Transmission electron microscopy polymerization

Nylon-6. Nylon-6—clay nanometer composites using montmorillonite clay intercalated with 12-aminolauric acid have been produced (37,38). When mixed with S-caprolactam and polymerized at 100°C for 30 min, a nylon clay—hybrid (NCH) was produced. Transmission electron microscopy (tern) and x-ray diffraction of the NCH confirm both the intercalation and molecular level of mixing between the two phases. The benefits of such materials over ordinary nylon-6 or nonmolecularly mixed, clay-reinforced nylon-6 include increased heat distortion temperature, elastic modulus, tensile strength, and dynamic elastic modulus throughout the —150 to 250°C temperature range. 

Paine et al. [99] tried different stabilizers [i.e., hydroxy propylcellulose, poly(N-vinylpyrollidone), and poly(acrylic acid)] in the dispersion polymerization of styrene initiated with AIBN in the ethanol medium. The direct observation of the stained thin sections of the particles by transmission electron microscopy showed the existence of stabilizer layer in 10-20 nm thickness on the surface of the polystyrene particles. When the polystyrene latexes were dissolved in dioxane and precipitated with methanol, new latex particles with a similar surface stabilizer morphology were obtained. These results supported the grafting mechanism of stabilization during dispersion polymerization of styrene in polar solvents. 

Recent demands for polymeric materials request them to be multifunctional and high performance. Therefore, the research and development of composite materials have become more important because single-polymeric materials can never satisfy such requests. Especially, nanocomposite materials where nanoscale fillers are incorporated with polymeric materials draw much more attention, which accelerates the development of evaluation techniques that have nanometer-scale resolution." To date, transmission electron microscopy (TEM) has been widely used for this purpose, while the technique never catches mechanical information of such materials in general. The realization of much-higher-performance materials requires the evaluation technique that enables us to investigate morphological and mechanical properties at the same time. AFM must be an appropriate candidate because it has almost comparable resolution with TEM. Furthermore, mechanical properties can be readily obtained by AFM due to the fact that the sharp probe tip attached to soft cantilever directly touches the surface of materials in question. Therefore, many of polymer researchers have started to use this novel technique." In this section, we introduce the results using the method described in Section 21.3.3 on CB-reinforced NR. 

Chemical fixation for transmission electron microscopy prepares cells for the preservation of damage due to subsequent washing with aqueous solvents, dehydration with organic solvents such as ethanol or acetone, embedding in plastic resins, polymerization of the resins by heat, exothermic catalysts, or ultraviolet radiation, and imaging with high-energy electron beams in an electron microscope. 

Recently, Kroeze et al. prepared polymeric iniferter 34 including poly(BD) segments in the main chain [152]. They successfully synthesized poly(BD)-block-poly(SAN), which was characterized by gel permeation chromatography, elemental analysis, thermogravimetric analysis, NMR, dynamic mechanical thermal analysis, and transmission electron microscopy. By varying the polymerization time and iniferter concentration, the composition and the sequence length were controlled. The analysis confirmed the chain microphase separation in the multiblock copolymers. 

Many hydrogenation and polymerization reactions in the chemical industry are carried out with liquid-phase reactants. An example is the hydrogenation of aliphatic dinitriles to produce diamines (108,109), which are subsequently converted with adipic acid in solution and polymerized to produce linear polyamides, including nylon 6,6. Recently, the development of wet-environmental transmission electron microscopy (wet-ETEM) for direct nanoscale probing of... 

After polymerization was complete, transmission electron microscopy was carried out on thin sections of the 10/90 and 20/80 compositions. Confirming the optical micrographs, the polystyrene phase was continuous for the fully reacted product. As illustrated in Figure 5 for the 10/90 system, the oil phase (stained dark) contains a considerable amount of occluded polystyrene. For the 20/80 system, data not shown, dual phase continuity was found. The polystyrene phase was relatively pure, but the oil-rich phase had much occluded... 

The polymer resulting from oxidation of 3,5-dimethyl aniline with palladium was also studied by transmission electron microscopy (Mallick et al. 2005). As it turned out, the polymer was formed in nanofibers. During oxidative polymerization, palladium ions were reduced and formed palladium metal. The generated metal was uniformly dispersed between the polymer nanofibers as nanoparticles of 2 mm size. So, Mallick et al. (2005) achieved a polymer- metal intimate composite material. This work should be juxtaposed to an observation by Newman and Blanchard (2006) that reaction between 4-aminophenol and hydrogen tetrachloroaurate leads to polyaniline (bearing hydroxyl groups) and metallic gold as nanoparticles. Such metal nanoparticles can well be of importance in the field of sensors, catalysis, and electronics with improved performance. 

Figure 7.1. (a) Transmission electron microscopy image of a collection of 200-nm magnetic emulsion droplets obtained from emulsifying an octane-based ferrofluid. (b) One droplet is shown after polymerization. A polymer shell is visible that encapsulates the iron oxide nanoparticles. (With permission of Ademtech). 

Fig. 4. Transmission electron microscopy of MTP reaction mixtures, (a) An opened area is seen in a microtubule polymerized in the presence of an IC concentration (3 x 10 W) of deoxydesethyl VBL (5). (b) Single spirals are formed from MTP and 10 M 5. (c) Spiral aggregates are formed from MTP and 10 M VBL. (d) MTP incubated with an lCs concentration (2 X 10 Af) of epimethyldeoxydesethyl VBL (4) formed spiral aggregates both free in solution (single arrows) and associated with microtubules (double arrows), (e) Greater magnification of MTP incubated with an 1C , concentration (2 x 10 M) of methyldeoxyde-sethyl VBL (3) displays a free spiral (arrow) and spiralized material on the microtubules. Bar, 0.1 p.m.

Spherical gold nanoparticles coated with poly(N-isopropylacrylamide) (PNIPAM) grafts have been synthesized by controlled radical polymerization. The polymerization of N-isopropylacrylamide was initiated from the surface of the nanoparticles modified with 4-cyanopentanoic acid dithiobenzoate for reversible addition-fragmentation chain-transfer polymerization. The mean diameter of the Au core was 3.2 nm, as observed by means of high-resolution transmission electron microscopy [90]. 

The dispersions were obtained by emulsification via ultrasonication of a toluene solution of the unsaturated homopolymer in an aqueous surfactant solution. This was followed by exhaustive hydrogenation with Wilkinson s catalyst at 60°C and 80 bar H2 to produce a dispersion with an average particle size of 35 nm (dynamic light scattering and transmission electron microscopy analyses). The same a,co-diene was used as comonomer in the ADMET polymerization of a phosphorus-based monomer, also containing two 10-undecenoic acid moieties... 

Due to the high water solubility of MAA, partitioning of the MAA in the water phase was expected. After polymerization, the obtained miniemulsions (latexes) and the colloidal nanoMIPs were characterized by gravimetric analysis, dynamic light scattering (DLS), gas adsorption measurements (BET), and transmission electron microscopy (TEM) as shown in Fig. 9. 

The various latexes were characterized with respect to particle size and size distribution, surface charge and functional group density, and electrophoretic mobility behavior. As observed by transmission electron microscopy all latexes were found highly monodisperse with a uniformity ratio between 1.001 and 1.010, a property due to the short duration of the nucleation period involved in the various radical-initiated heterogeneous polymerization processes. The surface charge density was determined by a colorimetric titration method reported elsewhere [13]. 

It is obvious from Fig. 12 that crack formation does not start at emergent imperfections which has been confirmed by transmission electron microscopy (see Sect. IV.b.)59. The scanning electron micrographs of poly-DSP and poly-P2VB44) crystals are quite different. The difference may be reflected by a crystal volume change during polymerization in which the DSP crystals shrink while the P2VB crystals expand. 

By tuning the relative composition and degree of polymerization (DP) of the two segments, phase-separated microstructures were formed in thin films of the copolymer. Specifically, dynamic mechanical analysis (DMA) and transmission electron microscopy (TEM) observations revealed that, for a small molar ratio of p(MA-POSS)/pBA (DP = 6/481/6), no evidence of microphase separation was evident while a large ratio (1 2 1) revealed strong microphase separation (Fig. 8) [122]. 

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