In-situ radical polymerization

Grafting can also provide the monolithic polymers with rather unexpected properties. For example, the two-step grafting procedure summarized in Fig. 7, which involves the vinylization of the pore surface by reaction of the epoxide moiety with allyl amine, and a subsequent in situ radical polymerization of N-isopropylacrylamide (NIPAAm) initiated by azobisisobutyronitrile within these pores leads to a composite that changes its properties in response to external temperature [76]. 

Other methods derived from surface modification, including heterogeneous graft copolymerization or in situ radical polymerization and deposition of polyelectrolyte... 

As mentioned earlier, polymerization techniques can also be used in the presence of nanotubes for preparation of polymer/CNT nanocomposite materials. In these, in-situ radical polymerization techniques of polymerization in the presence of CNT filler under or without applied ultrasound. Both new factors (presence of CNT and ultrasound) can affect reaction kinetics, stability of suspension or the size of prepared particles. For example, ultrasound waves can open C=C bond of monomer, which starts polymerization initiation. Thus vinyl monomers (styrene, methyl methacrylate or vinyl acetate) can be polymerized without addition of initiator, only by application of ultrasound. This is called sonochemical polymerization method (15,33,34). 

Table 8.1. The influence of CNT content in polymerization mixture during in-situ radical polymerization on molecular weight of polymers and polydispersity index...

Susan, M.A., Kaneko, T., Noda, A. and Watanabe, M. (2005) Ion gels prepared by in situ radical polymerization of vinyl monomers in an ionic liquid and their characterization as polymer electrolytes. /. Am. Chem. Soc., 127, 4976M983. 

Fernandes et al (31) used laccase in combination with ultrasound to improve coloration of wool by in situ radical polymerization of catechol. The hydroxyl... 

Esteves ACC, Barros-Timmons A, Monteiro T et al (2005) Polymer encapsulation of CdE (E = S, Se) quantum dot ensembles via in-situ radical polymerization in miniemulsion. J Nanosci Nanotechnol 5 766-771... 

PMMA-T102 nanohybrid materials have been obtained by encapsulating surface-modified Ti02 nanoparticles into a PMMA network. PMMA was synthesized by in-situ radical polymerization of MMA initiated by 2,2 -azobisisobutyronitrile whereas the surface modification of the Ti02 nanoparticles was achieved by the formation of a charge transfer complex between the Ti02 surface and 6-palmitate ascorbic acid [177]. 

Dzunuzovic E, Jeremic K, Nedeljkovic JM (2007) In situ radical polymerization of methyl methacrylate in a solution of surface modified Ti02 and nanoparticles. Eur Polym J 43 (9) 3719-3726... 

Qin S, Qin D, Ford W T, Herrera J E, Resasco D E, Bachilo S M and Weisman R B (2004) Solubilization and purification of single-wall carbon nanotubes in water by in situ radical polymerization of sodium 4-styrenesulfonate, Macromolecules 37 3965-3967. 

Table 3 Formation of crystalline CaCOs with in-situ radical polymerization of N-vinyl-2-...

Bonhote, R Dias, A.-R Papageorgiou, N. Kalyanasundaram, K. Gratzel, M. Hydrophobic, highly conductive ambient-temperature molten salts, Inorg. Chem. 1996, 35, 1168-1178. Ohno, H. Functional design of ionic hquids, Bull. Chem. Soc. Jpn. 2006, 79, 1665-1680. Susan, M. A. B. H. Kaneko, T. Noda, A. Watanahe, M. Ion gels prepared by in situ radical polymerization of vinyl monomers in an ionic liquid and their characterization as polymer electrolytes, J. Am. Chem. Soc. 2005, 127, 4976 983. 

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... 

An early smdy on in situ polymerization was employed for the synthesis of PMMA-MWNT composites by fia and co-workers in 1999. In their reported work, in situ radical polymerization was performed using a radical initiator 2,2 -azobisisobutyronittile (AIBN) to initiate the ix bonds in CNTs to participate in the polymerization of PMMA, consequently forming a strong interface between the MWNTs and the PMMA matrix. Since then, some other groups have also used AIBN as an initiator of in situ radical polymerization to introduce functionalized MWNTs and SWNTs into PMMA matiices. """ """... 

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