In situ polymerization method, for

SCHEME 2.3 The in situ polymerization method for nanocomposite preparation. 

Olefin in-situ polymerization methods for the production of polyolefin-clay nanocomposites still face many challenges before becoming industrially relevant. 

Wang et al. (2002) compared various in situ polymerization methods for the preparation of PMMA/clay nanocomposites. It was found that the particular preparative technique that is used has a large effect on the type of nanocomposites (in terms of nanoclay dispersion) that may be obtained. Solution polymerization of MMA only yields intercalated nanocomposites regardless of the presence of polymerizable double bond in the intergallery region. On the other hand, emulsion, suspension, and bulk polymerization can yield either exfoliated (with intergallery double bond) or intercalated (without double bond present) nanocomposites. 

Pande et al. (25) also reported significant improvements in the flexural properties of MWCNT-PMMA composites prepared by in-situ polymerization method. They observed a maximum reinforcing effect of CNTs at 3 wt% for a-MWCNT and at 1.8 wt% for f-MWCNT. The flexural strength for the two cases was about 90 MPa as compared to about 64 MPa from two step method... 

An important development, pioneered by Kuhn and coworkers,37 38 has been the deposition of conducting PAn s onto fibers and fabrics. Not only hydrophobic fibers such as polyesters and polypropylene but also hydrophilic textiles such as rayon and cotton can be coated with PAn with this in situ polymerization method. PAn/nylon-6 composite films have also been prepared by adsorbing aniline onto thin nylon-6 films and then treating with aqueous (Nn4)2S208.39 The composite films exhibited a low percolation threshold requiring just 4% PAn for electrical conductivity. 

Once the imprinting system has been devised to yield favorable monomer-template complexation and the necessary porosity, the preparation of monolithic polymer rods for HPLC is relatively simple. The general protocol detailed below uses an in situ polymerization method developed by Frechet and Svec [4]. This technique was used by Matsui in the preparation of MIP monolith rods for HPLC separation of antimalarial cinchona alkaloids, ( ) cinchonidine and (+) cinchonine, as well as the structural analogues quinidine and quinine [45]. 

Wang and coworkers synthesized the PPy/V O hollow micro-spherical hybrid by in-situ polymerization method as cathode material for LIB. Compared to bare electrode (32.7% retention), this PPy/oxide cathode exhibits slightly reduced capacity and substantially improved cyclabil-ity (89.1% retention after 50 cycles), and it was demonstrated that the reduction in the capacity is due to the partial reduction of vanadium during the polymerization of polymer [41],... 

In this method, the organoclay, the catalyst precursor, and the activator (alkylalu-minum compounds or alkylaluminoxanes) are added to the reactor and the polymerization is started by introduction of the olefin monomer. This is the simplest in-situ polymerization method, and only few reports [1, 51, 70, 71] have been published investigating this method for production of polyolefin-clay nanocomposites. In comparison to the other in-situ polymerization methods, this method seems to have the lowest polymerization activities, although it is often difficult to compare catalysts activities for polymerizations done at very different conditions and following distinct procedures. 

Kim et al. [19] fabricated PET/clay composites using a two-step in-situ polymerization method. In the first step, a slurry mixture of monomer (purified tereph-thalic acid and ethylene glycol), polycondensation catalyst, clays, and some additives was kept at 250 °C for 5-6h in the esterification step. Then, it was transferred to a polycondensation reactor until the intrinsic viscosity (IV) value reached 0.6dlg" . Then, the materials were pelletized. Furthermore, a solid-state polymerization (SSP) process is carried out to conduct the polymerization process further. SSP was carried out at between 220 and 145 °C for around 8h until the IV reached 0.8dlg . ... 

Ruiz I, Hermida EB, Baldessari A (2011) Fabrication and characterization of porous PHBV scaffolds for tissue engineering. J Phys Conf Ser 332 1-10 Sahoo NG, Jung YC, So HH, Cho JW (2007) Synthesis of pol50irethane nanocomposites of functionalized carbon nanotubes by in-situ polymerization Methods. J Korean Physycal Soc 5LS1-S6... 

The second preparation method uses polymer solutions and involves a strategy similar to the in situ polymerization method. However, this method is only suitable for polymers such as polyethylene oxide (PEO) and polyacrylic acid (PAA) that are soluble in polar solvents, or for soluble polymeric precursors in the case of polymers insoluble in organic solvents, such as polyimide (PI) [33,4,46]. 

A new type of biobased material was synthesized from cellulose nano whiskers (CW) and furfuryl alcohol by employing in-situ polymerization method to produce polyfur-furyl alcohol (PFA)/cellulose nanocomposites without the use of solvents or surfactants. Furfuryl alcohol (FA) played a dual role, serving both as an effective dispersant for the cellulose whisker (CW) and as the matrix precursor for the in-situ polymerization. The filler, CW also served multiple functions, by first catalyzing the polymerization of FA, and then acting as an effective matrix modifier, increasing the thermal stability of the consolidated PFA nanocomposite. The polymerization was catalyzed by sulfonic acid residues at the CW surface left over from the whisker preparation [67]. 

Table 8.2 shows TGA data for PS-OMT-ArP nanocomposites prepared by the in situ polymerization method, including the onset degradation temperature at which 10% of the sample was lost the midpoint of the degradation... 

Unlike melt intercalation, a layered silicate is mixed with monomer before polymerization takes place with in situ polymerization. This method was developed by Toyota researchers [27,28], in which electrostatically held 1-nm thick layers of layered alumina silicates were dispersed in a polyamide matrix on a nanometer level, which led to an exponential growth in the research endeavors, in layered silicate nanocomposites. These nanocomposites were based on the in situ synthesis approach in which a monomer or monomer solution was used to swell the filler interlayers, followed by polymerization. With this process, one can control the nanocomposite morphology through the combination of reaction conditions and clay surface modification. The in situ polymerization method is especially important for insoluble and thermally unstable polymers, which solution blending or melt blending technique cannot process. 

Early, in situ radical polymerization was used for the synthesis of poly(methyl methacrylate) (PMMA)-CNT composites [82]. In situ polymerization was performed using the radical initiator 2,2-azobisisobutyronitrile(AIBN). In this reaction, p-bonds in CNTs were initiated by AIBN, and therefore nanotubes could participate in PMMA polymerization to form a strong interface between the CNT and the PMMA matrix. PA6/CNT composites have been prepared by in situ polymerization of e-caprolactam in the presence of pristine and carboxylated CNTs. The e-caprolactam monomer was found to form an electron-transfer complex with CNTs and result in a homogeneous, polymerizable solution. The final composites can be spun into PA6/CNT fibers (Fig. 7) with excellent mechanical and electrical properties [83].This method is also suitable for the fabrication of thermosetting polymer composites with nanofillers. Bauhofer et al. [84] dispersed CNTs in an epoxy solution system based on a bisphenol-A epoxy resin and an amine hardener During nanocomposite curing, electric fields were used to induce the formation of aligned conductive nanotube networks. Recently, the in situ polymerization method... 

As mentioned earlier in situ approach has also been used for the synthesis of conducting polymer-metal hybrid nanocomposites. Xu et al. [35] have reported the decoration of PPy nanotubes with gold nanoparticles by an in situ reduction process. They prepared PPy nanotubes by MO-FeCl3 self-degrade template method and then reduced HAuCLi within PPy nanotubes in the presence of different surfactants such as sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and Tween-80. Nanowires of silver PAni nanocomposites have been reported via in situ polymerization method [36]. In this method aniline is oxidized by ammonium persulfate (APS) in the presence of dodecylbenzene sulfonic acid (DBSA) and silver nitrate (AgN03). In another approach gold-PAni core-shell... 

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