scholarly journals Dual Thermo- and Photo-Responsive Micelles Based on Azobenzene-Containing Random Copolymer

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 2
Author(s):  
Chuan Yan ◽  
Liqin Yang ◽  
Xiangquan Mo ◽  
Keying Chen ◽  
Weiya Niu ◽  
...  
Keyword(s):  
Fluorescence Probe ◽  
Uv Light ◽  
Nile Red ◽  
Random Copolymer ◽  
Solution Temperature ◽  
Repeated Heating ◽  
Heating And Cooling ◽  
Structure Morphology ◽  
Dialysis Method ◽  
Copolymer Poly

Amphiphilic random copolymer poly(methacrylamido-azobenzene)-ran-poly(2-hydroxyethylacrylate) (PMAAAB-ran-PHEA) was synthesized via hydrolysis of poly(methacrylamido-azobenzene)-ran-poly[2-((2′-tetrahydropyranyl)oxy)ethylacrylate] (PMAAAB-ran-P(THP-HEA)), which was prepared by conventional radical polymerization. PMAAAB-ran-PHEA micelles were then prepared via dialysis method against water with DMF as solvent. The structure, morphology, size, and low critical solution temperature (LCST) of PMAAAB-ran-PHEA and its micelles were determined by 1H-NMR, GPC, TEM, and DLS. The thermo- and photo-responsive behaviors of the resulting polymer micelles were investigated with Nile red as a fluorescence probe. The results showed that PMAAAB-ran-PHEA micelles were porous or bowl-shaped and its size was 135–150 nm, and its LCST was 55 °C when FMAAAB of the random copolymer was 0.5351; the hydrophobicity of the micellar core was changed reversibly under the irradiation of UV light and visible light without release of Nile red or disruption of micelles; the size and solubilization capacity of the micelles were dependent on temperature, and Nile red would migrate for many times between the water phase and the micelles, and finally increasingly accumulated during the repeated heating and cooling processes.

POTOMAC

Alloy Digest ◽  
1975 ◽  
Vol 24 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Heat Treating ◽  
General Purpose ◽  
Low Carbon ◽  
Repeated Heating ◽  
Temperature Changes ◽  
Heating And Cooling ◽  
Temperature Performance ◽  
Heat Checking

Abstract POTOMAC is a general-purpose, low-carbon, chromium-molybdenum-tungsten hot-work steel. It has excellent resistance to shock and heat checking after repeated heating and cooling. Potomac is suitable for hot-work applications involving severe conditions of shock and sudden temperature changes. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, and machining. Filing Code: TS-290. Producer or source: Allegheny Ludlum Corporation.

Highly efficient single-layer blue polymer light-emitting diodes based on hole-transporting group substituted poly(fluorene-co-dibenzothiophene-S,S-dioxide)

2017 ◽  
Vol 5 (37) ◽  
pp. 9680-9686 ◽  
Author(s):  
Feng Peng ◽  
Na Li ◽  
Lei Ying ◽  
Wenkai Zhong ◽  
Ting Guo ◽  
...  
Keyword(s):  
Blue Light ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Single Layer ◽  
Random Copolymer ◽  
Hole Transport ◽  
Light Emitting ◽  
Hole Transporting ◽  
Polymer Light Emitting Diodes ◽  
Copolymer Poly

We developed a series of high-performance blue light-emitting polymers that contain hole-transport moieties comprising carbazole or triphenylamine substituents in the side chains of random copolymer poly(fluorene-co-dibenzothiophene-S,S-dioxide) (PFSO).

scholarly journals Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4066
Author(s):  
David Herrera Robalino ◽  
María del Mar Durán del Amor ◽  
Carmen María Almagro Gómez ◽  
José Ginés Hernández Cifre
Keyword(s):  
Gold Nanoparticles ◽  
High Ionic Strength ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Aggregation Process ◽  
Critical Solution Temperature ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Copolymer Poly ◽  
Positively Charged

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.

scholarly journals Fluorescence Tumor-Imaging Using a Thermo-Responsive Molecule with an Emissive Aminoquinoline Derivative

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 782 ◽  
Author(s):  
Takeru Araki ◽  
Yasufumi Fuchi ◽  
Shuhei Murayama ◽  
Ryoma Shiraishi ◽  
Tokimi Oyama ◽  
...  
Keyword(s):  
Cloud Point ◽  
Intravenous Administration ◽  
Tumor Tissue ◽  
Tumor Imaging ◽  
Fluorescence Probe ◽  
Local Heat ◽  
Solution Temperature ◽  
Lcst Behavior

We synthesized (2,4-trifluoromethyl-7-N-bis(2,5,8,11-tetraoxatridecane-13-yl)-aminoquinoline) TFMAQ-diEg4, an emissive aminoquinoline derivative that incorporated two tetraethyleneglycol chains into an amino group. TFMAQ-diEg4 showed fluorescence and thermo-responsive properties accompanied by a lower critical solution temperature (LCST), due to the introduction of the oligoethylene glycol chain. This thermo-responsive LCST behavior occurred at the border of a cloud point. Below and above the cloud point, self-assemblies of 6-7-nm nanoparticles and ~2000-nm microparticles were observed, in vitro. In addition, TFMAQ-diEg4 showed a high solubility, over 20 mM for aqueous solution, in vivo, which not only prevented thrombosis but also allowed various examinations, such as single intravenous administration and intravenous drips. Intravenous administration of TFMAQ-diEg4, to tumor-bearing, mice led to the accumulation of the molecule in the tumor tissue, as observed by fluorescence imaging. A subset of mice was treated with local heat around their tumor tissue and an intravenous drip of TFMAQ-diEg4, which led to a high intensity of TFMAQ-diEg4 emission within the tumor tissue. Therefore, we revealed that TFMAQ-diEg4 was useful as a fluorescence probe with thermo-responsive properties.

scholarly journals Formation of Incrustations during the Cocombustion of Biomass in Fluidised Bed Boilers

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Petr Buryan
Keyword(s):  
Raw Materials ◽  
Combustion Process ◽  
Power Equipment ◽  
Fluidised Bed ◽  
Boiler Furnace ◽  
Repeated Heating ◽  
Equipment Operation ◽  
Heating And Cooling ◽  
First Pass ◽  
Pass Through

In this article, we focus on causes of formation of incrustations in fluidised bed boilers that result from combustion of biomass-containing energy-producing raw materials and can significantly limit the efficiency of the respective power equipment operation. We applied laboratory procedures followed for assessment of characteristic eutectics of mixtures of coal ashes, desulphurisation components (dolomite and limestone), and woodchip ashes. Our analysis proved that combustion of these (or similar) raw materials, accompanied by repeated heating and cooling of combustion and flue gas desulphurisation products, leads to the formation of unfavourable incrustations. These incrustations can grow up to several tens of centimetres in size, thereby significantly restricting the power equipment functionality. They arise due to incrust reheating that results in the formation of eutectics, which have lower melting temperatures than that during their first pass through the combustion process. The same holds for desulphuriation components themselves. Formation of these new eutectics can be attributed both to recycling of substances produced during the first pass through the furnace as well as to mixtures formed both from recycled materials and from components initially combusted in the boiler furnace.

scholarly journals Analytical Modeling of Residual Stress in Laser Powder Bed Fusion Considering Part’s Boundary Condition

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 337 ◽  
Author(s):  
Elham Mirkoohi ◽  
Hong-Chuong Tran ◽  
Yu-Lung Lo ◽  
You-Cheng Chang ◽  
Hung-Yu Lin ◽  
...  
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Kinematic Hardening ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Repeated Heating ◽  
Powder Bed ◽  
Heating And Cooling ◽  
Body Load ◽  
Point Body

Rapid and accurate prediction of residual stress in metal additive manufacturing processes is of great importance to guarantee the quality of the fabricated part to be used in a mission-critical application in the aerospace, automotive, and medical industries. Experimentations and numerical modeling of residual stress however are valuable but expensive and time-consuming. Thus, a fully coupled thermomechanical analytical model is proposed to predict residual stress of the additively manufactured parts rapidly and accurately. A moving point heat source approach is used to predict the temperature field by considering the effects of scan strategies, heat loss at part’s boundaries, and energy needed for solid-state phase transformation. Due to the high-temperature gradient in this process, the part experiences a high amount of thermal stress which may exceed the yield strength of the material. The thermal stress is obtained using Green’s function of stresses due to the point body load. The Johnson–Cook flow stress model is used to predict the yield surface of the part under repeated heating and cooling. As a result of the cyclic heating and cooling and the fact that the material is yielded, the residual stress build-up is precited using incremental plasticity and kinematic hardening behavior of the metal according to the property of volume invariance in plastic deformation in coupling with the equilibrium and compatibility conditions. Experimental measurement of residual stress was conducted using X-ray diffraction on the fabricated IN718 built via laser powder bed fusion to validate the proposed model.

scholarly journals Synthesis and Self-Assembly of Poly(N-Vinylcaprolactam)-b-Poly(ε-Caprolactone) Block Copolymers via the Combination of RAFT/MADIX and Ring-Opening Polymerizations

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1252
Author(s):  
Rodolfo M. Moraes ◽  
Layde T. Carvalho ◽  
Gizelda M. Alves ◽  
Simone F. Medeiros ◽  
Elodie Bourgeat-Lami ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Ring Opening ◽  
Chain Transfer ◽  
Fluorescence Probe ◽  
Size Exclusion ◽  
Proton Nuclear Magnetic Resonance ◽  
Solution Temperature ◽  
Copolymer Composition ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

Well-defined amphiphilic, biocompatible and partially biodegradable, thermo-responsive poly(N-vinylcaprolactam)-b-poly(ε-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerizations (ROP). Poly(N-vinylcaprolactam) containing xanthate and hydroxyl end groups (X–PNVCL–OH) was first synthesized by RAFT/macromolecular design by the interchange of xanthates (RAFT/MADIX) polymerization of NVCL mediated by a chain transfer agent containing a hydroxyl function. The xanthate-end group was then removed from PNVCL by a radical-induced process. Finally, the hydroxyl end-capped PNVCL homopolymer was used as a macroinitiator in the ROP of ε-caprolactone (ε-CL) to obtain PNVCL-b-PCL block copolymers. These (co)polymers were characterized by Size Exclusion Chromatography (SEC), Fourier-Transform Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), UV–vis and Differential Scanning Calorimetry (DSC) measurements. The critical micelle concentration (CMC) of the block copolymers in aqueous solution measured by the fluorescence probe technique decreased with increasing the length of the hydrophobic block. However, dynamic light scattering (DLS) demonstrated that the size of the micelles increased with increasing the proportion of hydrophobic segments. The morphology observed by cryo-TEM demonstrated that the micelles have a pointed-oval-shape. UV–vis and DLS analyses showed that these block copolymers have a temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by varying the block copolymer composition.

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