scholarly journals Temperature-Sensitive Poly(N-isopropylacrylamide)/Konjac Glucomannan/Graphene Oxide Composite Membranes with Improved Mechanical Property, Swelling Capability, and Degradability

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Guohong Zou ◽  
Juan Shen ◽  
Peizhen Duan ◽  
Xu Xia ◽  
Rigui Chen ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Graphene Oxide ◽  
Enzymatic Degradation ◽  
Composite Membranes ◽  
Konjac Glucomannan ◽  
Temperature Sensitive ◽  
Scanning Calorimetry ◽  
Solution Blending ◽  
Phase Transition Temperatures ◽  
Potential Applications

Temperature-sensitive poly(N-isopropylacrylamide)/konjac glucomannan/graphene oxide (PNIPAM/KGM/GO) composite membranes were prepared by solution blending using calcium ions as a cross-linker. The composite membranes were characterized by Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), and differential scanning calorimetry (DSC). The swelling, mechanical property, phase transformation behaviors, and enzymatic degradation activities were also determined. Results revealed that the phase transition temperatures of all the composite membranes were approximately 35°C. The PNIPAM/KGM/GO composite membranes showed enhanced mechanical property. The swelling behavior and enzymatic degradation of the PNIPAM/KGM/GO composite membranes improved compared with those of conventional PNIPAM hydrogel and PNIPAM/KGM composite membranes. Thus, the PNIPAM/KGM/GO composite membranes have potential applications in the biomedical field as skin dressings.

scholarly journals Adamantane-Modified Graphene Oxide for Cyanate Ester Resin Composites with Improved Properties

2019 ◽  
Vol 9 (5) ◽  
pp. 881 ◽  
Author(s):  
Zhicong Miao ◽  
Juntao Shi ◽  
Tianjiao Liu ◽  
Peng Li ◽  
Zhiqiang Su ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Dielectric Constant ◽  
Graphene Oxide ◽  
Interfacial Polarization ◽  
Cyanate Ester ◽  
Scanning Calorimetry ◽  
Modified Graphene Oxide ◽  
Potential Applications ◽  
Cure Temperature ◽  
Modified Graphene

The conjugation of graphene and polymers has attracted great attention for the fabrication of functional hybrid nanomaterials. Here, we demonstrate the modification of graphene oxide (GO) with adamantane (AMT) through the diimide-activated amidation reaction. The modification of GO with AMT improves the dispersion and decreases the interfacial polarization of GO, causing a lower dielectric constant for the fabricated GO/AMT hybrid materials. The structures of GO/AMT were studied by Fourier transform infrared spectroscopy and Raman spectroscopy. Furthermore, the mechanical properties, thermal stability, and dielectric constant of GO/AMT composites were measured at a low cured temperature using various techniques, such as differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis. It was found that the synthesized GO/AMT materials with different contents were blended into cyanate ester (CE) resins, resulting in a lower cure temperature, smaller dielectric constant, higher thermal stability, and stronger water resistance. It is expected that this novel GO/AMT-CE material will have potential applications for replacing traditional thermosetting resins.

scholarly journals Study of microstructure, hardness and thermal properties of Sn-Bi alloys

2021 ◽  
pp. 21-21
Author(s):  
Kristina Bozinovic ◽  
Dragan Manasijevic ◽  
Ljubisa Balanovic ◽  
Milan Gorgievski ◽  
Uros Stamenkovic ◽  
...  
Keyword(s):  
Thermal Properties ◽  
High Reliability ◽  
Low Cost ◽  
Flash Method ◽  
Thermal Interface Materials ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Phase Transition Temperatures ◽  
Potential Applications ◽  
Lead Free Solders

Lead-free solders have become a main focus of the electronic industry in recent years, because of the high toxicity of lead. Alloys based on the Sn-Bi system figure as potential replacements for Sn-Pb alloys in soldering due to favorable properties and low cost. One of the main advantages of these alloys are low melting temperatures, while additional advantages include good compatibility with substrates, low process temperature, high reliability, and potential applications in conjunction with reduced graphene oxide nanosheets as thermal interface materials. In this paper, characterization of microstructural and thermal properties as well as hardness measurements of seven alloys of different Sn-Bi compositions are performed. Structural properties of the samples were analyzed using optical microscopy and scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS). Thermal conductivity of the samples was investigated using the xenon-flash method, and phase transition temperatures were measured using the differential scanning calorimetry (DSC) analysis.

scholarly journals Production and enzymatic degradation of poly(ε-caprolactone)/graphene oxide composites

2020 ◽  
Vol 10 (6) ◽  
pp. 866-876
Author(s):  
V. Martínez-Ramón ◽  
I. Castilla-Cortázar ◽  
A. Vidaurre ◽  
A. J. Campillo-Fernández
Keyword(s):  
Graphene Oxide ◽  
Enzymatic Degradation ◽  
Morphological Changes ◽  
Phosphate Buffer Solution ◽  
Oxide Content ◽  
Buffer Solution ◽  
Scanning Calorimetry ◽  
Weight Loss Data ◽  
Mixing Method ◽  
Oxide Composites

Poly(ε-caprolactone) (PCL) based composites containing different graphene oxide (GO) contents (0.1, 0.2 and 0.5 wt%) were produced by the solution mixing method followed by compression molding and enzymatically degraded in a pH 7.4 phosphate buffer solution containing Pseudomonas lipase at 37 °C. Morphological changes, molecular weight, calorimetric and mechanical properties were analyzed according to graphene oxide content. The study of tensile properties showed that the composites increased their Young’s modulus, while tensile strength and elongation at break decreased to significantly less than that of neat PCL. PCL composite crystallinity was evaluated by differential scanning calorimetry (DSC). It was found that incorporating GO can reduce nucleation activity as well as crystallization rates, from 67.6% for neat PCL to 50.6% for a composite with 0.5 wt% GO content. For enzymatic degradation, the weight loss data showed that incorporating GO into the PCL significantly altered enzymatic degradation. The presence of GO did not alter PCL’s hydrolysis mechanism, but did slow down composite enzymatic degradation in proportion to the percentage of filler content.

scholarly journals Extraordinary thermal behavior of graphene oxide in air for electrode applications

2021 ◽  
Author(s):  
Joong Tark Han ◽  
Joon Young Cho ◽  
Jeong Hoon Kim
Keyword(s):  
Thermal Stability ◽  
Graphene Oxide ◽  
Physical Properties ◽  
Thermal Behavior ◽  
Stability Of Solution ◽  
Exfoliated Graphene ◽  
Potential Applications ◽  
Thermal Stability Of

The thermal stability of solution-exfoliated graphene oxide (GO) in air is one of the most important physical properties influencing its potential applications. To date, majority of the GO prepared by...

scholarly journals On the Effectiveness of Oxygen Plasma and Alkali Surface Treatments to Modify the Properties of Polylactic Acid Scaffolds

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1643
Author(s):  
Ricardo Donate ◽  
María Elena Alemán-Domínguez ◽  
Mario Monzón
Keyword(s):  
Surface Properties ◽  
Enzymatic Degradation ◽  
Oxygen Plasma ◽  
Physicochemical Characterization ◽  
Surface Treatments ◽  
Carboxyl Groups ◽  
Scanning Calorimetry ◽  
Water Contact ◽  
Angle Measurements ◽  
3D Printed

Surface modification of 3D-printed PLA structures is a major issue in terms of increasing the biofunctionality and expanding the tissue engineering applications of these parts. In this paper, different exposure times were used for low-pressure oxygen plasma applied to PLA 3D-printed scaffolds. Alkali surface treatments were also evaluated, aiming to compare the modifications introduced on the surface properties by each strategy. Surface-treated samples were characterized through the quantification of carboxyl groups, energy-dispersive X-ray spectroscopy, water contact angle measurements, and differential scanning calorimetry analysis. The change in the surface properties was studied over a two-week period. In addition, an enzymatic degradation analysis was carried out to evaluate the effect of the surface treatments on the degradation profile of the 3D structures. The physicochemical characterization results suggest different mechanism pathways for each type of treatment. Alkali-treated scaffolds showed a higher concentration of carboxyl groups on their surface, which enhanced the enzymatic degradation rate, but were also proven to be more aggressive towards 3D-printed structures. In contrast, the application of the plasma treatments led to an increased hydrophilicity of the PLA surface without affecting the bulk properties. However, the changes on the properties were less steady over time.

scholarly journals Lerf–Klinowski-type models of graphene oxide and reduced graphene oxide are robust in analyzing non-covalent functionalization with porphyrins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexandra Siklitskaya ◽  
Ewelina Gacka ◽  
Daria Larowska ◽  
Marta Mazurkiewicz-Pawlicka ◽  
Artur Malolepszy ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Excited States ◽  
Reduced Graphene ◽  
Simulation Protocol ◽  
Potential Applications ◽  
H 26 ◽  
High Level ◽  
Experimental And Theoretical Studies ◽  
Low Solubility

AbstractGraphene-based nanohybrids are good candidates for various applications. However, graphene exhibits some unwanted features such as low solubility in an aqueous solution or tendency to aggregate, limiting its potential applications. On the contrary, its derivatives, such as graphene oxide (GO) and reduced graphene oxide (RGO), have excellent properties and can be easily produced in large quantities. GO/RGO nanohybrids with porphyrins were shown to possess great potential in the field of photocatalytic hydrogen production, pollutant photodegradation, optical sensing, or drug delivery. Despite the rapid progress in experimental research on the porphyrin-graphene hybrids some fundamental questions about the structures and the interaction between components in these systems still remain open. In this work, we combine detailed experimental and theoretical studies to investigate the nature of the interaction between the GO/RGO and two metal-free porphyrins 5,10,15,20-tetrakis(4-aminophenyl) porphyrin (TAPP) and 5,10,15,20-tetrakis(4-hydroxyphenyl) porphyrin (TPPH)]. The two porphyrins form stable nanohybrids with GO/RGO support, although both porphyrins exhibited a slightly higher affinity to RGO. We validated finite, Lerf–Klinowski-type (Lerf et al. in J Phys Chem B 102:4477, 1998) structural models of GO ($$\hbox {C}_{59}\hbox {O}_{26}\hbox {H}_{26}$$ C 59 O 26 H 26 ) and RGO ($$\hbox {C}_{59}\hbox {O}_{17}\hbox {H}_{26}$$ C 59 O 17 H 26 ) and successfully used them in ab initio absorption spectra simulations to track back the origin of experimentally observed spectral features. We also investigated the nature of low-lying excited states with high-level wavefunction-based methods and shown that states’ density becomes denser upon nanohybrid formation. The studied nanohybrids are non-emissive, and our study suggests that this is due to excited states that gain significant charge-transfer character. The presented efficient simulation protocol may ease the properties screening of new GO/RGO-nanohybrids.

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