Spin-coating of micron-scale thick PMMA films with embedded Au nanoparticles formed by laser ablation in liquid.

Background: A Facile is a scalable approach to fabricating organic thin films with an embedded layer of nanoparticles in the ambient environment. The approach is based on step-by-step spin-coating of polymethylmethacrylate (PMMA) films and a nanoparticle layer. Objective: The goal of the present work is to fabricate a sandwich structure of the PMMA films for the top and bottom layers of a sandwich structure as well as a middle layer of nanoparticles formed in solution by the laser ablation in liquid (LAL) method. Methods: First, a PMMA thin film was fabricated by spin-casting of PMMA solution in ethyl acetate. Secondly, a solution of Au nanoparticles synthesized by laser ablation in ethanol was spin-cast on a prefabricated PMMA film. The distribution of Au nanoparticles and the morphology of the resulting film were analyzed using scanning electron microscopy (SEM), optical microscopy, and atomic microscopy (AFM). Finally, another PMMA layer was spin-cast on the nanoparticle-decorated film. Results: A hybrid organic film with the embedded layer of nanoparticles was fabricated using the spin-casting method for top and bottom layers and the middle layer of Au nanoparticles fabricated by laser ablation in ethanol by a pulsed UV laser. Statistical and fractal analysis shows uniform distribution of nanoparticles on a length scale above ten microns. Conclusion: Spin-cast-based layer-by-layer approach to fabricating sandwich structures of organic films with embedded nanoparticles is a facile and scalable method for hybrid organic – nanoparticle films. This approach can be extended for the fabrication of multi-layered hybrid structures.

Iron (II) Metallo-Supramolecular Polymers Based on Thieno[3,2-b]thiophene for Electrochromic Applications

Four new bis(tpy) unimers with different linkers between the thieno[3,2-b]thiophene-2,5-diyl central unit and terpyridine-4′-yl (tpy) end-groups: no linker (Tt), ethynediyl (TtE), 1,4-phenylene (TtPh) and 2,2′-bithophene-5,5′-diyl (TtB) are prepared, characterized, and assembled with Fe2+ ions to metallo-supramolecular polymers (Fe-MSPs). The Fe-MSP films prepared by spin-casting on Indium Tin Oxide (ITO) glass are characterized by atomic force microscope (AFM) microscopy, cyclic voltammetry, and UV/vis spectroscopy and studied for their electrochromism and effect of the unimer structure on their electrochromic performance. Of the studied MSPs, Fe-Tt shows the highest optical contrast as well as coloration efficiency (CE = 641 cm2 C−1) and the fastest optical response. This makes it an excellent candidate for possible use in electrochromic devices.

Impact of the process conditions on polymer pattern morphology during spin coating over topological surfaces

Polymer phase separation of a binary system over prepatterned substrate topography during spin casting.

Biomemristic Behavior for Water-Soluble Chitosan Blended with Graphene Quantum Dot Nanocomposite

Bionanocomposite has promising biomemristic behaviors for data storage inspired by a natural biomaterial matrix. Carboxylated chitosan (CCS), a water-soluble derivative of chitosan avoiding the acidic salt removal, has better biodegradability and bioactivity, and is able to absorb graphene quantum dots (GQDs) employed as charge-trapping centers. In this investigation, biomemristic devices based on water-soluble CCS:GQDs nanocomposites were successfully achieved with the aid of the spin-casting method. The promotion of binary biomemristic behaviors for Ni/CCS:GQDs/indium-tin-oxide (ITO) was evaluated for distinct weight ratios of the chemical components. Fourier transform infrared spectroscopy, Raman spectroscopy (temperature dependence), thermogravimetric analyses and scanning electron microscopy were performed to assess the nature of the CCS:GQDs nanocomposites. The fitting curves on the experimental data further confirmed that the conduction mechanism might be attributed to charge trapping–detrapping in the CCS:GQDs nanocomposite film. Advances in water-soluble CCS-based electronic devices would open new avenues in the biocompatibility and integration of high-performance biointegrated electronics.