scholarly journals Effect of Silica Nanoparticles Silanized by Functional/Functional or Functional/Non-Functional Silanes on the Physicochemical and Mechanical Properties of Dental Nanocomposite Resins

2021 ◽  
Vol 12 (1) ◽  
pp. 159
Author(s):  
Stefanos Karkanis ◽  
Alexandros K. Nikolaidis ◽  
Elisabeth A. Koulaouzidou ◽  
Dimitris S. Achilias
Keyword(s):  
Silica Nanoparticles ◽  
Fourier Transforms ◽  
Polymer Network ◽  
Clinical Applications ◽  
Coupling Agents ◽  
Flexural Properties ◽  
Optical Profilometry ◽  
Broad Distribution ◽  
Oral Conditions ◽  
Scanning Electron

Dental nanocomposite resins have been proposed as potential restorative materials that are inevitably challenged with dynamic oral conditions. This investigation focused on the contribution of miscellaneous silane blends, used as coupling agents, to the ultimate performance of dental nanocomposite dimethacrylate resins. Herein, silica nanoparticles were initially silanized with functional/functional or functional/non-fuctional silane mixtures (50/50 wt/wt). Fourier transforms infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) verified the modification of nanosilica. The organomodified nanoparticles were then inserted into Bis-GMA/TEGDMA based resins by hand spatulation process. Scanning electron microscopy (SEM) findings revealed a broad distribution of fillers in the polymer network when reactive silanes and their corresponding blends were used. Furthermore, optical profilometry results showed that the presence of functional/non-functional mixtures can produce relatively smooth composite surfaces. Polymerization shrinkage was found to be limited upon the decrease of the degree of conversion regarding all the tested silane mixtures. The functional/functional silane blend assured the highest flexural properties and the lowest solubility after the storage of the nanocomposite in water for 1 week at 37 °C. The above experimental data could contribute to the proper designing of dental nanocomposite resins which may fit the modern clinical applications.

scholarly journals Integration of Stable Ionic Liquid-Based Nanofluids into Polymer Membranes. Part I: Membrane Synthesis and Characterization

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 607
Author(s):  
Carolina Hermida-Merino ◽  
Fernando Pardo ◽  
Gabriel Zarca ◽  
João M. M. Araújo ◽  
Ane Urtiaga ◽  
...  
Keyword(s):  
Polymer Membranes ◽  
Small Addition ◽  
Polymeric Membranes ◽  
Synthesis And Characterization ◽  
Complete Disappearance ◽  
Optical Profilometry ◽  
Scanning Calorimetry ◽  
Exfoliated Graphene ◽  
The Stability ◽  
Scanning Electron

In this work, polymeric membranes functionalized with ionic liquids (ILs) and exfoliated graphene nanoplatelets (xGnP) were developed and characterized. These membranes based on graphene ionanofluids (IoNFs) are promising materials for gas separation. The stability of the selected IoNFs in the polymer membranes was determined by thermogravimetric analysis (TGA). The morphology of membranes was characterized using scanning electron microscope (SEM) and interferometric optical profilometry (WLOP). SEM results evidence that upon the small addition of xGnP into the IL-dominated environment, the interaction between IL and xGnP facilitates the migration of xGnP to the surface, while suppressing the interaction between IL and Pebax®1657. Fourier transform infrared spectroscopy (FTIR) was also used to determine the polymer–IoNF interactions and the distribution of the IL in the polymer matrix. Finally, the thermodynamic properties and phase transitions (polymer–IoNF) of these functionalized membranes were studied using differential scanning calorimetry (DSC). This analysis showed a gradual decrease in the melting point of the polyamide (PA6) blocks with a decrease in the corresponding melting enthalpy and a complete disappearance of the crystallinity of the polyether (PEO) phase with increasing IL content. This evidences the high compatibility and good mixing of the polymer and the IoNF.

Investigation of the Splat Deposition Behavior onto a Composite Coating in Cold Spray

2018 ◽  
Vol 941 ◽  
pp. 1639-1644
Author(s):  
Xin Chu ◽  
Phuong Vo ◽  
Stephen Yue
Keyword(s):  
Electron Microscope ◽  
Composite Coating ◽  
Cold Spray ◽  
Spray Deposition ◽  
Cold Spraying ◽  
Single Component ◽  
Optical Profilometry ◽  
Deposition Behavior ◽  
Polished Substrate ◽  
Scanning Electron

The splat test is usually generated by low feed rate cold spraying of particles onto an as-polished substrate and it can be considered as a monolayer coating deposition. In this study, in order to investigate cold spray deposition mechanisms, Fe splats were sprayed onto the cold-sprayed single component 316L, Fe, and a composite 90Fe coatings. Results showed that although there is only 3.6 vol.% of 316L in the composite 90Fe coating, Fe splats exhibit a much better deposition behavior onto the 90Fe as compared with the single component Fe coating. To explain this observation, Fe splat samples were characterized using the scanning electron microscope (SEM), optical profilometry, splat adhesion tests, and splat nanoindentation. Finally, a preliminary explanation towards the Fe splat deposition behavior onto the composite coating was drawn.

Synthesis and characterization of a novel wound dressing by PVP/ PAANa/chitosan with semi-interpenetrating polymer network structure

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Ying Wu ◽  
Qing Yang ◽  
Yali Gi ◽  
Yueting Zhang
Keyword(s):  
Network Structure ◽  
Wound Dressing ◽  
Polymer Network ◽  
Interpenetrating Polymer Network ◽  
Wound Dressings ◽  
Synthesis And Characterization ◽  
Cross Linking ◽  
Mass Ratio ◽  
Scanning Electron

AbstractA novel hydrogel wound dressing with semi-interpenetrating polymer network structure (semi-IPN) was prepared by radical polymerization of acrylic acid with potassium persulfate (K2S2O8) as initiator and N, N'-methylenebisacrylamide (MBA) as cross-linking agent in the presence of chitosan (CTS) and polyvinyl pyrrolidone (PVP). Hydrogels were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM displayed semi- IPN hydrogels' creased surface with some scale-like wrinkles, thus improving the absorptive capability which has been considered as a most important characteristic of wound dressings. It was found that the content of cross-linking agent and the mass ratio of PVP and CTS had much influence on the mechanical properties of the hydrogel, varying from brittle plastics to elastomer due to the different degrees of cross linking. Since tensile strength is partly in inverse ratio to the hydrogel absorbent capability, the article offers an analysis of varying material proportion in order to obtain an optimum properties of the hydrogel wound dressing .

UV-Blocking Properties of Silica/Titania Hybrid Nanocomposites

2007 ◽  
Vol 334-335 ◽  
pp. 1065-1068 ◽  
Author(s):  
Yi He Zhang ◽  
J.H. Xin ◽  
W.A. Daoud ◽  
Xiang Yang Hao
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Silica Nanoparticles ◽  
Field Emission ◽  
Cotton Fabric ◽  
Sol Gel ◽  
Hybrid Nanocomposites ◽  
High Magnification ◽  
Uv Blocking ◽  
Scanning Electron

Silica nanoparticles and silica/titania hybrid nanocomposites were synthesized by sol-gel processes, and padded on cotton fabric. The sizes of these particles ranged from tens to hundreds of nanometers. The morphologies of nanoparticles and hybrid nanocomposites were characterized by high magnification field-emission scanning electron microscope (FESEM). The UV-blocking properties of untreated and treated fabrics with silica/titania nanocomposites were studied and discussed.

Comparison of Tooling Materials in Injection Molding of Microscale Features

2009 ◽  
Author(s):  
Sung-Hwan Yoon ◽  
Prabhu Palanisamy ◽  
Purushotham Padmanabha ◽  
Joey L. Mead ◽  
Carol M. F. Barry
Keyword(s):  
Aspect Ratio ◽  
Injection Molding ◽  
Optical Profilometry ◽  
Free Surfaces ◽  
Polymer Hybrid ◽  
Aspect Ratios ◽  
Replication Quality ◽  
Repeated Use ◽  
Metal Polymer ◽  
Scanning Electron

Although high aspect ratio micro and nanoscale polymer features have been replicated in a range of polymers using injection molding, researchers have also used tooling inserts with a range of sizes, aspect ratios, and tooling materials. In this work, microscale features with molded in polymethylmethacrylates using three types of tooling with similar features. The tooling materials included silicon wafers with an antistiction coating, gold-coated nickel inserts, and a metal-polymer hybrid tooling. Tooling was evaluated based on the ease of melt filling and part ejection; the replication quality as characterized using optical profilometry, confocal microscopy, and scanning electron microscopy; and the damage to the tooling after repeated use. With lower aspect ratio features, the tooling type did not significantly affect replication, but for higher aspect ratio features the hybrid tooling provided far better replication than the silicon tooling. This difference was attributed to retardation of heat transfer in the features of the hybrid tooling. All three tooling materials exhibited polymer-free surfaces after injection molding.

Preparation of Polymer Microspheres Using Silane Coupling Agent Modified Nano-SiO2 as Single Stabilizer

2011 ◽  
Vol 341-342 ◽  
pp. 247-251 ◽  
Author(s):  
Guang Hui Ma ◽  
Fa Ai Zhang ◽  
Chang Sheng Gu
Keyword(s):  
Silica Nanoparticles ◽  
Average Particle Size ◽  
Optical Microscope ◽  
Coupling Agents ◽  
Average Particle ◽  
Silane Coupling Agents ◽  
Pickering Emulsion Polymerization ◽  
Silane Coupling ◽  
Unmodified Silica

This paper demonstrates that silica nanoparticles were modified by the four silane coupling agents (KH-151, KH-550, KH-560, KH-570) firstly, then polystyrene/silica (PS/SiO2) composite microsphere with PS core and silica nanoparticles shell were prepared by Pickering emulsion polymerization. The characterization of optical microscope (OM), scanning electron microscope (SEM), and thermogravimetic analysis ( TGA) illustrates that these microsphere are composed of PS and silica nanoparticles. Silica nanoparticles modified by the different silane coupling agents could form the stable PS/SiO2 microsphere over 70 °C, while the unmodified silica nanoparticles are difficult to form stable PS/SiO2 microspheres at the same temperature. The PS/KH-151-SiO2 microsphere exhibits the least average particle size, while the PS/KH-570-SiO2 microsphere produces the largest. Both SEM and TGA confirm that microsphere surface exists solid nanoparticles.

scholarly journals A novel and facile method for silica nanoparticles synthesis from high temperature vulcanization (HTV) silicon

10.30544/134 ◽  
2016 ◽  
Vol 22 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Mohammad Senemar ◽  
Ali Maleki ◽  
Behzad Niroumand ◽  
Alireza Allafchian
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silica Nanoparticles ◽  
Amorphous Silica ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Nanoparticles Synthesis ◽  
Novel Method ◽  
Scanning Electron

This study is introducing a facile and novel method for synthesis of amorphous silica nanoparticles. Silica nanoparticles were synthesized by pyrolysis and combustion of high temperature vulcanization (HTV) silicone at 700 oC for 1 h. The products were investigated employing transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS), X-ray diffraction (XRD), Brunauer Emmett and Teller (BET) test and Fourier Transform Infrared (FTIR) Spectroscopy. The results indicated that the method is capable of synthesis of amorphous silica nanoparticles with sizes of mostly between 10 and 50 nm.

scholarly journals Mapping the Distribution of Particles in Hydrogel in Use for Nanoplasmonic Biosensors: A Comparison of Preparation Methods

2018 ◽  
Author(s):  
Harald Ian Muri ◽  
Linh Hoang ◽  
Dag Roar Hjelme
Keyword(s):  
Electron Microscope ◽  
Polymer Network ◽  
Drying Methods ◽  
Preparation Methods ◽  
Particle Distributions ◽  
Imaging Parameters ◽  
Volume Imaging ◽  
Critical Point Drying ◽  
Sem Imaging ◽  
Scanning Electron

The distribution of noble metal nanoparticles in hydrogels are influencing their nanoplasmonic response and signal used for biosensor purposes. By controlling the particle distribution, it is possible to obtain new nanoplasmonic features with new sensing modalities. Particle distributions can be characterized by using volume-imaging methods such as the focused ion beam-scanning electron microscope (FIB-SEM) and the serial block-face scanning electron microscopy (SBFSEM) techniques . Since the pore structure of hydrogels is contained by the water absorbed in the polymer network it may pose challenges for volume-imaging based on electron microscope techniques since the sample must be in a vacuum chamber. The structure of hydrogels can be conserved by choosing appropriate preparation methods, which also depends on the composition of the hydrogel used. In this paper, we have prepared low-weight percentage hydrogels, with and without gold nanorods (GNR) for conventional SEM imaging by using two different drying techniques; (1) the critical point drying (CPD) technique and (2) hexamethyldisilazane (HMDS) drying of hydrogels. A qualitative characterization of the GNR-hydrogels was carried out to study the GNRs positioned in the polymer network. The effect of the two different drying methods on the hydrogel morphology were also compared. The use of HMDS as an alternative to the CPD has several advantages involving less parametrical variables for drying, involving less effort, being cost-effective, and requires no equipment use. In addition, choosing an optimized sample preparation method for SEM with optimized imaging parameters is highly important for obtaining accurate information about materials that is not correlated to artifacts. Hence, the results obtained from the preparation methods and SEM imaging parameters in this paper are useful for developing methods for mapping the metal particle distributions in micro-hydrogels by using FIB-SEM and SBFSEM techniques.

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