Tailored inclusion of semiconductor nanoparticles in nanoporous polystyrene-block-polymethyl methacrylate thin films (original) (raw)
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Engineered nanoporous and nanostructured films
Materials Today, 2009
Engineered nanoporous and nanostructured films Nanoporous and nanostructured films and surfaces have been exploited by nature to spectacular effect. Plant leaves use nanostructured surfaces to shed water 1, 2 as shown in Fig. 1 and the Namib desert beetle uses a similar surface to collect water from dew 3, 4. Butterflies have fashioned nanostructured surfaces to attract mates, deter predators, and provide camouflage 5, 6 (Fig. 2). Geckos 7, 8 , flies, and other insects 9 use nanostructured surfaces to adhere to walls (Fig. 3), and all cell membranes can be thought of as sophisticated nanoporous films 10. The development of nanoporous or nanostructured thin films is relatively recent and has been driven by the need for low dielectric constant materials in the semiconductor industry 11-15 , the need for low refractive index materials in the photonics industry 16-20 , the need for nearly blackbody absorptivity in the solar cell industry 21 , the need for nanoporous membranes in the gas separations industry 22 , the need for superhydrophobic or superoleophobic materials to control wetting and spreading 23, 24 , and the general need for thin film catalytic and separations processes in the fuel cell 25, 26 , and biotechnology 27, 28 fields. Since the range Nanoporous and nanostructured films have become increasingly important to the microelectronics and photonics industries. They provide a route to low dielectric constant materials that will enable future generations of powerful microprocessors. They are the only route to achieving materials with refractive indices less than 1.2, a key feature for the future development of photonic crystal devices, enhanced omnidirectional reflectors, enhanced anti-reflection coatings and black-body absorbers. In addition, these films exhibit tremendous potential for separations, catalytic, biomedical and heat transfer applications. This article will review two primary techniques for manufacturing these films, evaporation induced self-assembly and oblique or glancing angle deposition, and will discuss some of the film properties critical to their use in the microelectronics and photonics industries.
Porous polymer nanoparticle layers
Desalination, 2009
Multilayers of colloidal polymer particles provide micro-or mesopores and can be used as a separation media similar to micro-and ultrafiltration membranes. Materials derived from polymer particles are of interest for making novel functional membranes, because they combine mesoporosity, high specific surface area and the possibility to apply functional groups on the outer and inner surface of the separation layer.
Chemistry of Materials, 1999
A poly(tert-butyl acrylate)-block-poly(2-cinnamoylethyl methacrylate), PtBA-b-PCEMA, sample was synthesized and characterized. After annealing at 105 (2°C, the PtBA block formed densely packed cylinders inside the PCEMA matrix. Thin films of the diblock were obtained by microtomy. After PCEMA photo-cross-linking, the tert-butyl groups of PtBA were hydrolyzed, leaving poly(acrylic acid) chains in the loosely packed nanometer-sized cylinders. The permeability of water across such films varied by several orders of magnitude, depending on the pH of the aqueous medium or the types of cations in it. The possibility of using such nanochannels as templates for making further nanostructures was tested by filling the nanochannels with CdS or Fe 2 O 3 nanoparticles.
International Journal of Molecular Sciences, 2013
Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS) nanoparticles (NPs) on Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH) 2 , was studied using dip-and spin-coating techniques. By dip-coating, two dimensional (2-D), randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH) 2 and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center). On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH) 2 . Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate.
Patterning Semiconductor Nanocrystals in Polymer Films
Advanced Functional Materials, 2007
This paper reports a method of patterning semiconductor nanocrystals (NCs) in a polymer film. By combining lithographic concept with polymerization-induced phase separation in a NC-monomer mixture, we produced topographic and lateral compositional patterns in NC-polymer films. The quality of the patterns was controlled by the competition between the rate of polymerization-induced phase separation and the change in viscosity of the polymerizing mixture.
Chemical engineering transactions, 2021
As the advantageous properties of nanoparticles (NPs) often emerge only when appropriate coupling and exchange phenomena between the NPs can take place, the control of the inter-particle distance, regular ordering, and location of the nanoparticles onto solid supports is a critical issue. A robust method to control the spatial organization of NPs onto solid supports, based on the use of self-assembling di-block copolymers (BCPs) as structure-guiding material, is reported. Two different polystyrene-b-poly(methyl methacrylate) (PSb-PMMA) BCPs, characterized by a different PS volume fraction, were used as matrices for the fabrication of nanocomposite thin films with cylindrical and lamellar morphologies controlled at the nanoscale. Selective inclusion of surface functionalized gold (Au) and zinc oxide (ZnO) NPs of appropriate size in the PS nanodomains was achieved from dispersions of the BCPs and NPs in a common solvent. The orientation of the BCPs cylinder and lamellar nanodomains in spin-coated thin films was controlled by solvent and thermal annealing protocols, coupled with techniques of surface neutralization.
Polymers
Nanocomposite polymer films are a very diverse research field due to their many applications. The search for low-cost, versatile methods, producing regulated properties of the final products, has thus become extremely relevant. We have previously reported a bulk-scale process, dispersing granulated metal oxide nanoparticles, of both unary and multi-component nature, in a low-density polyethylene (LDPE) polymer matrix, establishing a reference in the produced films’ optical properties, due to the high degree of homogeneity and preservation of the primary particle size allowed by this method. In this work, unmodified, free-standing particles, namely zinc oxide (ZnO), titanium dioxide (TiO2), aluminum oxide (Al2O3), and silicon dioxide (SiO2) are blended directly with LDPE, and the optical properties of the fabricated films are compared to those of films made using the granulation process. The direct blending process evidently allows for control of the secondary particle size and ensur...