• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.19-23
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• 2019

The PMMA (polymethyl methacrylate)/clay nanocomposites were synthesized by in situ radical polymerizations with different clay contents (3 and 7 wt%) using microwave heating. The nanostructure, optical, and thermal properties of the synthesized PMMA/clay nanocomposites were measured by XRD, TEM, AFM, UV-vis, and TGA. It was found that the intercalated- or exfoliated structure of PMMA/clay nanocomposites was strongly dependent on the content of clay. Thus, the imposition of microwave-assisted polymerization facilitated a delamination process of layered silicates to achieve exfoliation state of interlayer distance. The PMMA/3 wt% C10A nanocomposite with well-dispersed and exfoliated clay nano-layers showed the good optical transparency similar to pure PMMA in this study. The thermal decomposition rates of the PMMA/clay nanocomposites become to be lower compared to that of the pure PMMA, indicating the intercalated- or exfoliated inorganic silicate has high thermal stability. A possible reason is that the thermally segmental motion of PMMA polymer into inorganic silicate interlayer spacing has increased the thermal stability of the PMMA/clay nanocomposites.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.252-257
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• 2010

Nanocomposites of blends of polymethyl methacrylate (PMMA) and poly (styrene-co-maleic anhydride) (SMA) containing natural and organically modified montmorillonite clays ($Cloisite^{(R)}$25A and $Cloisite^{(R)}$15A) were prepared by solution mixing. Effect of clay on the miscibility, morphology and thermal properties of nanocomposites was investigated. DSC results showed that the addition of clay improved the miscibility of PMMA/SMA blends. Specifically, clay 15A was observed to be most effective than other clays in all nanocomposites regardless of MA contents of SMAs tested. Dispersion of clays was investigated using XRD and TEM and the nanocomposites containing clay 15A again showed the best clay dispersion than the ones with other clays.

• Macromolecular Research
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• v.10 no.4
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• pp.187-193
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• 2002

Several methods have been used to synthesize polymer-clay nanocomposites. In-situ polymerization with clay belongs to a classical way to develop nano-structured materials, while melt intercalation is being recognized as another useful approach due to its versatility and environmentally benign character. In this research, we prepared polymer-clay nanocomposites based on the poly (methyl methacrylate) and organically modified montmorillonite via two-stage sonication process. According to the unique mode of power ultrasonic wave, the sonication during processing led to enhanced breakup of the clay agglomerates and reduction in size of the dispersed phase. Optimum conditions to form stable exfoliated nanocomposites were studied for various compositions and conditions. It was found that a novel attempt carried out in this study yielded further improvement in the mechanical performance of the nanocomposites compared to those produced by the conventional melt mixing process, as revealed by DMA, XRD and TEM. And rheological properties of nanocomposites were measured by ARES. As a result, sonicated PMMA-clay nanocomposites exhibits enhanced properties such as storage modulus and thermal stability than that of neat PMMA.

• Macromolecular Research
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• v.11 no.6
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• pp.410-417
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• 2003

Poly(methyl methacrylate-co-acrylonitrile) [P(MMA-co-AN)]/Na-MMT nanocomposites were synthesized through emulsion polymerization with pristine Na-MMT. The nanocomposites were exfoliated up to 20 wt% content of pristine Na-MMT relative to the amount of MMA and AN, and exhibited enhanced storage moduli, E', relative to the neat copolymer. The exfoliated morphology of the nanocomposite was confirmed by XRD and TEM. 2-Acryla-mido-2-methyl-1-propane sulfonic acid (AMPS) widened the galleries between the clay layers before polymerization and facilitated the comonomers, penetration into the clay to create the exfoliated nanocomposites. The onset of the thermal decomposition of the nanocomposites shifted to a higher temperature as the clay content increased. By calculating areas of tan$\delta$ of the nanocomposites, we observed that the nanocomposites show more solid-like behavior as the clay content increases. The dynamic storage modulus and complex viscosity increased with clay content. The complex viscosity showed shear-thinning behavior as the clay content increased. The Young's moduli of the nano-composites are higher than that of the neat copolymer and they increase steadily as the silicate content increases, as a result of the exfoliated structure at high clay content.

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.231-237
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• 2014

The supercritical fluids (SCFs) have been widely used for material synthesis and processing due to their remarkable properties including low viscosity, high diffusivity and low surface tension. Carbon dioxide is one of the suitable solvents in SCFs processes in terms of its advantages such as easy processibility (with low critical temperature and pressure), inexpensive, nonflammable, nontoxic, and readily available. However, it has generally low solubility for high molecular weight polymers with the exception of fluoropolymers and siloxane polymers. Therefore, hydrocarbon solvents and hydrochlorofluorocarbons have been used for various SCFs process by its high solubility for high molecular weight polymers. In this report, a PMMA/clay nanocomposites were fabricated by using supercritical fluid process. The $Na^+$-MMT(montmorillonites)was modified by a fluorinated surfactant which is able to enhance compatibility with the chlorodifluoromethane(HCFC-22) and thus, improve dispersability of the clay in the polymer matrix. The PMMA/fluorinated surfactant modified clay nanocomposite shows enhanced mechanical and thermal properties which characterized by X-raydiffraction(XRD), Thermo gravimetric analysis(TGA), Dynamic mechanical analysis (DMA) and Transmission electron microscopy (TEM).