On the parameters influencing the deposition of polystyrene colloidal crystals (original) (raw)
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Journal of Dispersion Science and Technology, 2019
This research describes a one-step procedure for monodispersed poly(styrene-methyl-methacrylateacrylic acid colloidal spheres [P(St-MMA-AA)] via soap-seeded emulsion polymerization. The effects ofreaction conditions such as temperature, stirring speed, initiation concentration, e.t.c. were examined. The results obtained showed that the spheres average particle diameter decreased with increase in initiator concentration, the reaction temperature and stirring speed and increased with an increase in monomer concentrations. The particles show stable mechanical properties within the transition and heating temperatures of 111.9 C and 388 C respectively. Zeta-potential values ranging from À31.8 mV to À36.5 mV which is indicative of stable dispersion of colloidal particles were obtained for all the prepared latexes. The assembled colloidal latex had periodic structures with mainly hexagonal three-dimensional structures with multi-facet arrangements. The latex also shows spherical shape of monodispersed core-shell particles.
Applied Surface Science, 2018
In this paper, it is shown that the concentration of the colloidal suspension has a significant role in the assembly of a uniform centimeter-sized Monolayer Colloidal Crystal (MCC) and the optimized range of the concentrations for fabricating MCCs made of polystyrene (PS) microspheres with the diameter of 508 nm is obtained. The gravity assisted convective assembly method is used to fabricate MCCs. It has been shown that not only the size of the MCC but also its uniformity and quality is highly dependent on the concentration of the colloidal suspension. Having used different methods to analyze the samples such as taking the transmission spectra, optical microscopy imaging, scanning electron microscopy (SEM) imaging, and studying the diffraction patterns of the samples, it is deduced that the optimized range of the concentration is from 1.7 wt% to 1.85 wt%.
Construction of Mono- and Multilayer Colloidal Crystals with Self-Assembled Nanospheres
Journal of Nanoscience and Nanotechnology, 2013
A new self-assembly method for the fabrication of periodic structures using monodispersed polystyrene nanoparticles matrix was developed. The self-assembly could be formed into polystyrene nanoparticles matrix constructed by the face centered cubic (FCC) structure and hexagonally close-packed (HCP) monolayer. The polystyrene nanoparticles have been prepared by emulsion polymerization. Several aspects were investigated by using different techniques: Particle sizer, TEM and DSC etc. In this study, the feasibility of synthesizing nanoparticles of 550 nm polystyrene with a perfect spherical shape and a narrow size distribution was demonstrated. Subsequently, an investigation of the self-assembly of polystyrene nanospheres to built up an opal structure was performed. This arrangement was achieved by gravitational sedimentation under vacuum. The face centered cubic structure was identified by using SEM, thus that the different facet type {100}, {110} and {111} were composed. The self-assembly of monodispersed polystyrene nanoparticles in 2D structure was fabricated in the structure of hexagonally close-packed monolayer.
Size control of highly monodisperse polystyrene particles by modified dispersion polymerization
Macromolecular Research, 2010
Highly monodisperse polystyrene (PS) particles have been synthesized by modified dispersion polymerization in which aqueous alcohols, polyvinylpyrrolidone (PVP), and ammonium persulfate (APS) are used as a medium, steric stabilizer, and initiator, respectively. An ionic initiator, APS, in typical dispersion polymerization would help stabilize the growing PS particles by electrical repulsion, resulting in a monodisperse particle size distribution. Moreover, the dual functions of APS as an initiator and electric stabilizer compete to determine the final size of the PS particles and lead the size of PS particles to be less sensitive to the APS concentration. Therefore, it was possible to control precisely the size of highly monodisperse PS particles in the diameter range, 800 to 2,000 nm. In addition, the highly monodisperse PS particles below 800 nm in size could be obtained just by quenching the reactant with time. Therefore, these PS particles can be used readily to fabricate colloidal crystals owing to their high monodispersity.
2010-Dry etching of colloidal crystal films.pdf
Two types of non-close-packed colloidal crystal films were prepared by etching the films made of polystyrene nanospheres using a hyperthermal neutral beam of oxygen gas. Etching without sintering above glass transition temperature of the polymer particles resulted in the non-close-packed structure of the nanospheres, in which polystyrene nanospheres in different lattice planes touched each other due to the reduction in the size of the nanospheres that occurred during the etching process. In contrast, a different non-close-packed structure with inter-connecting networks between etched nanospheres was generated by annealing of the colloidal crystal and a subsequent etching process. The photonic bandgap could be tuned during this dry etching of colloidal photonic crystals. This connected open structure could be used as a template for a silica inverse opal by chemical vapor deposition. An alternative dry etching process, reactive ion etching, mainly affected the morphology of particles near the top surface, and only a slight change in the stop band position of the colloidal crystal film was observed.
Colloidal Crystallization As Compared with Polymer Crystallization
Polymer Journal, 2008
Recent work made in the author's laboratory on the morphology (especially, giant colloidal crystals), crystal structure, fundamental properties such as phase transition, light-scattering, viscosity and elasticity, crystallization kinetics and electrooptics of colloidal crystals have been reviewed. Colloidal crystals are really crystal as typical other crystals, metals, polymers and ice, for example. However, the inter-particle force of colloidal crystal is ''repulsion'' exclusively and being different from the other typical crystals, where the inter-particle ''attraction'' plays an important role for crystallization. It is pointed out that the apparent ''attraction'' is induced inevitably for the colloidal crystallization in a closed vessel.
Proceedings of 2004 6th International Conference on Transparent Optical Networks (IEEE Cat. No.04EX804)
Self-assembled methods for the preparation of inverted opals is nowadays an important way to obtain 3D photonic crystals, since they offer some advantages as important as reduced costs. The main drawback of these techniques is the domain size achieved. We report a novel method of colloidal particles arrangement which reduces the formation of defects and increases the domain sizes. This method consists on assisting, by a von Kármán-like flow, the electrophoretic deposition of polystyrene particles. In this paper we study the effects caused by the application of such flow.
Dry etching of colloidal crystal films
Journal of Colloid and Interface Science, 2010
Two types of non-close-packed colloidal crystal films were prepared by etching the films made of polystyrene nanospheres using a hyperthermal neutral beam of oxygen gas. Etching without sintering above glass transition temperature of the polymer particles resulted in the non-close-packed structure of the nanospheres, in which polystyrene nanospheres in different lattice planes touched each other due to the reduction in the size of the nanospheres that occurred during the etching process. In contrast, a different non-close-packed structure with interconnecting networks between etched nanospheres was generated by annealing of the colloidal crystal and a subsequent etching process. The photonic bandgap could be tuned during this dry etching of colloidal photonic crystals. This connected open structure could be used as a template for a silica inverse opal by chemical vapor deposition. An alternative dry etching process, reactive ion etching, mainly affected the morphology of particles near the top surface, and only a slight change in the stop band position of the colloidal crystal film was observed.
Poly(styrene-hydroxyethyl methacrylate) [P(ST-HEMA)] latex particles were prepared by surfactant-free emulsion copolymerization. As water-soluble initiator was used potassium persulfate (KPS). The influence of different reactions parameters, such as the reaction temperature, the both monomers (ST and HEMA) concentrations and the KPS concentration on the particles average diameter and particles size dispersion was investigated. Generally monodisperse spherical particles are synthesized, but we also obtained stable large three-dimensional colloidal aggregates. These are formed by the agglomeration of monodispersed spheres in certain polymerization conditions. The P(ST-HEMA) monodispersed spheres with 350 nm average diameter were assembled into colloidal crystals using dip-coating technique. Colloidal crystals with different thickness were obtained by modifying two experimental factors, the colloidal concentration and the substrate lifting speed. The morphologies of copolymer latex particles and colloidal crystals were observed using scanning electron microscopy (SEM). The optical properties of colloidal crystals films were also investigated by transmission spectroscopy.