In Situ Polymerization Method

Several techniques may be used to produce polymer-MMT nanocomposites, including in-situ polymerization, melt intercalation, and solution casting however, to date in-situ polymerization has produced the best dispersed systems for PS-MMT nanocomposites [8]. This technique offers the advantage of allowing the monomer to penetrate the intergallery spaces first, which aids the exfoliation process. If the polymerization reaction can occur between the clay layers, the delamination process is further enhanced as growing polymer chains can push the clay layers apart, which is the main reason for the superior dispersed systems observed [8]. There are several in-situ polymerization techniques which may be used to form 

PS nanocomposites, including bulk free radical plymerization, solution and emulsion polymerizations, as well as controlled polymerization techniques such as RAFT, NMP, and ATRP. 

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SCHEME 2.3 The in situ polymerization method for nanocomposite preparation. 

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... 

Other microcapsules are produced by surface and in situ polymerization methods or, generally, interfacial reactionsThe capsule walls may be soluble or insoluble and impermeable or permeable, whereby the rate of release of the encapsulated material or the exchange of material through the membrane walls can be adjusted and controlled. Originally, drugs, chemicals, toner materials, pigments, and the like were encapsulated to improve handling and... 

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. 

Microencapsulation techniques make use of sol-gel processes, coacervation, surface and in situ polymerization methods or, generally, interfacial reactions to produce soluble or insoluble and impermeable or permeable capsule walls. In addition to the coating and spray drying methods that were discussed previously, a growing number of other processes deposit particles onto cores or solid surfaces whereby the binding mechanisms of agglomeration are utilized [B.97] (Chapter 11). 

Sawada, K., Urakawa, H., 2005. Preparation of photosensitive colour-producing microcapsules utilizing in situ polymerization method. Dyes and Pigments 65 (1), 45—49. 

It should be noted that among the three different methods of PNC preparation mentioned above, the solution method and the in situ polymerization method have only limited applications because neither a compatible polymer-silicate solvent system nor a suitable monomer is always available. Moreover, they are not always compatible with current polymer processing techniques. Among all the methods to prepare PNCs, the approach based on direct melt mixing/intercalation is perhaps the most versatile and environmentally benign. 

Coaxial PMMA/PANI composite nanofibers have also been fabricated using the electro-spinning technique and an in situ polymerization method and were then transferred to the surface of a gold interdigitated electrode to constmct a gas sensor (Figure 4.22) [102]. It was... 

The most used MPCMs have paraffin wax as core material and PMMA as a shell. Commercially, this type is the one MPCM available. Nowadays, there are several studies with organic, eutectic, and inorganic salts as PCM in MPCM. Emulsion polymerization and in situ polymerization method are the two more employed to create MPCM. Moreover, DSC is the most employed technique to measure MPCM main thermophysical properties. 

In the in situ polymerization method, the layered silicate is swollen within the liquid monomer or a monomer solution so the polymer formation can occur between the layered silicates. Polymerization can be initiated by either heat or radiation, by the... 

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]. 

Due to the enhanced conductivity and consequent improved electrochemical performance, the cathode materials of conjugated polymers/ inorganic have attracted much attention in a wide range, and some novel nanostructures have been recently proposed. Mai et al. reported the preparation of coaxial or triaxial nanowires of MoO and AgVO coated with conducting PTh or PANI based on the in situ polymerization method [29,76], and the capacity retention rates were significantly enhanced due... 

R. Zhang, Z. Shi, Y. Liu, and J. Yin, Synthesis and characterization of polybenzimidazole-nanodiamond hybrids via in situ polymerization method. Journal of Applied Polymer Science, 125 (4), 3191-3199,2012. 

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],... 

He, R-A. and Zhang, L.-M. 2007. New polyethylene nanocomposites prepared by in-situ polymerization method using nickel a-diimine catalyst supported on organo-modified ZnAl layered double hydroxide. Composites Science and Technology 67 3226-3232. 

According to the in situ polymerization method, the catalyst should be intercalated and fixed within the filler layers and the exfoliation degree should be dependent on the concentration of active sites formed between the silicate layers. To facilitate the intercalation... 

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

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. 

The authors considered this organic modification removal as a result of reactions between oxygen atoms in MMAO and ammonium ions. They also compared three different in-situ polymerization methods performed under atmospheric pressure of ethylene ... 

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