EVA incorporating organo-MMT exhibits greater toughness and biostability at high strain, at which point the organo-MMT is exfoliated and introduces a more tortuous path for the entrance of permeants.
In this study, a novel desulfurization method was conducted using the superoxide ion (O 2
•−) generated chemically in four ionic liquids (ILs): 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, N-methoxyethyl-N-methylmorpholinium bis(trifluoromethylsulfonyl)imide, 1-(2-methoxyethyl)-1-methylpiperidinium tris(pentafluoroethyl)trifluorophosphate, and 4-(2-methoxyethyl)-4-methylmorpholinium tris(pentafluoroethyl)trifluorophosphate. Remarkably, it was found that O 2•− can convert the sulfur compounds (i.e., thiophene and 2-methylthiophene) dissolved in these ILs. The products of the conversion were identified as H 2 O, CO 2 , and SO 3 . The conversion percentage ranged from 35 to 99% for thiophene and 20 to 96% for 2-methylthiophene. In addition, a mechanism was proposed for this conversion. Furthermore, the effect of temperature on this reaction was studied and the solubility of sulfur compounds in these ILs was determined. The ILs did not only behave as media for the generation of O 2
•−, but they also possessed catalytic activity to accelerate the reaction rate between O 2•− and substrates.
The
generation of superoxide (O2
•–) in ionic liquids (ILs) has been used to destroy hazardous materials.
In this study, O2
•– was used for
the oxidative desulfurization of benzothiophene (BT) and dibenzothiophene
(DBT) in two ILs as reaction media. The O2
•– was released by dissolving potassium superoxide in 1-butyl-1-methylpyrrolidinium
bis(trifluoromethylsulfonyl)imide [BMPyrr][TFSI] and n-methoxyethyl-n-methylmorpholinium bis(trifluoromethylsulfonyl)imide
[MOEMMor][TFSI]. The highest conversion percentages for BT in [MOEMMor][TFSI]
and [BMPyrr][TFSI] were 99.4 and 96.6%, respectively, and the highest
conversion percentages for DBT in [MOEMMor][TFSI] and [BMPyrr][TFSI]
were 98.3 and 94.3%, respectively. As the temperature was increased,
the reaction of the O2
•– with
BT and DBT was enhanced significantly. The BT was converted easier
than DBT due to the nucleophilic characteristic of the O2
•– and the higher electron density of the
sulfur atom in DBT than that in BT. In addition, the ILs had a clear
effect on the oxidative desulfurization reaction, in which the O2
•– demonstrated a higher conversion
percentage in [MOEMMor][TFSI] than in [BMPyrr][TFSI]. This was the
result of the stability of the O2
•– in the ILs that were used in the study. In addition, the σ-potential
obtained using the “Conductor-like Screening Model for Real
Solvent” (COSMO-RS) indicated that [MOEMMor]+ was
a superior hydrogen bond donor and had a stronger affinity for the
hydrogen bond acceptor than [BMPyrr]+. The reaction mechanism
was reported, and no toxic byproducts were detected. This is the first
study in which O2
•– in ILs was
used for the conversion of BT and DBT to nonhazardous compounds, and
this technique can be used for other hazardous materials.
Halloysite nanotubes (HNTs) reinforced polylactic acid (PLA) nanocomposite films were utilized for different applications, such as packaging, drug recover and other applications. The incorporation of plasticizer into polymer nanocomposites modifies some of their functional and physical properties, such as increasing flexibility, moisture sensitivity, in addition to other functional properties. However, the effects of Polyethylen glycol (PEG) and sesame oil (SO) on selected physical properties (moisture content (MC), contact angle (CA) and water vapor permeability (WVP)) of PLA)/HNTs bionanocomposite films were examined. The plasticized PLA/HNTs (5 wt % HNTs loading) bionanocomposite films were prepared using the solution casting method at room temperature. The concentrations of each plasticizer that used indivisually were (0, 10, 20 and 30 wt %). Results show that the increasing of PEG content led to increase in moisture content and water vapor permeability and decrease in contact angle of the films. On the contrary, the increasing of SO levels led to decrease in moisture content and water vapor permeability and increase in contact angle of the films. Differences in measured physical properties of films with plasticizer type and concentration may be attributed to differences in the hydrophilic and hydrophobic properties of the plasticizers. SO was the plasticizer that showed the most interested effect (low moisture content and water vapor permeability) on PLA/HNTs films for food packaging applications compared to PEG.
The viability of metallocene linear low density polyethylene (mLLDPE) nanocomposites is being investigated as a new material for biomedical application. The effect of filler loadings on the ambient andin vitro(after being exposed in oxidizing condition, 37°C) mechanical properties was studied. We observed that, the mLLDPE nanocomposites have higher mechanical property values as compared to the neat mLLDPE. Furthermore, these properties were less affected by thein vitroconditions. The best ambient andin vitromechanical properties were achived when 3wt% of organically modified MMT (organo-MMT) was added into the mLLDPE. It was postulated that the presence of MMT layered structure introduced a more tortous path for the diffusing of oxidant molecules, thereby decreasing their permeability towards mLLDPE molecular chains. The smaller amount of oxidants entering the molecular chains resulted in greater retention of mechanical properties when testedin vitro. This preliminary biostability studies show promising properties of the mLLDPE nanocomposite which possess the potential to be further developed for biomedical devices.
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