Poly polymer-clay nanocomposites

Y. Hu, Y. Tang, and L. Song, Poly(propylene)/clay nanocomposites and their application in flame retar-dancy, Polym. Adv. Technol., 2006, 17 235-245. 

ATRP was also combined with other polymerization methods in the preparation of polymer clay nanocomposites. Yang and coworkers reported the preparation of poly(L-lactide) (PLLA) comb polymer brushes on the surface of sihcate layers by using a combination of in-situ ATRP and ROP (Figure 10.7) [34]. An ATRP initiator with a quaternary ammonium salt end group was intercalated into the interlayer spacing of clay layers via ion exchange. In-situ ATRP of hydroxyethyl methacrylate (HEMA) in the presence of CuBr and bipyridine afforded the PHEMA backbone. PLLA comb polymers were grown from the PHEMA backbone by ROP. Because... 

Takahashi N, Kuroda K (2011) Materials design of layered silicates through covalent modification of interlayer surfaces. J Mater Chem 21(38) 14336-14336 Tasdelen MA (2011) Poly( -caprolactone)/clay nanocomposites via click chemistry. Eur Polym J 47(5) 937-941... 

A model poly(ethylene oxide)/laponite hybrid material, characterized by a high silicate content, was used to probe the dynamical behaviour of polymer chains at the surface with clay platelets. Such a system mimics the intercalated phases that may occur in polymer/clay nanocomposites. The segmental motions of this system were monitored over the tens of microseconds time scale by means of C and H solid-state NMR. A significant slowing down of these motions was mostly observed, as compared to the local dynamics in the amorphous phase of neat PEO. ... 

In the case of polymer/clay nanocomposites, alkylammonium exchange species influence the affinity between the polymer and the clay surface. For example, it was reported that clays treated with dialkyl dimethylammonium halides, in particular with two chains of about 18 carbon atoms, have a surface energy similar to poly(olefins) such as polypropylene (PP) and polyethylene (PE) [27]. Polar polymers as polyamides (PA) have been recommended to get better interactions as reported by Toyota [8]. The alkyl chain length is related with increase in interlayer space required for the intercalation of polymer chains. Because of the nonpolar nature of their chains, they reduce the electrostatic interactions between the silicate layers and lower the surface energy of the layered silicates. As a consequence, an optimal diffusion of the polymer to dissociate the stacked clay layers, that is, an exfoliation process, can be obtained. Despite the compatibility of MMT modified by long alkyl chain quaternary ammonium with hydrophobic polymers (PE and PP), conventional alkylammonium ions show low thermal stability, that is, an onset decomposition temperature is close to 180°C.This poor thermal stability could limit their use in the preparation of PLS with matrices processed at high temperatures such as PA, poly(ethylene terephthalate) (PET), and poly(ether ether ketone) (PEEK) [30]. 

Kumar S., Jog J. R, and Natarajan U., Preparation and characterization of poly (methylmethacrylate)-clay nanocomposites via melt intercalation The effect of oigano-clay on the structure and thermal properties. Journal of Applied Polymer Science 2003, 89, 1186-1194. 

Haraguchi, K., Li, H.-J., Song, L., Murata, K., 2007. Tunable optical and swelUng/deswelUng properties associated with control of the coil-to-globule transition of poly(A-isopropylacrylatnide) in polymer-clay nanocomposite gels. Macromolecules 40,6973—6980. 

Lepoittevin, B., Devalckenaere, M., Pantoustier, N., Alexandre, M., Kubies, D., Calberg, C., Jerome, R., Henrist, C., Cloots, R., Rulmont, A., Dubois, Ph., 2002, Poly( -caprolactone)/clay nanocomposites prepared by melt intercalation mechanical, thermal and rheological properties. Polymer 43 4017-4023. 

Preschilla, N., Sivalingam, G., Rasheed, A.S.A., Tyagi, S., Biswas, A., and Bellare, J.R. (2008) Quantification of organoclay dispersion and lamellar morphology in poly(propylene)-clay nanocomposites with small angle X-ray scattering. Polymer, 49, 4285 297. 

G. W. Beall and D. Adame. Direct measurement of the constrained polymer region in poly amide/clay nanocomposite. Applied Clay Science (submitted 2007). 

Yeh, J.M., Chin, C.P. Structure and properties of poly(omethoxyanihne) clay nanocomposites materials , Jo rwa/ of Applied Polymer Science, 2003,88,1072-78. 

Yeh J. M., Liou S. J., Lai M. C., Chang Y. W., Eluang C. Y. et al. (2004c), Comparative Studies of the Properties of Poly(methylmethacrylate)-clay Nanocomposite Materials Prepared by in situ Emulsion Polymerization and Solution Dispersion. JAppl Polym Sc, 94, 1936 6. 

Biodegradable Polymer-Clay Nanocomposite Fire Retardants PMMA poly(methyl methacrylate)... 

Yoon et al. also reported the preparation of poly(styrene-co-divinylbenzene)-clay (polymer-clay) nanocomposites by y-irradiation copolymerization.The intercalated structure of the polymer-clay nanocomposites was observed by XRD and energy-filtered transmission electron microscopy (EF-TEM). The enhancement of the thermal properties of the polymer-clay nanocomposites was confirmed via TGA. The mechanism of the intercalate structure formation in y-irradiation polymerization was explained as shown in Figure 8.1. 

The polymer-clay nanocomposites with core-poly(butyl acrylate) (PBA) intercalated organophilic montmorillonite (OMMT) and shell-PS were successfully prepared using y-irradiation emulsion polymerization by Wang et al., as shown in Figure 8.3. The prepared core-PBA-OMMT and shell-PS structure nanocomposites can be incorporated in a pure PS matrix the impact strength of the blend was dramatically improved and the tensile strength of PS also remained high. 

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