scholarly journals Investigation of Silicon Nanoparticle-Polystyrene Hybrids

2019 ◽  
Vol 2 (2) ◽  
pp. 49-50
Author(s):  
Madihah Khan ◽  
Alyxandra Thiessen ◽  
I Teng Cheong ◽  
Sarah Milliken ◽  
Jonathan G. C. Veinot
Keyword(s):  
Silicon Nanoparticles ◽  
In Situ Polymerization ◽  
Toxic Substance ◽  
Homogeneous Mixture ◽  
Silicon Nanoparticle ◽  
Molecular Weights ◽  
Abundant Element ◽  
The Stability ◽  
Led Lights

Current LED lights are created with quantum dots made of metals like selenium, tellurium, and cadmium which can be toxic. Silicon is used as a non-toxic substance and is the second most abundant element in the earth's crust. When silicon is prepared at a nanometer size, unique luminesce optical properties emerge that can be tuned using sized surface chemistry. Therefore, silicon nanoparticles can be used as an alternative emitter for LED lights. To produce hydride-terminated silicon nanoparticles we must synthesize the particles. Hydrogen silsesquioxane (HSQ) is processed at 1100 °C for one hour causing Si to cluster and form a SiO2 matrix, also known as the composite. The composite is then manually crushed in ethanol. The solution is further ground using glass beads, then filtered to get the composite powder. The final step is the HF etching. The hydride-terminated particles are then functionalized using three different methods to synthesize silicon nanoparticle-polystyrene hybrids, which determine the magnitude of luminosity and the quality of the hybrids. We spin coat each method and results were analyzed. Method 1 uses heat to functionalize hydride-terminated silicon nanoparticles with styrene. This process also causes styrene to attach to styrene to form a polystyrene chain. Method 1 gave a homogeneous mixture which yielded a consistent, bright and homogenous film. In method 2, dodecyl-terminated silicon nanoparticles are mixed with premade polystyrene. While this method gave better control of the amount of silicon nanoparticles inside the polymer hybrid, a homogeneous mixture was not created due to the different structures of polystyrene and dodecyl chains. Method 3 has dodecyl-terminated silicon with in-situ styrene polymerization. It generated a homogeneous mixture. The in-situ polymerization stabilizes the particles, allowing for brighter luminescence. Because of the stability and lower molecular weight, the mixture was easier to dissolve. We concluded that the different methods resulted in different polymer molecular weights and this created distinct properties between the polymer hybrids when spin-coating.    

scholarly journals PA6 and Halloysite Nanotubes Composites with Improved Hydrothermal Ageing Resistance: Role of Filler Physicochemical Properties, Functionalization and Dispersion Technique

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 211 ◽  
Author(s):  
Valentina Sabatini ◽  
Tommaso Taroni ◽  
Riccardo Rampazzo ◽  
Marco Bompieri ◽  
Daniela Maggioni ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Polymer Matrix ◽  
In Situ Polymerization ◽  
Cost Effective ◽  
Polyamide 6 ◽  
Halloysite Nanotubes ◽  
Amide Bonds ◽  
Molecular Weights ◽  
Dispersion Technique

Polyamide 6 (PA6) suffers from fast degradation in humid conditions due to hydrolysis of amide bonds, which limits its durability. The addition of nanotubular fillers represents a viable strategy for overcoming this issue, although the additive/polymer interface at high filler content can become privileged site for moisture accumulation. As a cost-effective and versatile material, halloysite nanotubes (HNT) were investigated to prepare PA6 nanocomposites with very low loadings (1–45% w/w). The roles of the physicochemical properties of two differently sourced HNT, of filler functionalization with (3-aminopropyl)triethoxysilane and of dispersion techniques (in situ polymerization vs. melt blending) were investigated. The aspect ratio (5 vs. 15) and surface charge (−31 vs. −59 mV) of the two HNT proved crucial in determining their distribution within the polymer matrix. In situ polymerization of functionalized HNT leads to enclosed and well-penetrated filler within the polymer matrix. PA6 nanocomposites crystal growth and nucleation type were studied according to Avrami theory, as well as the formation of different crystalline structures (α and γ forms). After 1680 h of ageing, functionalized HNT reduced the diffusion of water into polymer, lowering water uptake after 600 h up to 90%, increasing the materials durability also regarding molecular weights and rheological behavior.

scholarly journals Multi Self-Healable UV Shielding Polyurethane/CeO2 Protective Coating: The Effect of Low-Molecular-Weight Polyols

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1947
Author(s):  
Mohammad Mizanur Rahman ◽  
Rami Suleiman ◽  
Md. Hasan Zahir ◽  
Aasif Helal ◽  
A. Madhan Kumar ◽  
...  
Keyword(s):  
Molecular Weight ◽  
In Situ Polymerization ◽  
Outdoor Exposure ◽  
Low Molecular Weight ◽  
Self Healing ◽  
Polydimethyl Siloxane ◽  
Molecular Weights ◽  
Uv Shielding ◽  
Ceo2 Coating

We prepared a series of polyurethane (PU) coatings with defined contents using poly(tetramethylene oxide)glycol (PTMG) with two different molecular weights (i.e., Mn = 2000 and 650), as well as polydimethyl siloxane (PDMS) with a molecular weight of Mn 550. For every coating, maximum adhesive strength and excellent self-healing character (three times) were found using 6.775 mol% mixed with low-molecular-weight-based polyols (PU-11-3-3). Defined 1.0 wt% CeO2 was also used for the PU-11-3-3 coating (i.e., PU-11-3-3-CeO2) to obtain UV shielding properties. Both the in situ polymerization and blending processes were separately applied during the preparation of the PU-11-3-3-CeO2 coating dispersion. The in situ polymerization-based coating (i.e., PU-11-3-3-CeO2-P) showed similar self-healing properties. The PU-11-3-3-CeO2-P coating also showed excellent UV shielding in real outdoor exposure conditions.

scholarly journals The Use of Epoxy Silanes on Montmorillonite: An Effective Way to Improve Thermal and Rheological Properties of PLA/MMT Nanocomposites Obtained via “In Situ” Polymerization

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Valentina Sabatini ◽  
Hermes Farina ◽  
Luca Basilissi ◽  
Giuseppe Di Silvestro ◽  
Marco A. Ortenzi
Keyword(s):  
Thermal Stability ◽  
Rheological Properties ◽  
In Situ Polymerization ◽  
Rheological Behaviour ◽  
Size Exclusion ◽  
Melt Crystallization ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Exclusion Chromatography

Polylactic acid (PLA) nanocomposites were prepared via “in situ” ring opening polymerization (ROP) of lactide using a montmorillonite, Cloisite 15A, employed after surface treatment with 3-Glycidoxypropyltrimethoxysilane. The dispersion of the nanoparticles was checked using Wide Angle X-Ray Scattering (WAXS) and Transmission Electron Microscopy (TEM); both the effects of different amounts of montmorillonite and silane were measured on molecular weights and on thermal and rheological properties, using Size Exclusion Chromatography (SEC), Differential Scanning Calorimetry (DSC), thermogravimetric analyses (TGA), and rheological analyses. It was found that even very low amounts (0.1% w/w) of nanoparticles greatly affect nanocomposites properties. Unmodified montmorillonite tends to decrease molecular weights, deactivating the catalytic system used for ROP of lactide, but when epoxy silane is present molecular weights increase. Melt crystallization temperatures increase with modified nanoparticles, which enhance crystallization process. TGA analyses show that when pure montmorillonite is present, nanocomposites have lower thermal stability with respect to standard PLA; when silane is used thermal stability can get much higher than standard PLA as silane content increases. The rheological behaviour of nanocomposites shows that melt viscosity is far higher than that of standard PLA at low shear rates and also a marked shear thinning behaviour can be achieved.

The Preparation of Microcapsules Used for Self-Healing Composites

2011 ◽  
Vol 233-235 ◽  
pp. 2319-2322 ◽  
Author(s):  
Ru Tian ◽  
Yu Dong Zheng ◽  
Xin Liang ◽  
Zhang Ming Zhou ◽  
Xiao Li Fu ◽  
...  
Keyword(s):  
In Situ Polymerization ◽  
Ph Value ◽  
Condensation Reaction ◽  
Formaldehyde Resin ◽  
Self Healing ◽  
Mass Ratio ◽  
Melamine Formaldehyde ◽  
Stirring Rate ◽  
The Stability

Microcapsules were prepared by in situ polymerization of melamine-formaldehyde resin to form shell over oxygen resin droplets. Stirring rate, temperature, pH value as well as mass ratio of shell and core are the main parameters affecting the stability of microcapsules. High stirring rate leads to small size of microcapsules. The temperature influences the speed of the reaction and the morphology. The pH value decides whether the condensation reaction can take place. The size of microcapsules is about 15-61um.

Preparation and Characterization of Polypyrrole-Coated Silicon Nanoparticles

2007 ◽  
Vol 119 ◽  
pp. 295-298
Author(s):  
Hyun Shil La ◽  
Joon Pyo Jeun ◽  
Jae Hak Choi ◽  
Phil Hyun Kang ◽  
Youn Sik Lee ◽  
...  
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Silicon Nanoparticles ◽  
In Situ Polymerization ◽  
Sodium Dodecyl ◽  
Average Thickness ◽  
Si Nanoparticles ◽  
Dodecyl Sulfate ◽  
Discharge Capacities

Silicon (Si) nanoparticles were stabilized by sodium dodecyl sulfate and poly(Nvinylpyrrolidone) in water, and coated with polypyrrole (PPy) via an in-situ polymerization of pyrrole with FeCl3. TEM images revealed that the Si nanoparticles were successfully coated with PPy (average thickness, ~2 nm). The Li/PPy-coated Si electrode exhibited improved discharge capacities, when compared to that of a reported Li/pure Si electrode. PPy-coatings on the Si nanoparticles acted as efficient conducting agents and prevented an extraction of the cracked Si fragments into the electrolyte to some extent.

scholarly journals Low—Permittivity Copolymerized Polyimides with Fluorene Rigid Conjugated Structure

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6266
Author(s):  
Xiaodi Dong ◽  
Mingsheng Zheng ◽  
Baoquan Wan ◽  
Xuejie Liu ◽  
Haiping Xu ◽  
...  
Keyword(s):  
In Situ Polymerization ◽  
Signal Propagation ◽  
Dielectric Materials ◽  
Propagation Delay ◽  
Decomposition Temperature ◽  
Thermal Decomposition Temperature ◽  
Molecular Weights ◽  
Low Permittivity ◽  
Crosstalk Signal

As the miniaturization of electronic appliances and microprocessors progresses, low-permittivity interlayer materials are becoming increasingly important for their suppression of electronic crosstalk, signal propagation delay and loss, and so forth. Herein, a kind of copolyimide (CPI) film with a “fluorene” rigid conjugated structure was prepared successfully. By introducing 9,9-Bis(3-fluoro-4-aminophenyl) fluorene as the rigid conjugated structure monomer, a series of CPI films with different molecular weights were fabricated by in situ polymerization, which not only achieved the reduction of permittivity but also maintained excellent thermodynamic stability. Moreover, the hydrophobicity of the CPI film was also improved with the increasing conjugated structure fraction. The lowest permittivity reached 2.53 at 106 Hz, while the thermal decomposition temperature (Td5%) was up to 530 °C, and the tensile strength was ≥ 96 MPa. Thus, the CPI films are potential dielectric materials for microelectronic and insulation applications.

scholarly journals Design, Preparation and Thermal Characterization of Polystyrene Composites Reinforced with Novel Three-Cages POSS Molecules

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 2967
Author(s):  
Ignazio Blanco ◽  
Francesco Agatino Bottino ◽  
Gianluca Cicala ◽  
Giulia Ognibene ◽  
Claudio Tosto
Keyword(s):  
1H Nmr Spectroscopy ◽  
In Situ Polymerization ◽  
Thermal Characterization ◽  
Scanning Calorimetry ◽  
Single Cage ◽  
The Stability ◽  
First Time ◽  
Thermal Stability Of

Novel polystyrene (PS)/polyhedral oligomeric silsequioxanes (POSSs) nanocomposites were designed and prepared by in situ polymerization, using, for the first time, three-cage POSS molecules. The synthesized compounds were first characterized by Fourier transform infrared spectroscopy (FTIR) and 1H NMR spectroscopy to verify the obtaining of the designed products before their thermal performance was evaluated and compared with those of pristine PS and the corresponding single-cage POSSs nanocomposites. The thermal behaviour was checked by the means of the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) was also used to confirm the hypothesis about the dispersion/aggregation of the POSS molecules into the polymer matrix. The parameters chosen to evaluate the thermal stability of the investigated compounds, namely temperature at 5% of mass loss (T5%) and solid residue at 700 °C, showed a significant increase in the stability of the polymers reinforced with the three-cages POSS, in comparison to both PS and single-cage POSS reinforced PSs, which therefore turn out to be promising molecular fillers for nanocomposite production.

scholarly journals In-Situ Preparation of Si@C Composite Anode Materials for Lithium Ion Batteries

2014 ◽  
Vol 17 (4) ◽  
pp. 219-224
Author(s):  
Qingwei Cui ◽  
Jiang Cao ◽  
Mou Fang ◽  
Jianjun Li ◽  
Fang Lian ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Anode Materials ◽  
High Performance ◽  
Silicon Nanoparticles ◽  
In Situ Polymerization ◽  
Morphological Changes ◽  
Lithium Ion ◽  
Inert Atmosphere ◽  
Nanocomposite Material

A Si@C nanocomposite material is prepared via in-situ polymerization of acrylonitrile on the surface of silicon nanoparticles,and followed by carbonization in an inert atmosphere. The obtained Si@C nanocomposite material is composed of a nanosized Si core anda casting carbon shell. Its structure and electrochemical properties are characterized by XRD, TG, Raman, SEM, TEM and chargedischargeperformance test. The results obtained in this study show that Si@C nanocomposite is coated by a layer of amorphous carbonwhich provides a conductive matrix and relieves the dramatically morphological changes of Si upon lithium insertion and extraction. Thecomposite exhibits good capacity retention for use as anode in lithium-ion batteries. This study also paves a facile and industrial scalableway to prepare core/shell structure for high performance anode materials for lithium-ion batteries.

scholarly journals Stable Li-ion battery anodes by in-situ polymerization of conducting hydrogel to conformally coat silicon nanoparticles

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Hui Wu ◽  
Guihua Yu ◽  
Lijia Pan ◽  
Nian Liu ◽  
Matthew T. McDowell ◽  
...  
Keyword(s):  
Silicon Nanoparticles ◽  
In Situ Polymerization ◽  
Li Ion Battery ◽  
Li Ion

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

Sign in / Sign up

Export Citation Format

Share Document