Poly methyl methacrylate PMMA -based Nanocomposites

1 Poly(methyl methacrylate) (PMMA)-based Nanocomposites 

Zhang et al ° obtained a CNT-polymer composite by infiltration of a monomer liquid into aligned CNT aerogel fibers with subsequent in situ polymerization. PMMA/MWNT composite fibers showed that the PMMA filled the spaces of the nanotube fibers and bound the nanotubes together. PMMA in the composite fibers exhibited local order. The resultant composite fibers with 15 wt% nanotube loading exhibited a 16-fold and a 49-fold increase in tensile strength and Young s modulus, respectively, compared with the control PMMA. 

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The wide assortment of polymer systans (polypropylene, poly(methyl methacrylate) [PMMA], polyepoxide, polystyrol, PC, etc.) is used as a polymeric matrix for nanocomposites production (Ray and Okamoto 2003). The most well-known fillers of polymeric matrix are nanoparticles (silica, metal, and other organic and inorganic particles), layered materials (graphite, layered aluminosilicates, and other layered minerals), and fibrous materials (nanofibers and nanotubes) (Thostenson et al. 2005). Nanocomposite polymer materials containing metal or metal oxide particles attract growing interest due to their specific combination of physical and electric properties (Rozenberg and Tenne 2008, Zezin et al. 2010). Nanocomposites on the base of layered materials... 

For polymeric nanomaterials, another source of toxicity comes from unreacted monomers, residual reaction agents (e.g., aoss-linking initiators), or additives (e.g., surfactants) in the fabrication processes [21]. These substances may leach out and release to tissue when the nanopolymers or nanocomposites interact with body fluids or degrade. For instance, monomers of A-isopropylacrylamide and methyl methacrylate that forms PNlPAAm and poly(methyl methacrylate) (PMMA), respectively, are toxic and carcinogenic or teratogenic. As a result, medical products based on PNlPAAm and PMMA always require careful control of fabrication parameters and processes to minimize the umeacted monomers or residues [22]. 

The purpose of the present chapter is to illustrate with the presentation of some chosen examples how broadly the latex-based concept can be applied to all kinds of polymer systems. I n this respect, several composites were prepared with various polymer matrixes. Emphasis was put on the use of alternative continuous nanocomposite phases other than "single amorphous polymers such as poly [methyl methacrylate) [PMMA) and polystyrene [PS], which have already been reported in detail in Chapter 4. These alternative systems are... 

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... 

Figure 3.3. Tensile properties of PP (MFI = 6.7 g/10 min) based nanocomposites as a fmic-tion of Si02 content (a) tensile strength (b) Young s modulus (c) elongation to break and (d) area under stress-strain curve [3]. (Si02-g-PMMA means poly(methyl methacrylate) grafted nano-Si02)...

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