From Hollow to Solid Carbon Spheres: Time-Dependent Facile Synthesis

Kukułka, Wojciech; Wenelska, Karolina; Bača, Martin; Chen, Xuecheng

doi:10.3390/nano8100861

Cited by 24 publications

(12 citation statements)

References 46 publications

(48 reference statements)

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“…DTG makes it possible to obtain parameters related to a thermal event, such as its onset and end temperatures (To and Te), as well as the temperature at which the rate of mass change is highest (Tp). DTG has been used for thermal decomposition studies of various materials such as carbon spheres, polyaniline-cellulose nanofiber, laterite, and amyrenone [16][17][18][19]. DTG was also used to analyze the composition ratio of a polymer composite.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Residual Solvent and Drug in PLGA Microspheres by Derivative Thermogravimetry

Shim

Sah

2020

Pharmaceutics

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Thermogravimetry does not give specific information on residual organic solvents in polymeric matrices unless it is hyphenated with the so-called evolved gas analysis. The purpose of this study was to apply, for the first time, derivative thermogravimetry (DTG) to characterize a residual solvent and a drug in poly-d,l-lactide-co-glycolide (PLGA) microspheres. Ethyl formate, an ICH class 3 solvent, was used to encapsulate progesterone into microspheres. DTG provided a distinct peak, displaying the onset and end temperatures at which ethyl formate started to evolve from to where it completely escaped out of the microspheres. DTG also gave the area and height of the solvent peak, as well as the temperature of the highest mass change rate of the microspheres. These derivative parameters allowed for the measurement of the amount of residual ethyl formate in the microspheres. Interestingly, progesterone affected not only the residual solvent amount but also these derivative parameters. Another intriguing finding was that there was a linear relationship between progesterone content and the peak height of ethyl formate. The residual solvent data calculated by DTG were quite comparable to those measured by gas chromatography. In summary, DTG could be an efficient and practical quality control tool to evaluate residual solvents and drugs in various polymeric matrices.

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Section: Introductionmentioning

confidence: 99%

Assessment of Residual Solvent and Drug in PLGA Microspheres by Derivative Thermogravimetry

Shim

Sah

2020

Pharmaceutics

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“…These materials can be used in many fields, including catalysis [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], bio-nanotechnology [ 8 , 9 , 10 , 11 ], materials chemistry [ 12 , 13 ], optical devices [ 14 , 15 , 16 , 17 , 18 ], electronics [ 19 , 20 , 21 , 22 ], and magnetic devices [ 23 , 24 , 25 , 26 , 27 ]. Among the number of core-shell composite materials [ 28 , 29 , 30 , 31 , 32 ], coating desirable compounds onto a core to form luminescence materials has emerged as one of the research hot spots in recent years. When compared with unary substance, these core-shell composite materials often exhibit improved physical and chemical properties [ 33 , 34 , 35 , 36 ], such as good stability, multi-functionality, luminous intensity, fluorescence quantum efficiency, and fluorescence lifetime.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Luminescence Properties of Core-Shell-Shell Composites: SiO2@PMDA-Si-Tb@SiO2 and SiO2@PMDA-Si-Tb-phen@SiO2

Feng

Bao

et al. 2019

Nanomaterials

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Two novel core-shell composites SiO2@PMDA-Si-Tb, SiO2@PMDA-Si-Tb-phen with SiO2 as the core and terbium organic complex as the shell, were successfully synthesized. The terbium ion was coordinated with organic ligand forming terbium organic complex in the shell layer. The bi-functional organosilane ((HOOC)2C6H2(CONH(CH2)3Si(OCH2CH3)3)2 (abbreviated as PMDA-Si) was used as the first ligand and phen as the second ligand. Furthermore, the silica-modified SiO2@PMDA-Si-Tb@SiO2 and SiO2@PMDA-Si-Tb-phen@SiO2 core-shell-shell composites were also synthesized by sol-gel chemical route. An amorphous silica shell was coated around the SiO2@PMDA-Si-Tb and SiO2@PMDA-Si-Tb-phen core-shell composites. The core-shell and core-shell-shell composites both exhibited excellent luminescence in solid state. The luminescence of core-shell-shell composites was stronger than that of core-shell composites. Meanwhile, an improved luminescence stability property for the core-shell-shell composites was found in the aqueous solution. The core-shell-shell composites exhibited bright luminescence, high stability, long lifetime, and good solubility, which may present potential applications in the bio-medical field.

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“…XRD patterns showed two strong peaks: the first at around 24° and second at around 44°, which can be assigned to the stacking carbon layer structure (002) and ordered graphitic carbon structure (100) [ 36 ]. Broadening of the two peaks suggests a low degree of graphitization and the possible presence of amorphous carbon [ 37 , 38 ]. For the sample denoted as ARF_20 h/200 (treated under higher temperature (200 °C) for a longer time (20 h), a decrease of 002 peak intensity and increase of 100 peak intensity was observed in comparison with the samples prepared under mild conditions (ARF_1 h/120) or with the sample produced under pressureless conditions (RF).…”

Section: Resultsmentioning

confidence: 99%

Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

et al. 2020

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In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the effect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly different from those obtained at higher pressures. In addition, CO2 uptake was not affected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more effect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 °C, but had no effect on it at 0 °C.

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From Hollow to Solid Carbon Spheres: Time-Dependent Facile Synthesis

Cited by 24 publications

References 46 publications

Assessment of Residual Solvent and Drug in PLGA Microspheres by Derivative Thermogravimetry

Assessment of Residual Solvent and Drug in PLGA Microspheres by Derivative Thermogravimetry

Synthesis and Luminescence Properties of Core-Shell-Shell Composites: SiO2@PMDA-Si-Tb@SiO2 and SiO2@PMDA-Si-Tb-phen@SiO2

Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

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