Phys.org February 4, 2022
To overcome a longstanding problem of molecular impurities in nanoscience a team of researchers in the US (MIT, UC Berkeley, Argonne National Laboratory) developed a new technique that coaxes diverse blends of polymers and nanoparticles into spontaneously forming tiny, nested rings within minutes of adding an impurity. They hypothesized that diversifying the blend’s composition can overcome these limitations. Increasing the number of components increases mixing entropy, leading to the dispersion of different components and, as a result, enhances interphase miscibility. The molecular migration would unlock the system’s entropy that helps to distribute the material’s building blocks, and drive the inorganic nanoparticles to organize into a series of concentric rings. To test their hypothesis, they mixed 14 different composite blends containing iron oxide and oleic acid nanoparticles, a block-copolymer-based supramolecule, small organic molecules, and silica particles coated with tiny polystyrene brushes. Through experiments they proved that nanocomposite blends containing four or more components of various sizes and chemistries can accommodate impurities. According to the researchers their study demonstrates that entropy-driven behaviors can be realized in systems beyond high-entropy alloys despite inherent differences between metal alloys and organic/inorganic hybrids…read more. TECHNICAL ARTICLE  1 , 2
Illustration of small organic molecules, block copolymer-based supramolecules, and inorganic nanoparticles… Credit: ACS Nano 2021, 15, 9, 14095–14104, July 29, 2021Â