dispersions were used as catalysts for hydrogenation reactions and the electroless plating of copper. In contrast to the conventional organoclay nanocomposites, the PMMA hybrid nanocomposites, containing simultaneously dispersed organoclay nanoplatelets together with organoclay supported silver nanoparticles, exhibited high antimicrobial activity against the ubiquitous bacterium Staphylococcus aureus, even at low silver content.

Metallized Organoclays as New Intermediates for Aqueous Nanohybrid Dispersions, Nanohybrid Catalysts and Antimicrobial Polymer Hybrid Nanocomposites

PMMA nanocomposites were prepared by means of self-assembly of polyhedral oligomeric silsesquioxanes (POSS) such as [Si8O12(OSiMe2H)8] (POSS1) and [Si7O9(cyclohexyl)7(OSiMe2H)3] (POSS2) during the free radical methyl methacrylate (MMA) bulk polymerization. The POSS phases separation and self-assembly afforded in situ nanocubes with average diameters ranging from 25 nm to 500 nm. The influence of 5.3 wt.% POSS on the thermal, mechanical and morphological PMMA nanocomposite properties was investigated. POSS mediated nanocube formation was accompanied by improvements of PMMA glass temperature and toughness. Depth profiling by means of ion beam Rutherford backscattering (RBS) analysis indicated the accumulation of POSS1 at the PMMA surface.

PMMA nanocomposites and gradient materials prepared by means of polysilsesquioxane (POSS) self-assembly

Poly(methyl methacrylate) (PMMA), polystyrene (PS), and polyurethane (PU) nanocomposites containing well-dispersed calcium phosphate/layered silicate hybrid nanoparticles were prepared in a versatile solvent-free “one-pot” process without requiring separate steps, such as organophilic modification, purification, drying, dispersing, and compounding, typical for many conventional organoclay nanocomposites. In this “one-pot” process, alkyl ammonium phosphates were added as swelling agents to a suspension of calcium/layered silicate in styrene, methyl methacrylate, or polyols prior to polymerization. Alkyl ammonium phosphates were prepared in situ by reacting phosphoric acid with an equivalent amount of alkyl amines such as stearyl amine (SA) or the corresponding ester- and methacrylate-functionalized tertiary alkyl amines, obtained via Michael Addition of SA with methyl acrylate or ethylene 2-methacryloxyethyl acrylate. Upon contact with the calcium bentonite suspension, the cation exchange of Ca2+ in the silicate interlayers for alkyl ammonium cations rendered the bentonite organophilic and enabled effective swelling in the monomer accompanied by intercalation and in situ precipitation of calcium phosphates. According to energy dispersive X-ray analysis, the calcium phosphate precipitated exclusively onto the surfaces of the bentonite nanoplatelets, thus forming easy-to-disperse calcium phosphate/layered silicate hybrid nanoparticles. Incorporation of 5–15 wt% of such hybrid nanoparticles into PMMA, PS, and PU afforded improved stiffness/toughness balances of the polymer nanocomposites. Functionalized alkyl ammonium phosphate addition enabled polymer attachment to the nanoparticle surfaces. Transmission electron microscopy (TEM) analyses of PU and PU-foam nanocomposites, prepared by dispersing hybrid nanoparticles in the polyols prior to isocyanate cure, revealed the formation of fully exfoliated hybrid nanoparticles.

A Versatile Solvent‐Free “One‐Pot” Route to Polymer Nanocomposites and the in situ Formation of Calcium Phosphate/Layered Silicate Hybrid Nanoparticles

A series of diacrylate macromonomers bearing alkoxysilyl units was prepared by convenient Michael addition of aminopropyl methyl diethoxysilane to 1,2-ethylene glycol diacrylate (EGDA), p-phenylene di-acrylate (PDA) and 1,4-cyclohexanediol diacrylate (CHDA). The resulting macromonomers have been characterized in detail by NMR spectroscopy, vapor pressure osmometry (VPO) measurements and fast-atom bombardment mass spectroscopy (FAB-MS). Average molecular weights Mn ranged between 530 and 1300 g . mol -1 (VPO). FAB-MS and size exclusion chromatography (SEC) showed the formation of a homologous macromonomer series. Viscosities of the liquid monomers are relatively low, ranging from 0.082 to 8.30 Pa . s. This renders these compounds interesting as reactive diluents in dental composite formulations. Upon polymerization of the macromonomers, low volumetric shrinkage occured, which was in the range of ΔV=2.4 and 3.9 vol-% at high conversion. Crosslinking was monitored by photo-differential scanning calorimetry (photo-DSC). Furthermore, composites were prepared by mixing 2,2-bis-[p-(2-hydroxy-3-methacryloxypropoxy)-phenyl]propane (Bis-GMA) with the new macromonomers, initiator and glass filler. The composites showed compressive strengths up to 244 MPa, flexural strengths from 22 to 42 MPa and Young's moduli between 870 and 3070 MPa. The composite materials exhibited low volume shrinkage of commercially available composites.

Hans Weickmann

Papers

Mechanical properties and electrical conductivity of carbon-nanotube filled polyamide-6 and its blends with acrylonitrile/butadiene/styrene

Metallized Organoclays as New Intermediates for Aqueous Nanohybrid Dispersions, Nanohybrid Catalysts and Antimicrobial Polymer Hybrid Nanocomposites

PMMA nanocomposites and gradient materials prepared by means of polysilsesquioxane (POSS) self-assembly

A Versatile Solvent‐Free “One‐Pot” Route to Polymer Nanocomposites and the in situ Formation of Calcium Phosphate/Layered Silicate Hybrid Nanoparticles

Acrylate‐Terminated Macromonomers by Michael Addition