scholarly journals High-Yield Synthesis of Uniform Ag Nanowires with High Aspect Ratios by Introducing the Long-Chain PVP in an Improved Polyol Process

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Jie-Jun Zhu ◽  
Cai-Xia Kan ◽  
Jian-Guo Wan ◽  
Min Han ◽  
Guang-Hou Wang
Keyword(s):  
Silver Nanowires ◽  
Polyol Process ◽  
High Yield ◽  
Chemical Adsorption ◽  
Capping Agent ◽  
Molecular Weights ◽  
Aspect Ratios ◽  
Initial Stage ◽  
Ag Nanowires ◽  
Long Chain

Polyvinyl pyrrolidone (PVP) with different molecular weights was used as capping agent to synthesize silver nanowires through a polyol process. The results indicated that the yields and aspect ratios of silver nanowires were controlled by the chain length of PVP and increased with increasing the molecular weight (MW) of PVP. When the long-chain PVP-K90 (MW = 800,000) was used, the product was uniform in size and was dominated by nanowires with high aspect ratios. The growth mechanism of the nanowires was studied. It is proposed that the chemical adsorption of Ag+on the PVP chains at the initial stage promotes the growth of Ag nanowires.

scholarly journals Polyol Silver Nanowire Synthesis and the Outlook for a Green Process

2020 ◽  
Vol 2020 ◽  
pp. 1-25 ◽  
Author(s):  
Shohreh Hemmati ◽  
Michael T. Harris ◽  
Dale P. Barkey
Keyword(s):  
Silver Nanowires ◽  
Synthesis Method ◽  
Polyol Process ◽  
Silver Nanowire ◽  
Polyol Synthesis ◽  
High Yield ◽  
Silver Nanostructures ◽  
Wearable Electronics ◽  
Aspect Ratios ◽  
Size And Morphology

Silver nanowires (AgNWs) have a broad range of applications including nanoelectronics, energy conversion, health care, solar cells, touch screens, sensors and biosensors, wearable electronics, and drug delivery systems. As their characteristics depend strongly on their size and morphology, it is essential to find the optimal and most cost-effective synthesis method with precise control over the size and morphology of the wires. Various methods for AgNW synthesis have been reported along with process optimization and novel techniques to increase the yield and aspect ratios of synthesized AgNWs. The most promising processes for synthesis of AgNWs are wet chemical techniques, in which the polyol process is low cost and simple and provides high yield compared to other chemical methods. Reaction mechanism is one of the most important factors in strategies to control the process. Our purpose here is to provide an overview on the main findings regarding synthesis, preparation, and characterization of AgNWs. Recent efforts in the polyol synthesis of AgNWs are summarized with respect to product morphology and size, reaction conditions, and characterization techniques. The effect of essential factors such as reagent concentration and preparation, temperature, and reaction atmosphere that control the size, morphology, and yield of synthesized AgNWs is reviewed. Moreover, a review on the novel modified polyol process and reactor design such as continuous millifluidic and flow reactors to increase the yield of synthesized AgNWs on large scales is provided. The most recent proposed growth mechanisms and kinetics behind the polyol process are addressed. Finally, comparatively few available studies in green and sustainable development of 1D silver nanostructures through the application of natural products with inherent growth termination, stabilization, and capping characteristics are reviewed to provide an avenue to natural synthesis pathways to AgNWs. Future directions in both chemical and green synthesis approaches of AgNWs are addressed.

scholarly journals Highly Ordered Arrays of Silver Nanowires for Transparent Conducting PET Film 

2020 ◽  
Author(s):  
Gul Naz ◽  
Hafsa Asghar ◽  
Junaid Jalil ◽  
Muhammad Arshad ◽  
Rashid Ahmed ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Silver Nanowires ◽  
Average Diameter ◽  
Hydroxyethyl Cellulose ◽  
High Yield ◽  
X Rays ◽  
Aspect Ratios ◽  
Vis Spectroscopy ◽  
Mechanical Pressing ◽  
Pet Film

Silver nanowires (AgNWs) with ultra-high purity and high yield are successfully synthesized by employing a modified facile polyol method using PVP as capping and stabilizing agent. The reaction is carried out at a moderate temperature of 140 °C and mild stirring rate for about 3 hours. The prepared AgNWs are characterized by UV-Vis spectroscopy, scanning electron microscopy (SEM), X-rays diffraction (XRD) and PL spectroscopy. The luminescent AgNWs exhibit red emission which is accredited to the deep holes. The SEM results confirm the formation of AgNWs of length ranging from 35 to 40 µm and an average diameter of about 86 nm, thus their aspect ratios exceed 400. The AgNWs and hydroxyethyl cellulose (HEC) based ink is transferred to polyethylene terephthalate (PET) film by simple mechanical pressing. The PET film has retained its transparency and flexibility after AgNWs ink coating. The % transmittance of as-prepared PET film is estimated to be about 92.5% with a lower sheet resistance value ~ 20 Ω, which can make it a potential substitute to commonly used expensive indium tin oxide (ITO) films in the field of optoelectronics.  

scholarly journals Application of Waste Engine Oil for Improving Ilmenite Flotation Combined with Sodium Oleate Collector

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1242
Author(s):  
Qingyao Yu ◽  
Fuqiang Tian ◽  
Yijun Cao ◽  
Guixia Fan ◽  
Haiqing Hao ◽  
...  
Keyword(s):  
Sodium Oleate ◽  
Strong Interaction ◽  
Adsorption Mechanism ◽  
Engine Oil ◽  
Molar Ratio ◽  
Chemical Adsorption ◽  
Synergetic Effects ◽  
Waste Engine Oil ◽  
Environmentally Friendly Approach ◽  
Long Chain

Collectors commonly have synergetic effects in ores flotation. In this work, a waste engine oil (WEO) was introduced as a collector to an ilmenite flotation system with sodium oleate (NaOL). The results show that the floatability of ilmenite was significantly improved by using WEO and NaOL as a combined collector. The recovery of ilmenite was enhanced from 71.26% (only NaOL) to 93.89% (WEO/NaOL combined collector) at the pH of 6.72. The optimum molar ratio of NaOL to WEO was about 2.08 to 1. The WEO and NaOL also have synergetic effects for the collection of ilmenite, because to obtain the ilmenite recovery of 53.96%, the dosage of 45 mg/L NaOL is equal to 38.56 mg/L WEO/NaOL combined collector (30 mg/L NaOL + 8.56 mg/L WEO). In other words, 15 mg/L of NaOL can be replaced by 8.56 mg/L of WEO. It is an effective way to reduce the dosage of the collector and reuse WEO. Therefore, it is a highly valuable and environmentally friendly approach for WEO reuse. WEO mainly consists of oxygen functional groups, aromatics, and long-chain hydrocarbons, especially for the RCONH2 and RCOOH, thereby forming a strong interaction on the ilmenite surface. The adsorption mechanism of waste engine oil and sodium oleate on the ilmenite surface is mainly contributed by chemical adsorption. Therefore, WEO exhibits superior synergistic power with NaOL as a combined collector. Herein, this work provided an effective collector for ilmenite flotation and a feasible approach for reducing NaOL dosage and recycling WEO.

scholarly journals Long-chain aliphatic wax esters isolated from the sponge Chalinula saudensis (Demospongia) along the Jeddah coast of the Red Sea

2011 ◽  
Vol 59 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Abdulmohsin Al-Sofyani ◽  
Radwan K Al-Farawati ◽  
Amr A ElMaradny ◽  
Gul R Niaz
Keyword(s):  
Vital Role ◽  
Marine Organisms ◽  
Fatty Acid Esters ◽  
Long Chain Fatty Acid ◽  
Molecular Weights ◽  
Chloroform Layer ◽  
Layer Chromatography ◽  
Preparative Layer Chromatography ◽  
Acid Esters ◽  
Long Chain

The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isolated and identified. In this study, the total crude organic matter of the sponge was extracted by solvents. The total crude extract was further separated by partitioning it with hexane and water, then with water and chloroform, and finally with water and t-butanol. The chloroform layer was subjected to separation by preparative layer chromatography on silica. One fraction contained four long-chain fatty acid esters, C28H56O2, C30H60O2, C32H62O2 and C36H70 O2. The second ester, C30H60O2, has been identified in the fire corals Millepora dichotoma and Millepora platyphylla. The others have not previously been reported from marine organisms; however similar long-chain esters with different long aliphatic chains and with different molecular weights have been identified from other marine organisms. These compounds are normally waxy and their presence in Chalinula saudensis plays a vital role in the biosynthetic pathways. They also act as insulators against seasonal variations.

Rheology of Thermoplastic Polyurethanes

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Rheological Behavior ◽  
Thermoplastic Polyurethane ◽  
Complete Characterization ◽  
Chain Extender ◽  
Reaction Sequence ◽  
Molecular Weights ◽  
Soft Segments ◽  
Hard Segments ◽  
A Chain ◽  
Long Chain

Thermoplastic polyurethane (TPU) has received considerable attention from both the scientific and industrial communities (Hepburn 1982; Oertel 1985; Saunders and Frish 1962). Applications for TPUs include automotive exterior body panels, medical implants such as the artificial heart, membranes, ski boots, and flexible tubing. Figure 10.1 gives a schematic that shows the architecture of TPU, consisting of hard and soft segments. Hard segments, which form a crystalline phase at service temperature, are composed of diisocyanate and short-chain diols as a chain extender, while soft segments, which control low-temperature properties, are composed of difunctional long-chain polydiols with molecular weights ranging from 500 to 5000. The soft segments form a flexible matrix between the hard domains. TPUs are synthesized by reacting difunctional long-chain diol with diisocyanate to form a prepolymer, which is then extended by a chain extender via one of two routes: (1) by a dihydric glycol chain extender or (2) by a diamine chain extender. The most commonly used diisocyanate is 4,4’-diphenylmethane diisocyanate (MDI), which reacts with a difunctional polyol forming soft segments, such as poly(tetramethylene adipate) (PTMA) or poly(oxytetramethylene) (POTM), to produce TPU, in which 1,4-butanediol (BDO) is used as a chain extender. There are two methods widely used to produce TPU: (1) one-shot reaction sequence and (2) two-stage reaction sequence. The reaction sequences for both methods are well documented in the literature (Hepburn 1982). It should be mentioned that MDI/BDO/PTMA produces ester-based TPU. One can also produce ether-based TPU when MDI reacts with POTM using BDO as a chain extender. TPUs are often referred to as “multiblock copolymers.” In order to have a better understanding of the rheological behavior of TPUs, one must first understand the relationships between the chemical structure and the morphology; thus, a complete characterization of the materials must be conducted. The rheological behavior of TPU depends, among many factors, on (1) the composition of the soft and hard segments, (2) the lengths of the soft and hard segments and the sequence length distribution, (3) anomalous linkages (branching, cross-linking), and (4) molecular weight.

scholarly journals Proposed Mechanism for the High-Yield Polymerization of Oxyethyl Propiolates with Rh Complex Catalyst Using the Density Functional Theory Method

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 93 ◽  
Author(s):  
Yoshiaki Yoshida ◽  
Yasuteru Mawatari ◽  
Masayoshi Tabata
Keyword(s):  
Density Functional ◽  
Density Functional Theory Method ◽  
High Reactivity ◽  
High Yield ◽  
Complex Catalyst ◽  
Dft Methods ◽  
Functional Theory ◽  
Molecular Weights ◽  
Monomer Structure ◽  
The Density Functional Theory

In this study, poly(oxyethyl propiolate)s (POP)s featuring various oxyethylene derivatives are synthesized using a [Rh(norbornadiene)Cl]2 catalyst. In particular, POPs featuring the normal oxyethylene chain in the side-chain exhibit excellent yields and high molecular weights in methanol and N,N-dimethylformamide at 40 °C, compared with poly(n-alkyl propiolate)s (PnAP)s. The high reactivity of the oxyethyl propiolate (OP) monomers is clarified by considering the time dependences of the polymerization yields of OPs and alkyl propiolates (Aps). Furthermore, the monomer structure and intermediate conformation of the Rh complex are optimized using Density Function theory (DFT) methods (B3LYP/6-31G** and B3LYP/LANL2DZ) and a polymerization mechanism is proposed.

scholarly journals High-Yield Synthesis of Long Silver Nanowires via Chromic Chloride and a Stable Reaction Environment

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Bosheng Zhang ◽  
Rui Dang ◽  
Qigao Cao ◽  
Panchao Zhao ◽  
Kunkun Chen ◽  
...  
Keyword(s):  
Electrode Potential ◽  
Atomic Oxygen ◽  
High Efficiency ◽  
Silver Nanowires ◽  
High Yield ◽  
Synthesis Methods ◽  
Standard Electrode Potential ◽  
Oxidative Etching ◽  
Lower Standard ◽  
Chromic Chloride

The search for suitable synthesis methods and parameters capable of controlling the length, diameter, and yield of silver nanowires (AgNWs) is still an emerging strategy today. Therefore, a method for high-yield synthesis of long AgNWs via chromic chloride and a stable reaction environment was proposed. The results show that Cr3+ could restore the adsorbed atomic oxygen quickly and provide a high efficiency in the prevention of the oxidative etching, for the ion of Cr2+ oxidized to Cr3+ has a lower standard electrode potential, and a more stable reaction environment provided by the coupling method could avoid disturbing the growth of the {111} reactive sites of the wires; then, the yield and length of the AgNWs were improved. The length of the AgNWs was over 75 μm and even 160 μm; the yield of the AgNWs was over 90%, which provides the referable basis for the synthesis of ultralong AgNWs.

scholarly journals Impregnation of poly(L-lactide-ran-δ-valerolactone) with essential bark oil using supercritical carbon dioxide

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chikara Tsutsumi ◽  
Souta Manabe ◽  
Susumu Nakayama ◽  
Yuushou Nakayama ◽  
Takeshi Shiono
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Azeotropic Distillation ◽  
Proteinase K ◽  
High Yield ◽  
Feed Ratio ◽  
One Pot ◽  
Molecular Weights ◽  
Hydrolysis Process ◽  
Supercritical Carbon

Abstract This work studied the incorporation of essential bark oil from Thujopsis dolabrata var. hondae, which is known to repel various insects, in poly(L-lactide-ran-δ-valerolactone) [poly(L-LA-ran-VL)] using supercritical carbon dioxide (scCO2). The poly(L-LA-ran-VL) was synthesized by first purifying the monomers by azeotropic distillation with benzene, followed by polymerization with Sn(oct)2 using the same equipment, representing an efficient one-pot process. The copolymerization of L-LA with VL using this technique at a feed ratio of 90/10 mol/mol gave poly(L-LA-ran-VL) (91/9) with a molecular weight of 6.48 × 104 g/mol and a high yield of 74.9%. Products with molecular weights over 5.0 × 104 g/mol were obtained at L-LA feed proportions of 70 to 90%. Impregnation trials were conducted between 40 and 120 °C at 14 MPa for 3 h. The oil content of a 73/27 specimen was found to increase significantly during processing at 100 or 120 °C. During enzymatic degradation with proteinase K, the 91/9 specimen showed the fastest degradation rate. Although the 71/29 sample was slowly hydrolyzed in a phosphate buffer at pH 7.0, the release of oil vapor from this material was slightly higher than that from the 91/9 specimen, and the vapor release rate continuously increased throughout the hydrolysis process.

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