scholarly journals Preparation and Properties of PTFE-PMMA Core-Shell Nanoparticles and Nanocomposites

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Diego Antonioli ◽  
Michele Laus ◽  
Giampaolo Zuccheri ◽  
Valerj Kapeliouchko ◽  
Maria Cristina Righetti ◽  
...  
Keyword(s):  
Particle Size ◽  
Core Shell ◽  
Seeded Emulsion Polymerization ◽  
Shell Nanoparticles ◽  
Precise Control ◽  
Seed Particles ◽  
Wide Compositional Range ◽  
Shell Forming ◽  
Shell Particles ◽  
Core Shell Nanoparticles

The preparation of polytetrafluoroethylene-poly(methyl methacrylate) (PTFE-PMMA) core-shell particles was described, featuring controlled size and narrow size distribution over a wide compositional range, through a seeded emulsion polymerization starting from a PTFE seed of 26 nanometers. Over the entire MMA/PTFE range, the particle size increases as the MMA/PTFE ratio increases. A very precise control over the particle size can be exerted by properly adjusting the ratio between the monomer and the PTFE seed. Particles in the 80–240 nm range can be prepared with uniformity indexes suited to build 2D and 3D colloidal crystals. These core-shell particles were employed to prepare nanocomposites with different compositions, through an annealing procedure at a temperature higher than the glass transition temperature of the shell forming polymer. A perfect dispersion of the PTFE particles within the PMMA matrix was obtained and optically transparent nanocomposites were prepared containing a very high PTFE amount.

scholarly journals Synthesis and Advanced Characterization of Polymer-Protein Core-Shell Nanoparticles

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 730
Author(s):  
Erik Sarnello ◽  
Tao Li
Keyword(s):  
Particle Size ◽  
Small Angle ◽  
Core Shell ◽  
Assembly Process ◽  
Shell Nanoparticles ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
Core Shell Nanoparticles ◽  
Ray Scattering

Enzyme immobilization techniques are widely researched due to their wide range of applications. Polymer–protein core–shell nanoparticles (CSNPs) have emerged as a promising technique for enzyme/protein immobilization via a self-assembly process. Based on the desired application, different sizes and distribution of the polymer–protein CSNPs may be required. This work systematically studies the assembly process of poly(4-vinyl pyridine) and bovine serum albumin CSNPs. Average particle size was controlled by varying the concentrations of each reagent. Particle size and size distributions were monitored by dynamic light scattering, ultra-small-angle X-ray scattering, small-angle X-ray scattering and transmission electron microscopy. Results showed a wide range of CSNPs could be assembled ranging from an average radius as small as 52.3 nm, to particles above 1 µm by adjusting reagent concentrations. In situ X-ray scattering techniques monitored particle assembly as a function of time showing the initial particle growth followed by a decrease in particle size as they reach equilibrium. The results outline a general strategy that can be applied to other CSNP systems to better control particle size and distribution for various applications.

Identification of aggregates of magnetic nanoparticles in ferrofluids at low concentrations

2003 ◽  
Vol 36 (4) ◽  
pp. 1069-1074 ◽  
Author(s):  
D. Eberbeck ◽  
A. Lange ◽  
M. Hentschel
Keyword(s):  
Magnetic Nanoparticles ◽  
Radial Distance ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Core Diameter ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Dilute Suspensions ◽  
Shell Particles ◽  
Core Shell Nanoparticles

Different very dilute suspensions of magnetic nanoparticles (magnetite surrounded by an organic shell) in water (ferrofluids) were investigated using small-angle X-ray scattering. It is shown that the scattering originates not only from noncorrelated core–shell nanoparticles, but also from larger structures. By modelling, these structures can be identified as close-packed clusters consisting of core–shell particles (core diameter ∼10 nm). The analysis of the radial distance distribution function, obtained by Fourier transformation of the scattered intensity, reveals a lower bound of the mean cluster size of about 40 nm. The formation of clusters is persistent, even in very dilute suspensions.

Monodisperse Fe3O4/Fe Core/Shell Nanoparticles with Enhanced Magnetic Property

2011 ◽  
Vol 306-307 ◽  
pp. 410-415
Author(s):  
Li Sun ◽  
Fu Tian Liu ◽  
Qi Hui Jiang ◽  
Xiu Xiu Chen ◽  
Ping Yang
Keyword(s):  
Average Diameter ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
X Ray ◽  
Transmission Electron ◽  
Shell Particles ◽  
Core Shell Nanoparticles

Core/shell type nanoparticles with an average diameter of 20nm were synthesized by chemical precipitation method. Firstly, Monodisperse Fe3O4 nanoparticles were synthesized by solvethermal method. FeSO4ž7H2O and NaBH4 were respectively dissolved in distilled water, then moderated Fe3O4 particles and surfactant(PVP) were ultrasonic dispersed into the FeSO4ž7H2O solution. The resulting solution was stirred 2 h at room temperature. Fe could be deposited on the surface of monodispersed Fe3O4 nanoparticles to form core-shell particles. The particles were characterized by using various experimental techniques, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), AGM and DTA. The results suggest that the saturation magnetization of the nanocomposites is 100 emu/g. The composition of the samples show monodisperse and the sides of the core/shell nanoparticles are 20-30nm. It is noted that the formation of Fe3O4/Fe nanocomposites magnetite nanoparticles possess superparamagnetic property.

scholarly journals Building effective core/shell polymer nanoparticles for epoxy composite toughening based on Hansen solubility parameters

2021 ◽  
Vol 10 (1) ◽  
pp. 1183-1196
Author(s):  
Na Ning ◽  
Yiping Qiu ◽  
Yi Wei
Keyword(s):  
Interfacial Interaction ◽  
Solubility Parameters ◽  
Core Shell ◽  
Hansen Solubility Parameters ◽  
Shell Nanoparticles ◽  
Shell Particle ◽  
Uniform Dispersion ◽  
Shell Particles ◽  
Core Shell Nanoparticles ◽  
Hansen Solubility

Abstract Particles have been demonstrated to toughen epoxy resins, especially for fiber-reinforced epoxy composites, and core/shell particles are one of them. It is known that not all particles toughen the same but most evaluations are through experimentation, and few studies have been conducted to accurately predict the particles’ toughening effect or guide the design of effective particles. In this study, efforts were made to find the control factors of core/shell particles, primarily interfacial compatibility and degree of dispersion, and how to predict them. Nanocomposites were fabricated by incorporating core/shell nanoparticles having various shell polymer compositions, especially their polarities. Their compatibility was estimated using a novel quantitative approach via adopting the theory of Hansen solubility parameters (HSP), in which the HSP of core/shell nanoparticles and the epoxy matrix were experimentally determined and compared. It was found that the HSP distance was a good predictor for particle dispersion and interfacial interaction. Particles having a small HSP distance (R a) to the epoxy resin, represented by the polybutylacrylate core/polymethyl methacrylate shell particle having the smallest R a of 0.50, indicated a uniform dispersion and strong interfacial bonding with the matrix and yielded outstanding toughening performance. In contrast, polybutylacrylate core/polyacrylonitrile shell particle having the largest HSP distance (6.56) formed aggregates and exhibited low interfacial interaction, leading to poor toughness. It was also demonstrated that HSP can provide an effective strategy to facilitate the design of effective core/shell nanoparticles for epoxy toughening.

scholarly journals Structural and Spectroscopic Characterization of PM 597 Dye-Silica Core-Shell Nanoparticles

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Tahani R. Al-Biladi ◽  
A. S. Al Dwayyan ◽  
M. Naziruddin Khan ◽  
Saif M. H. Qaid ◽  
Khalid Al Zahrani
Keyword(s):  
Emission Spectra ◽  
Spectroscopic Characterization ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Silica Core ◽  
Shell Particles ◽  
Average Size ◽  
Core Shell Nanoparticles ◽  
20 Nm

Nanostructured fluorescent pyrromethene (PM) doped-silica core-shell particles were successfully prepared by Stöber process. The average size of the particles was in the range of 10–20 nm measured by TEM micrograph. The atomic structure and morphology of PM 597/SiO2core/shell nanoparticles were studied by AFM and SEM, respectively. Absorption and emission spectra of the PM 597/SiO2core/shell nanoparticles under the UV irradiation were studied and not significantly influenced at the position of peaks. Finally, amplified spontaneous emission (ASE) and photobleaching of dye were examined and found no significant influence on the peaks of PM dye due to the formation of smaller sizes of PM 597/SiO2core/shell nanoparticles. The observed PM 597/SiO2core/shell nanoparticles were different in shapes with smaller size distribution and highly luminescent. Majority of nanoparticles were roughly spherical with many of them aggregated. The less photobleaching of dye core may be due to the protection of pumped energy by SiO2shell and restricts the leakage of dye.

Core–shell metal fluoride nanoparticles via fluorolytic sol–gel synthesis – a fast and efficient construction kit

2017 ◽  
Vol 5 (22) ◽  
pp. 5444-5450 ◽  
Author(s):  
B. Ritter ◽  
P. Haida ◽  
T. Krahl ◽  
G. Scholz ◽  
E. Kemnitz
Keyword(s):  
Sol Gel ◽  
Core Shell ◽  
Metal Fluoride ◽  
Shell Nanoparticles ◽  
Efficient Construction ◽  
Shell Particles ◽  
Core Shell Nanoparticles ◽  
Sol Gel Synthesis ◽  
Rare Earth Doped ◽  
Construction Kit

An efficient, fast and easy construction kit using the fluorolytic sol–gel synthesis of rare-earth-doped alkaline earth fluoride core–shell nanoparticles at room temperature is presented, capable of synthesizing several hundred grams to kilograms of core–shell particles in one batch.

scholarly journals Preparation, Properties, and Self-Assembly Behavior of PTFE-Based Core-Shell Nanospheres

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Katia Sparnacci ◽  
Diego Antonioli ◽  
Simone Deregibus ◽  
Michele Laus ◽  
Giampaolo Zuccheri ◽  
...  
Keyword(s):  
Particle Size ◽  
Self Assembly ◽  
Colloidal Crystal ◽  
Colloidal Crystals ◽  
Direct Consequence ◽  
Core Shell ◽  
Precise Control ◽  
Assembly Behavior ◽  
Shell Particles ◽  
High Degree

Nanosized PTFE-based core-shell particles can be prepared by emulsifier-free seed emulsion polymerization technique starting from spherical or rod-like PTFE seeds of different size. The shell can be constituted by the relatively high Tg polystyrene and polymethylmethacrylate as well as by low Tg polyacrylic copolymers. Peculiar thermal behavior of the PTFE component is observed due to the high degree of PTFE compartmentalization. A very precise control over the particle size can be exerted by properly adjusting the ratio between the monomers and the PTFE seed. In addition, the particle size distribution self-sharpens as the ratio monomer/PTFE increases. Samples with uniformity ratios suited to build 2D and 3D colloidal crystals are easily prepared. In particular, 2D colloidal crystal of spheres leads to very small 2D nanostructuration, useful for the preparation of masks with a combination of nanosphere lithography and reactive ion etching. 3D colloidal crystals were also obtained featuring excellent opal quality, which is a direct consequence of the monodispersity of colloids used for their growth.

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