Browsing by Subject "Antistatic"

Now showing 1 - 4 of 4

Open Access
Bioaromatic-associated multifunctionality in lignin-containing reversible elastomers
(American Chemical Society, 2023-07-12) Thys, Marlies; Kaya, Görkem Eylül; Soetemans, Lise; Van Assche, Guy; Bourbigot, Serge; Baytekin, Bilge; Vendamme, Richard; Van den Brande, Niko
The unique molecular structure of lignin, intrinsically rich in bioaromatic groups (phenolic hydroxyls), gives it, e.g., antioxidant, antistatic, antimicrobial, UV-blocking, hydrophobic, or even flame-retardant properties, which are highly interesting. An attractive strategy to use lignin as a macro-monomer for the design of functional materials that retain certain of these lignin-specific properties is to partially preserve some phenolic groups during the synthesis. In this work, we explore the properties of reversible elastomers containing a lignin fraction whose phenolic groups have only been partially modified. To do so, Kraft lignin was first fractionated and partially (89%) modified with furan groups, allowing its homogeneous incorporation in Diels-Alder formulations. The effect of the residual phenolic groups embedded in the polymer matrix was then systematically studied, focusing on the specific material properties associated with lignin. The obtained lignin-containing networks notably showed increased radical scavenging activity (which directly resulted in improved antistatic and antioxidant properties), displayed improved UV absorbance due to the presence of multiple lignin chromophores, and were even able to inhibit the growth of bacteria. This article demonstrates that tailored and partially modified lignin fractions could be used as multi-functional building blocks for the design of complex (and reversible) polymer architectures, mimicking some of the unique lignin functionalities found in nature, and this without the need to add specific additives.
Open Access
Core-shell quantum dot-embedded polymers for antistatic applications
(American Chemical Society, 2023-12-07) Ekim, Sunay Dilara; Aydın, Firdevs; Kaya, Görkem Eylül; Baytekin, H. Tarık; Asil, Demet; Baytekin, Bilge
Electrical charges develop on the surfaces of two insulator materials when they are in contact and separated. The retention of charges on insulator polymers causes material losses and hazards in industries using these polymers. Here, we show that a set of core-shell quantum dots embedded into a common polymer can destabilize the charges on the polymer. The locations of the charge carriers in the nanostructure, or the “type” of the dots, affect their discharging ability, which can also be manipulated or reverted remotely by light. The mechanism of antistatic action is presumed to contain interaction with polymer mechanospecies. The quantum dot embedding renders the polymers antistatic without changing their conductivity. Such antistatic additives, by which the polymers remain insulating, can be used to prevent static charges, e.g., in electronic coatings and in other antistatic applications.
Open Access
Lignin as an antistatic additive for common polymers
(2018-01) Bedük, Tutku
Static electricity is a common phenomenon that can causes million-dollar loses in industries such as polymer, air and space, and drug manufacture due to the detrimental effects of electrostatic discharge of the accumulated charges on surfaces. Doping of the materials, i.e. polymers, with antistatic agents can reduce or prevent these problems. So far, the antistatic additives used were chosen to make the final material/composite conductive to dissipate the surface charges, by either directly doping with conductive materials (e.g. metals or carbon powder), or by doping with additives (e.g. ions) to increase surface humidity. The doped materials usually lose their inherent properties such as the mechanical properties because of the high concentrations of the additive. To provide a more universal solution to this problem and avoid the changes in the material properties after doping, the mechanism of static charge formation, which has been on debate for many years, should be clarified. Recent studies of our group and others have shown that the main mechanism behind the charge formation on electrified (polymer) materials is the bond-breakages on the surfaces of the materials, which lead to mechanoanion, mechanocation, mechanoradical active ends. The former two accounts for the charge on the surfaces and, as we have shown, the latter group (mechanoradicals) stabilizes the charged species. Previously, in our group, it was shown that by removing the mechanoradicals with radical scavenger antioxidants one can destabilize the charges – doping with antioxidants makes materials antistatic. However, the scavenger antioxidants we had used in this example to show the antistatic behavior were far from being practical in use for general polymers -that are produces in millions of tons per year- because of their individual prices. Lignin is the world’s second most abundant polymer. It has antioxidant properties, so it is a good candidate as an antistatic agent for common polymers. In this study we assess the lignin’s antistatic action by doping it into common polymers - elastomers (silicon rubber) and thermoplastics (PE, PP, PVC), and comparing the accumulated net charge on the doped and undoped polymers upon contact electrification. It was shown that the increase in lignin concentration and decrease in particle size of the lignin enhances the antistatic property in the polymers, due to an increase in radical scavenging OH groups, as verified by 31P-NMR analysis. We certify that the antistatic property is because of the radical scavenging action and not by increase in the surface conductivity. By doping polymers with cheap and abundant lignin, we provide a more universal, environment-friendly method for preventing electrostatic charge accumulation on common polymers, which are produced in millions of tons per year.
Open Access
Organic charge transfer cocrystals as additives for dissipation of contact charges on polymers
(American Chemical Society, 2022-12-06) Ekim, Sunay Dilara; Kaya, Görkem Eylül; Daştemir, M.; Yildirim, E.; Baytekin, H. T.; Baytekin, Bilge
Common polymers can accumulate surface charges through contact, a phenomenon known since ancient times. This charge accumulation can have detrimental consequences in industry. It causes accidents and yields enormous economic losses. Many empirical methods have been developed to prevent the problems caused by charge accumulation. However, a general chemical approach is still missing in the literature since the charge accumulation and discharging mechanisms have not been completely clarified. The current practice to achieve charge mitigation is to increase materials conductivity by high doping of conductive additives. A recent study showed that using photoexcitation of some organic dyes, charge decay can be started remotely, and the minute amount of additive does not change the material's conductivity. Here, we show the contact charging and charge decay behavior of polydimethylsiloxane doped with a series of organic charge transfer cocrystals (CTC) of TCNQ acceptor and substituted pyrene donors (CTC-PDMS). The results show that the CTC-PDMS are antistatic, and the discharging propensity of the composites follows the calculated charge transfer degree of the complexes. On the other hand, the CTC-PDMS are still insulators, as shown by their high surface resistivities. Kelvin probe force microscopy images of the contact-charged and discharged samples show a quick potential decay in CTC domains upon illumination. Combined with the fast overall decay observed, the antistatic behavior in these insulators can be attributed to an electron transfer between the mechanoions in the polymer and the CTC frontier orbitals. We believe our results will help with the general understanding of the molecular mechanism of contact charging and discharging and help develop insulator antistatics.