scholarly journals Synthesis, Characterization and Structure Properties of Biobased Hybrid Copolymers Consisting of Polydiene and Polypeptide Segments

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3818
Author(s):  
Nikolaos Politakos ◽  
Ioannis Moutsios ◽  
Gkreti-Maria Manesi ◽  
Dimitrios Moschovas ◽  
Ainur F. Abukaev ◽  
...  
Keyword(s):  
High Vacuum ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Hybrid Copolymers ◽  
Atomic Force ◽  
Β Sheets ◽  
Β Relaxation ◽  
Chain Conformations ◽  
Synthesized Materials ◽  
Structure Properties

Novel hybrid materials of the PB-b-P(o-Bn-L-Tyr) and PI-b-P(o-Bn-L-Tyr) type (where PB: 1,4/1,2-poly(butadiene), PI:3,4/1,2/1,4-poly(isoprene) and P(o-Bn-L-Tyr):poly(ortho-benzyl-L-tyrosine)) were synthesized through anionic and ring-opening polymerization under high-vacuum techniques. All final materials were molecularly characterized through infrared spectroscopy (IR) and proton and carbon nuclear magnetic resonance (1H-NMR, 13C-NMR) in order to confirm the successful synthesis and the polydiene microstructure content. The stereochemical behavior of secondary structures (α-helices and β-sheets) of the polypeptide segments combined with the different polydiene microstructures was also studied. The influence of the α-helices and β-sheets, as well as the polydiene chain conformations on the thermal properties (glass transition temperatures, thermal stability, α- and β-relaxation) of the present biobased hybrid copolymers, was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy (DS). The obtained morphologies in thin films for all the synthesized materials via atomic force microscopy (AFM) indicated the formation of polypeptide fibrils in the polydiene matrix.

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).

EFFECT OF ETCHING TIME ON OPTICAL AND MORPHOLOGICAL FEATURES OF N-TYPE POROUS SILICON PREPARED BY PHOTO-ELECTROCHEMICAL METHOD

2016 ◽  
Vol 78 (3) ◽  
Author(s):  
Asad A. Thahe ◽  
Noriah Bidin ◽  
Mohammed A. Al-Azawi ◽  
Naser M. Ahmed
Keyword(s):  
Porous Silicon ◽  
Gravimetric Method ◽  
Constant Current ◽  
Etching Time ◽  
Absorption Data ◽  
Time Duration ◽  
Constant Current Density ◽  
Force Microscopy ◽  
Atomic Force ◽  
Structure Properties

Achieving efficient visible photoluminescence from porous-silicon (PSi) is demanding for optoelectronic and solar cells applications. Improving the absorption and emission features of PSi is challenging. Photo-electro-chemical etching assisted formation of PSi layers on n-type (111) silicon (Si) wafers is reported. Samples are prepared at constant current density (~30 mA/cm2) under varying etching times of 10, 15, 20, 25, and 30 min. The influence of etching time duration on the growth morphology and spectral properties are inspected. Room temperature photoluminescence (PL) measurement is performed to determine the optical properties of as-synthesized samples. Sample morphologies are imaged via Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The thickness and porosity of the prepared samples are estimated using the gravimetric method. The emission and absorption data is further used to determine the samples band gap and electronic structure properties. Results and analyzed, interpreted with different mechanisms and compared.  

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.

Laser cleaning of exfoliated graphene

2012 ◽  
Vol 1455 ◽  
Author(s):  
Oliver Ochedowski ◽  
Benedict Kleine Bußmann ◽  
Marika Schleberger
Keyword(s):  
Local Heating ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ambient Conditions ◽  
Kelvin Probe ◽  
Structural Modifications ◽  
Force Microscopy ◽  
Exfoliated Graphene ◽  
Atomic Force ◽  
P Type

ABSTRACTWe have employed atomic force and Kelvin-Probe force microscopy to study graphene sheets exfoliated on TiO2 under the influence of local heating achieved by laser irradiation. Exfoliation and irradiation took place under ambient conditions, the measurements were performed in ultra high vacuum. We show that after irradiation times of 6 min, an increase of the surface potential is observed which indicates a decrease of p-type carrier concentration. We attribute this effect to the removal of adsorbates like water and oxygen. After irradiation times of 12 min our topography images reveal severe structural modifications of graphene. These resemble the nanocrystallite network which form on graphene/SiO2 but after much longer irradiation times. From our results we propose that short laser heating at moderate powers might offer a way to clean graphene without inducing unwanted structural modifications.

Stereocomplex electrospun fibers from high molecular weight of poly(L-lactic acid) and poly(D-lactic acid)

2020 ◽  
Vol 40 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Homa Maleki ◽  
Hossein Barani
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Thermal Properties ◽  
High Molecular Weight ◽  
Chemical Properties ◽  
Electrospun Fibers ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electrospinning Method

AbstractThe stereocomplex formation is a promising method to improve the properties of poly(lactide) (PLA)-based products due to the strong interaction of the side-by-side arrangement of the molecular chains. Recently, electrospinning method has been applied to prepare PLA stereocomplex, which is more convenient. The objective of the current study is to make stereocomplexed PLA nanofibers using electrospinning method and compare their properties and structures with pure poly(l-lactide) (PLLA) fibers. The stereocomplexed fibers were electrospun from a blend solution of high molecular weight PLLA and poly(d-lactide) (1:1 ratio). The morphology of the obtained electrospun fibers was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Differential scanning calorimetry was applied to study their thermal properties and crystallinity. Fourier transform infrared spectroscopy (FTIR) test was conducted on the samples to characterize their chemical properties. The SEM and AFM images indicated that smooth uniform fibers with a cylindrical structure were produced. Besides, the FTIR results and thermal properties confirmed that only stereocomplex crystallites formed in the resulting fibers via the electrospinning method.

GROWTH AND STUDIES OF PROPERTIES OF COPPER SUCCINATE DIHYDRATE SINGLE CRYSTALS

2013 ◽  
Vol 27 (11) ◽  
pp. 1350073
Author(s):  
M. P. BINITHA ◽  
P. P. PRADYUMNAN
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Single Crystals ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Different Temperatures ◽  
Triclinic Structure ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Single crystals of copper succinate dihydrate (CSD) with triclinic structure were grown in silica gel medium. The functional groups in the crystal were analyzed by FT-IR Spectroscopy. Atomic Force Microscopy (AFM) revealed the striations on the surface of grown crystals, which were incorporated during its time of growth. Thermal degradation studies have been carried out by Differential Scanning Calorimetry (DSC). Dielectric constant and AC conductivity have been estimated as a function of frequency at different temperatures.

scholarly journals Micro and nanocomposites of polybutadienebased polyurethane liners with mineral fillers and nanoclay: thermal and mechanical properties

2017 ◽  
Vol 15 (1) ◽  
pp. 46-52 ◽  
Author(s):  
Pablo Ross ◽  
Germán Escobar ◽  
Guillermo Sevilla ◽  
Javier Quagliano
Keyword(s):  
Thermal Properties ◽  
Polymer Chains ◽  
Toluene Diisocyanate ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Elongation At Break ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mineral Fillers

AbstractMicro and nanocomposites of hydroxyl terminated polybutadiene (HTPB)-based polyurethanes (NPU) were obtained using five mineral fillers and Cloisite 20A nanoclay, respectively. Samples were prepared by the reaction of HTPB polyol and toluene diisocyanate (TDI), and the chain was further extended with glyceryl monoricinoleate to produce the final elastomeric polyurethanes. Mechanical and thermal properties were studied, showing that mineral fillers (20%w/w) significantly increased tensile strength, in particular nanoclay (at 5% w/w). When nanoclay-polymer dispersion was modified with a silane and hydantoin-bond promoter, elongation at break was significantly increased with respect to NPU with C20A. Thermal properties measured by differential scanning calorimetry (DSC) were not significantly affected in any case. The molecular structure of prepared micro and nanocomposites was confirmed by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. Interaction of fillers with polymer chains is discussed, considering the role of silanes in compatibilization of hydrophilic mineral fillers and hydrophobic polymer. The functionalization of nanoclay with HMDS silane was confirmed using FTIR. Microstructure of NPU with C20A nanoclay was confirmed by Atomic Force Microscopy (AFM).

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.

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