Composite nano-, polymeric

For scratch resistance improvement of organic surfaces also nano-composites are of interest. In a composite nano-scale boehmite or y-aluminia particles of about 15 nm diameter have been used as catalysts for epoxy groups linked to hydrolyseable and condensable silanes. Epoxy polymerization preferably takes place around the nanoparticles and additionally =Si-0-Al= bonds are formed between the silanes and the alumina surface [486]. It seems that the nano-particles, only 5% in volume fraction, are flexibly suspended in an inorganic-organic network. Such systems can be produced as transparent coatings and cured at relatively low temperatures of 90 to 120°C to high performance scratch resistant layers. 

If two or more types of different materials are mixed up and treated in defined conditions (varying with temperature, pressure, and other chemical and physical processes), a composite material with a clear interfacial boundary will be obtained. If a major part of the produced composite consists of polymer, then it is called a polymeric composite. A polymeric composite material is one of the most developed areas of modern science and technology. In addition to composite materials, modern science and technology use nano-sized materials. Such composites are called nanocomposites, whose main attraction is related to very high operation properties, such as flexibility, elasticity, recycling, hardness, resistance to abrasion, and optical and electrical transmission [9]. 

Nano-composites (NCs) are materials that comprise a dispersion of particles of at least one of their dimentions is 100 nm or less in a matrix. The matrix may be single or multicomponent. It may include additional materials that add other functionalities to the system such as reinforcement, conductivity and toughness (Alexandre and Dubois, 2000). Depending on the matrix, NCs may be metallic (MNC), ceramic (CNC) or polymeric (PNC) materials. Since many important chemical and physical interactions are governed by surface properties, a nanostructured material could have substantially different properties from large dimensional material of the same composition (Hussain et ah, 2007). 

D-TEM was introduced into rubber technology field in 2004 by the authors of this chapter [4]. In a recent review of 3D-TEM applied in materials science field [5], only two papers were cited on polymeric samples—one on block copolymers [6] and the other on rubbery composites with conventional and in situ silica [4]. Starting from the latter, 3D-TEM measurements have been carried out on rubbery nano-composites [7-16], and this recent and very important topic is described in this review. 

H.J. Barraza, F. Pompeo, E.A. O Rear, and D.E. Resasco, SWNT-filled thermoplastic and elastomeric composites prepared by miniemulsion polymerization. Nano Lett. 2, 797-802 (2002). 

Suspension arrays are based on addressable nano- or micrometric beads of various chemical natures (polymeric, silica, gold) and architectures (uniform composition, core-shell particles) to which NAs can be immobilized by means of activating chemistries similar to those described for fiat supports [64,65] depending on the composition of the particles outmost layer. 

In another interesting development, Yei et al. [124] prepared POSS-polystyrene/clay nanocomposites using an emulsion polymerization technique. The emulsion polymerization for both the virgin polystyrene and the nano composite started with stirring a suspension of clay in deionized water for 4h at room temperature. A solution of surfactant ammonium salt of cetylpyridinium chloride or POSS was added and the mixture was stirred for another 4 h. Potassium hydroxide and sodium dodecyl sulphate were added into the solution and the temperature was then raised to 50 °C. Styrene monomer and potassium persulfate were later on added slowly to the flask. Polymerization was performed at 50 °C for 8 h. After cooling, 2.5% aqueous aluminium sulphate was added to the polymerized emulsion, followed by dilute hydrochloric acid, with stirring. Finally, acetone was added to break down the emulsion completely. The polymer was washed several times with methanol and distilled water and then dried overnight in a vacuum oven at 80 °C. The obtained nanocomposite was reported to be exfoliated at up to a 3 wt % content of pristine clay relative to the amount of polystyrene. 

Nano-composites for optoelectronics Sensors using zeolite thin films Stereo-selective polymerization Contrast enhancement in MRl (e.g. Gd-Y)... 

The new generation of magnetic elastomers and gels represent a new type of composites, consisting of small (mainly nano- and micron-sized) magnetic particles dispersed in a high elastic polymeric matrix [11-51]. These materi-... 

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