Insight into molecular interactions between constituents in polymer clay nanocomposites

Sikdar, Debashis; Katti, Dinesh R.; Katti, Kalpana S.; Bhowmik, Rahul

doi:10.1016/j.polymer.2006.05.026

Cited by 64 publications

(29 citation statements)

References 60 publications

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“…It is wellknown, both from simulation [14][15][16][43][44][45][46][47] and from experimental studies, 32,34 that the presence of layered silicates in a polymer matrix causes modifications in the chain conformation next to the particle surface. In particular, considering the density of the organic species, there seems to be a tendency of the quats and polymer chains to adopt a layered conformation.…”

Section: Simulation Methods and Computational Detailsmentioning

confidence: 99%

Polymer−Clay Nanocomposites: A Multiscale Molecular Modeling Approach

et al. 2007

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A hierarchical procedure bridging the gap between atomistic and mesoscopic simulation for polymer-clay nanocomposite (PCN) design is presented. The dissipative particle dynamics (DPD) is adopted as the mesoscopic simulation technique, and the interaction parameters of the mesoscopic model are estimated by mapping the corresponding energy values obtained from atomistic molecular dynamics (MD) simulations. The predicted structure of the nylon 6 PCN system considered is in excellent agreement with previous experimental and atomistic simulation results. IntroductionBlending molten polymer and inorganic clays can result in a class of new materials, in which nanoscale clay particles, generally layered silicates, are molecularly dispersed within the polymeric matrix. Such polymer-clay nanocomposites (or PCNs) exhibit dramatic increases in several properties, including mechanical strength and heat resistance, and a decrease in gas permeability when compared to the polymeric matrix alone. [1][2][3][4][5][6][7] Importantly, the improvement in these properties is achieved at very low loadings of the inorganic component, typically 1-10 wt %, thus rendering PCNs lighter in weight than any other conventionally filled polymer. These unique features make PCNs ideal materials for applications such as high barriers for food or pharmaceutical packaging to strong, heat resistant automotive components, just to name a few. Fabricating these materials in an efficient and cost-effective manner, however, poses significant synthetic challenges. To appreciate these challenges, let us discuss briefly the structure of layered silicates by considering montmorillonite (MMT) as a prime example. This inorganic clay consists of stacked silicate sheets, each approximately 200 nm long and 1 nm thick. The spacing between each sheet (or gallery) is also of the order of 1 nm, and this quantity is clearly smaller than the average radius of gyration of any conventional polymer. Therefore, entropy generally constitutes a large barrier that prevents the polymer from penetrating these galleries and becoming an intercalated material. Accordingly, there is a number of critical issues that need to be addressed in order to optimize the design and production of PCNs. Of foremost importance is the isolation of the conditions that result in a promotion of the polymer penetration into the narrow clay galleries. If, however, the sheets ultimately phase-separate from the polymer matrix, the mixture will not exhibit the improved strength, heat resistance, or barrier properties mentioned above. Accordingly, it is also essential to determine the factors that control the macroscopic phase behavior of the mixture. Finally, the properties of the PCNs commonly depend on the structure of the material; thus, it is of particular interest to establish the morphology of the final composite.

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Section: Simulation Methods and Computational Detailsmentioning

confidence: 99%

Polymer−Clay Nanocomposites: A Multiscale Molecular Modeling Approach

et al. 2007

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“…Additional details about computational methodology and simulation procedure can be found in our earlier work. 23,24 MODEL CONSTRUCTION…”

Section: Computational Methodologymentioning

confidence: 99%

“…In our earlier work, 23 a representative intercalated model of PCN containing PA6 as polymer, 12-aminolauric acid as organic modifier, and MMT as clay was constructed. In a separate work, 24 using that representative model of intercalated PCN, interaction between the different constituents of a PCN was evaluated.…”

Section: Introductionmentioning

confidence: 99%

The role of interfacial interactions on the crystallinity and nanomechanical properties of clay–polymer nanocomposites: A molecular dynamics study

Sikdar

Katti

2007

J of Applied Polymer Sci

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Polymer clay nanocomposites (PCN) show enhanced mechanical, thermal, liquid or gas barrier properties in comparison to pure polymer. However, the mechanisms for enhancement of these physical properties of PCN are not well understood. This knowledge is important for tailoring the properties of PCN to desired specifications. Our earlier study showed that organic modifiers have significant influence on the crystallinity and nanomechanical properties of PCN. For quantitative evaluation of the influence of organic modifiers on the crystallinity and nanomechanical properties of PCN, molecular models of three intercalated PCNs containing same polymer and clay but with three different organic modifiers are constructed in this work. Using molecular dynamics simulations, the interaction energies among the different constituents of PCNs are evaluated. This study reveals that the interactions between polymer, organic modifiers, and intercalated clay are critical factors in controlling the crystallinity and enhancement of nanomechanical properties of PCN. We have described the possible mechanisms leading to change in crystallinity and nanomechanical properties.

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“…However, the intermolecular interactions among ammonium salt/PP-g-MA/polymer matrix are much weaker due to only the presence of van der Waals and dipole-induced dipole force [4,16]. Therefore, the presence of PP-g-MA may interact with the clay surface through hydrogen and/or covalent bonding and that helps the dispersion of the clay in the polymer matrix [16]. Note XRD pattern of OMMT used in the present study possesses three characteristic reflection peaks at 2θ02.5, 4.3, and 7.2 corresponding to the d-spacing of 3.40, 2.10 and 1.27 nm, respectively.…”

Section: Ftir Analysismentioning

confidence: 99%

Thermal decomposition behavior and mechanical properties of elastomeric composites based on polyolefinic thermoplastic elastomer and organomontmorillonite

Saikrasun

Amornsakchai

2011

J Polym Res

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The elastomeric composites based on organomontmorillonite (OMMT) and Santoprene thermoplastic elastomer were prepared by melt processing. Maleic anhydride grafted polypropylene (PP-g-MA) was used as a compatibilizer for the composite system. By adding optimum content of PP-g-MA, the fracture surface of the composites observed by SEM was smoothened as a result from compatibilizing effect. From XRD results, the measured d-spacing data proved a good dispersion of nanoclay along with compatibilizer. Thermal decomposition behavior of the neat components and its composites obtained from simultaneous TG and DSC profiles indicated that the incorporation of OMMT into the matrix polymer improved the thermal stability in air but not in nitrogen. No significant change in thermal stability of the composites with addition of PP-g-MA. The incorporation of clay significantly enhanced in dynamic mechanical and tensile properties of the composites. The dynamic storage modulus, tensile modulus and yield stress of the composites with the presence of PP-g-MA were remarkably improved.

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Insight into molecular interactions between constituents in polymer clay nanocomposites

Cited by 64 publications

References 60 publications

Polymer−Clay Nanocomposites: A Multiscale Molecular Modeling Approach

Polymer−Clay Nanocomposites: A Multiscale Molecular Modeling Approach

The role of interfacial interactions on the crystallinity and nanomechanical properties of clay–polymer nanocomposites: A molecular dynamics study

Thermal decomposition behavior and mechanical properties of elastomeric composites based on polyolefinic thermoplastic elastomer and organomontmorillonite

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