scholarly journals Synthesis and Characterization of Polycarbonate Copolymers Containing Benzoyl Groups on the Side Chain for Scratch Resistance

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Hohyoun Jang ◽  
Jaeseong Ha ◽  
Jiho Yoo ◽  
Jaeseung Pyo ◽  
Kunyoung Choi ◽  
...  
Keyword(s):  
Methylene Chloride ◽  
Water Drop ◽  
Scratch Resistance ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
H Nmr ◽  
Chemical Structures ◽  
Atomic Force ◽  
Rearrangement Reaction ◽  
Surface Morphologies

The purpose of this study was to enhance the scratch resistance of polycarbonate copolymer by using 3,3′-dibenzoyl-4,4′-dihydroxybiphenyl (DBHP) monomer, containing benzoyl moieties on the ortho positions. DBHP monomer was synthesized from 4,4′-dihydroxybiphenyl and benzoyl chloride, followed by the Friedel-Craft rearrangement reaction with AlCl3. The polymerizations were conducted following the low-temperature procedure, which is carried out in methylene chloride by using triphosgene, triethylamine, bisphenol-A, and DBHP. The chemical structures of the polycarbonate copolymers were confirmed by1H-NMR. The thermal properties of copolymers were investigated by thermogravimetric analysis and differential scanning calorimetry, and also surface morphologies were assessed by atomic force microscopy. The scratch resistance of homopolymer film (100 μm) changed from 6B to 1B, and the contact angle of a sessile water drop onto the homopolymer film also increased.

scholarly journals Preparation, Thermal, and Thermo-Mechanical Characterization of Polymeric Blends Based on Di(meth)acrylate Monomers

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 878
Author(s):  
Krystyna Wnuczek ◽  
Andrzej Puszka ◽  
Łukasz Klapiszewski ◽  
Beata Podkościelna
Keyword(s):  
Mechanical Analysis ◽  
Attenuated Total Reflection ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Chemical Structures ◽  
Atomic Force ◽  
Polymeric Blends ◽  
Ft Ir ◽  
Acrylate Monomers ◽  
Synthesized Materials

This study presents the preparation and the thermo-mechanical characteristics of polymeric blends based on di(meth)acrylates monomers. Bisphenol A glycerolate diacrylate (BPA.GDA) or ethylene glycol dimethacrylate (EGDMA) were used as crosslinking monomers. Methyl methacrylate (MMA) was used as an active solvent in both copolymerization approaches. Commercial polycarbonate (PC) was used as a modifying soluble additive. The preparation of blends and method of polymerization by using UV initiator (Irqacure® 651) was proposed. Two parallel sets of MMA-based materials were obtained. The first included more harmless linear hydrocarbons (EGDMA + MMA), whereas the second included the usually used aromatic copolymers (BPA.GDA + MMA). The influence of different amounts of PC on the physicochemical properties was discussed in detail. Chemical structures of the copolymers were confirmed by attenuated total reflection–Fourier transform infrared (ATR/FT-IR) spectroscopy. Thermo-mechanical properties of the synthesized materials were investigated by means of differential scanning calorimetry (DSC), thermogravimetric (TG/DTG) analyses, and dynamic mechanical analysis (DMA). The hardness of the obtained materials was also tested. In order to evaluate the surface of the materials, their images were obtained with the use of atomic force microscopy (AFM).

Polysiloxanes modified with aromatic diamines interconnecting with silica network

2010 ◽  
Vol 45 (6) ◽  
pp. 621-630 ◽  
Author(s):  
Mihaela Alexandru ◽  
Carmen Racles ◽  
Maria Cazacu ◽  
Alexandra Nistor ◽  
Ana-Maria Macsim
Keyword(s):  
Sol Gel ◽  
Aromatic Diamine ◽  
Thermal Transitions ◽  
Dynamic Vapor Sorption ◽  
Silica Network ◽  
Scanning Calorimetry ◽  
Aromatic Diamines ◽  
Force Microscopy ◽  
H Nmr ◽  
Atomic Force

Polydimethylsiloxane-α,ω-diols with different contents of pendant chloromethyl groups were reacted with an aromatic diamine (3,3′-dimethoxybenzidine) when cross-linking occurred. The reactions were performed in silica — generating sol— gel system; so two interconnected networks (silica and cross-linked polydimethylsiloxane) were formed. The resulting structures were investigated by FT-IR and 1H-NMR spectroscopies. Differential scanning calorimetry was used to emphasize the thermal transitions of the resulted materials and the water sorption capacity was investigated by dynamic vapor sorption, the obtained values being influenced by the amount of polar groups. Atomic force microscopy was used to evaluate the morphology and surface topography in dry as well as in swollen state in water and heptane.

scholarly journals On-surface activation of benzylic C-H bonds for the synthesis of pentagon-fused graphene nanoribbons

Nano Research ◽  
2021 ◽  
Author(s):  
Xiushang Xu ◽  
Marco Di Giovannantonio ◽  
José I. Urgel ◽  
Carlo A. Pignedoli ◽  
Pascal Ruffieux ◽  
...  
Keyword(s):  
Carbon Nanomaterials ◽  
Graphene Nanoribbons ◽  
Gold Surface ◽  
Fine Tuning ◽  
Uniform Structure ◽  
Methyl Groups ◽  
Structural Modifications ◽  
Force Microscopy ◽  
Chemical Structures ◽  
Atomic Force

AbstractGraphene nanoribbons (GNRs) have potential for applications in electronic devices. A key issue, thereby, is the fine-tuning of their electronic characteristics, which can be achieved through subtle structural modifications. These are not limited to the conventional armchair, zigzag, and cove edges, but also possible through incorporation of non-hexagonal rings. On-surface synthesis enables the fabrication and visualization of GNRs with atomically precise chemical structures, but strategies for the incorporation of non-hexagonal rings have been underexplored. Herein, we describe the on-surface synthesis of armchair-edged GNRs with incorporated five-membered rings through the C-H activation and cyclization of benzylic methyl groups. Ortho-Tolyl-substituted dibromobianthryl was employed as the precursor monomer, and visualization of the resulting structures after annealing at 300 °C on a gold surface by high-resolution noncontact atomic force microscopy clearly revealed the formation of methylene-bridged pentagons at the GNR edges. These persisted after annealing at 340 °C, along with a few fully conjugated pentagons having singly-hydrogenated apexes. The benzylic methyl groups could also migrate or cleave-off, resulting in defects lacking the five-membered rings. Moreover, unexpected and unique structural rearrangements, including the formation of embedded heptagons, were observed. Despite the coexistence of different reaction pathways that hamper selective synthesis of a uniform structure, our results provide novel insights into on-surface reactions en route to functional, non-benzenoid carbon nanomaterials.

Mechanical Interlocking on Leadframe Surface for Bondability of Au Wedge Bond

2016 ◽  
Vol 857 ◽  
pp. 79-82
Author(s):  
Roslina Ismail ◽  
Fuaida Harun ◽  
Azman Jalar ◽  
Shahrum Abdullah
Keyword(s):  
Optical Microscope ◽  
Bonding Process ◽  
Mechanical Interlocking ◽  
Average Roughness ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Morphologies ◽  
Scanning Electron ◽  
Effect Of Surface

This work is a contribution towards the understanding of wire bond integrity and reliability in relation to their microstructural and mechanical properties in semiconductor packaging.The effect of surface roughness and hardness of leadframe on the bondability of Au wedge bond still requires detail analysis. Two type of leadframes namely leadframe A and leadframe B were chosen and scanning electron microscope (SEM) and optical microscope were used to inspect the surface morphology of leadframes and the quality of created Au wedge bond after wire bonding process. It was found that there were significant differences in the surface morphologies between these two leadframes. The atomic force microscopy (AFM) which was utilized to measure the average roughness, Ra of lead finger confirms that leadframe A has the highest Ra with value of 166.46 nm compared to that of leadframe B with value of 85.89 nm. While hardness value of different lead finger from the selected leadframe A and B obtained using Vicker microhardness tester are 180.9 VH and 154.2VH respectively.

The role of cross-linking in the scratch resistance of organic coatings: An investigation using Atomic Force Microscopy

Wear ◽  
2019 ◽  
Vol 418-419 ◽  
pp. 151-159 ◽  
Author(s):  
Juan F. Gonzalez-Martinez ◽  
Erum Kakar ◽  
Stefan Erkselius ◽  
Nicola Rehnberg ◽  
Javier Sotres
Keyword(s):  
Atomic Force Microscopy ◽  
Scratch Resistance ◽  
Organic Coatings ◽  
Cross Linking ◽  
Force Microscopy ◽  
Atomic Force

Determination of the Physical Properties of Oil Sands Components using Scanning Probe Microscopy

2015 ◽  
Vol 1754 ◽  
pp. 69-74
Author(s):  
Ravi Gaikwad ◽  
Tinu Abraham ◽  
Aharnish Hande ◽  
Fatemeh Bakhtiari ◽  
Siddhartha Das ◽  
...  
Keyword(s):  
Oil Sands ◽  
Structural Changes ◽  
Rational Approach ◽  
Kelvin Probe ◽  
Scanning Calorimetry ◽  
Probe Microscopy ◽  
Kelvin Probe Microscopy ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTAtomic force microscopy is employed to study the structural changes in the morphology and physical characteristics of asphaltene aggregates as a function of temperature. The exotic fractal structure obtained by evaporation-driven asphaltene aggregates shows an interesting dynamics for a large range of temperatures from 25°C to 80°C. The changes in the topography, surface potential and adhesion are unnoticeable until 70°C. However, a significant change in the dynamics and material properties is displayed in the range of 70°C - 80°C, during which the aspahltene aggregates acquire ‘liquid-like’ mobility and fuse together. This behaviour is attributed to the transition from the pure amorphous phase to a crystalline liquid phase which occurs at approximately 70°C as shown by using Differential Scanning Calorimetry (DSC). Additionally, the charged nature of asphaltenes and bitumen is also explored using kelvin probe microscopy. Such observations can lead to the development of a rational approach to the fundamental understanding of asphaltene aggregation dynamics and may help in devising novel techniques for the handling and separation of asphaltene aggregates using dielectrophoretic methods.

scholarly journals Atomic Force Microscopy Applied to Atopic Dermatitis Study

2021 ◽  
Vol 18 (4) ◽  
pp. 21-28
Author(s):  
Simona Maria Ţîrcă ◽  
Ion Ţîrcă ◽  
Marius Sorin Ciontea ◽  
Florin Dumitru Mihălţan
Keyword(s):  
Atomic Force Microscopy ◽  
Atopic Dermatitis ◽  
Structural Integrity ◽  
Clinical Investigation ◽  
Normal Skin ◽  
Skin Lesions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Child Patient ◽  
Surface Morphologies

Abstract Atopic dermatitis (AD)-the commonest inflammatory skin disease affects up to 25% of children and 2% to 5% of adults. Methods of the diagnostic provide expanded recommendations founded on available evidence. Morphological evaluation remains a principal feature of clinical investigation and the main criteria of diagnosis. Methods. We collected normal and affected skin from a 6-month child patient who was diagnosed through dermatologic examination. Clinical characteristics and the diagnosis of atopic dermatitis were in accordance with Hanifin and Rajka criteria. Morphology and structural integrity were investigated by Atomic Force Microscopy. Results. Optical and topography images indicate that in the case of AD skin lesions the cuticle structure was severely damaged and distorted with the flattening and grading of the plates, which have an irregular appearance. From the surface morphologies of the samples, we demonstrate that the shape of the corneocytes, with granular and elongated appearance, specific to normal skin is transformed by AD into broken and collapsed plates with discontinuous appearance. Conclusions. In the initial diagnosis of AD changes of the skin properties can be an indicator. Hanifin and Rajka criteria together with Atomic Force Microscopy can be a useful and necessary technique diagnosing cases of atopic dermatitis.

A correlation between the Wolf-Wilburn scale and atomic force microscopy for anti-scratch resistance determination

2018 ◽  
Vol 125 ◽  
pp. 325-330 ◽  
Author(s):  
Daniel Domene-López ◽  
Juan Carlos García-Quesada ◽  
Ignacio Martín-Gullón
Keyword(s):  
Atomic Force Microscopy ◽  
Scratch Resistance ◽  
Force Microscopy ◽  
Atomic Force

Physical characterization and in vitro evaluation of 3D printed hydroxyapatite, tricalcium phosphate, zirconia, alumina, and SiAlON structures made by lithographic ceramic manufacturing

MRS Advances ◽  
2020 ◽  
Vol 5 (46-47) ◽  
pp. 2419-2428
Author(s):  
Alexander K. Nguyen ◽  
Peter L. Goering ◽  
Shelby A. Skoog ◽  
Roger J. Narayan
Keyword(s):  
Tricalcium Phosphate ◽  
Force Microscopy ◽  
Atomic Force ◽  
3D Printed ◽  
Ceramic Manufacturing ◽  
Surface Morphologies ◽  
Combination Of Material ◽  
Amorphous Character ◽  
Cells Cultured

AbstractIn this study, lithographic ceramic manufacturing was used to create solid chips out of hydroxyapatite, tricalcium phosphate, zirconia, alumina, and SiAlON ceramic. X-ray powder diffraction of each material confirmed that the chips were crystalline, with little amorphous character that could result from remaining polymeric binder, and were composed entirely out of the ceramic feedstock. Surface morphologies and roughnesses were characterized using atomic force microscopy. Human bone marrow stem cells cultured with osteogenic supplements on each material type expressed alkaline phosphatase levels, an early marker of osteogenic differentiation, on par with cells cultured on a glass control. However, cells cultured on the tricalcium phosphate-containing material expressed lower levels of ALP suggesting that osteoinduction was impaired on this material. Further analyses should be conducted with these materials to identify underlying issues of the combination of material and analysis method.

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