Understanding the microstructure of particle dispersion in confined copolymer nanocomposites

Abstract

The microstructures of diblock copolymer/particle composites confined in slitpores have been investigated using a density functional theory approach. It has been shown that, under the condition of confinement, particles display different distributions near the solid surfaces, in the microdomains of two blocks, and at the microphase interfaces. The final dispersion depends on the balance between the enthalpic contribution arising from the particle-segment attraction as well as the entropy-driven depletion attraction induced by the polymer conformation and the confinement environment. For the systems in which particles weakly attract one block but repel another block, particle dispersion can be enhanced by the increasing confinement effect, and the enhancement becomes more obvious as the size asymmetries of particles and two blocks increase. If the attraction increases, however, particle dispersion declines as the confinement effect increases.

Polymer nanocomposites: Why their mechanical performance does not justify the expectation and a possible solution to the problem?

“…For the systems in which particles weakly attract one block but repel another block, particle dispersion can be enhanced by the increasing confinement effect, and the enhancement becomes more evident as the size asymmetries of particles and two blocks increase. If the attraction increases, however, particle dispersion declines as the confinement effect increases [146]. At the same time, as stated in the same publication [146], confinement induced particle dispersion in copolymer films is far from being understood.…”

“…If the attraction increases, however, particle dispersion declines as the confinement effect increases [146]. At the same time, as stated in the same publication [146], confinement induced particle dispersion in copolymer films is far from being understood. For a confined copolymer nanocomposite, because of the microphase separation of the copolymer and the physically confined environment, the state of particle dispersion becomes more complex [146].…”

“…At the same time, as stated in the same publication [146], confinement induced particle dispersion in copolymer films is far from being understood. For a confined copolymer nanocomposite, because of the microphase separation of the copolymer and the physically confined environment, the state of particle dispersion becomes more complex [146]. In the attempts for synthetic modification of particle interfaces, the emulsion polymerization is the most widely used synthetic technique [147].…”

“…Nowadays it is well recognized that the mixing of polymers and nanoparticles is paving the way for engineering flexible composites that exhibit advantageous electrical, optical, or mechanical properties [145]. In a study on understanding the microstructure of particle dispersion in confined copolymer nanocomposites [146] it has been shown that, under the condition of confinement, particles display different distributions near the solid surfaces, in the microdomains of two blocks, and at the microphase interfaces. The final dispersion depends on the balance between the enthalpic contribution arising from the particle-segment attraction as well as the entropydriven depletion attraction induced by the polymer conformation and the confinement environment.…”

Evaluation of Nanoparticle Effect on Bubble Nucleation in Polymer Foaming

“…In this work, we apply a density functional theory (DFT) approach to study the thermodynamic behaviors of homogeneous and heterogeneous nucleation of CO 2 bubbles in foaming of polystyrene (PS) and poly­(methyl methacrylate) (PMMA). DFT is an inhomogeneous theory and has achieved good performance in polymer nanocomposites. − Within the theoretical framework, the bubble nucleation occurs in the actual nanocomposite environment, involving the local supersaturation of dissolved CO 2 and subsaturation of polymer matrix, as well as the interfacial tensions of bubble–melt–particle three-phase contact. The morphology of the nucleated bubble and the density profiles inside and outside the bubble can be determined by minimizing the grand potential of the system.…”