In Situ Self Assembly of Nanocomposites: Competition of Chaotic Advection and Interfacial Effects as Observed by X-Ray Diffreaction

• Published in: Nanomaterials (Basel, Switzerland) Vol. 5; no. 1; pp. 351 - 365
• Main Authors: Ratnaweera, Dilru R, Mahesha, Chaitra, Zumbrunnen, David A, Perahia, Dvora
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 17-03-2015; MDPI
• Subjects: Advection; Assembly; Chaos theory; chaotic advection; Crystal structure; Nanocomposites; Nanomaterials; Nanoparticles; nylon; Polymer blends; Polymers; Process parameters; Self assembly; smart blending; Transmission electron microscopy; Vortices; X-ray diffraction; X-rays; United States > US; X-ray diffraction; assembly; chaotic advection; smart blending; nanocomposites; nylon
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano5010351

The effects of chaotic advection on the
assembly of a hierarchal nanocomposite of Poly Amide 6, (nylon 6 or PA6) and platelet shape nanoparticles (NPs) were studied. The assemblies were formed by chaotic advection, where melts of pristine PA6 and a mixture of PA6 with NPs were segregated into discrete layers and extruded into film in a continuous process. The process assembles the nanocomposite into alternating pristine-polymer and oriented NP/polymer layers. The structure of these hierarchal assemblies was probed by X-rays as a processing parameter, N, was varied. This parameter provides a measure of the extent of
structuring by chaotic advection. We found that all assemblies are semi-crystalline at room temperature. Increasing N impacts the ratio of α to γ crystalline forms. The effects of the chaotic advection vary with the concentration of the NPs. For nanocomposites with lower NP concentrations the amount of the γ crystalline form increased with N. However, at higher NP concentrations, interfacial effects of the NP play a significant role in determining the structure, where the NPs oriented along the melt flow direction and the polymer chains oriented perpendicular to the NP surfaces.