Dramatic increase in polymer triboelectrification by transition from a glassy to rubbery state

Adv Materials Technologies

Lapčinskis

Verners

et al. 2022

Self Cite

researchers aim to magnify the triboelectric charge on polymer surfaces. Polymer triboelectrification can be enhanced in several ways, including surface functionalization, [8] adjustment of the electronic and physicochemical properties between contacting materials, [9][10][11][12][13][14][15] or by increasing the specific contact area via nanostructuring. [16,17] Surface contact electrification can be observed also in nature. Spider ballooning is one of the most exciting natural phenomena. Using electrified strands of silk, [18] spiders can travel in the airstream for distances of hundreds of kilometers. [19] Spider silk is electrified due to contact and friction with airborne particles or during the spinning process. [20] To ensure the electrostatic flight, holding the weight of a spider, even in the absence of any aerodynamic lift, a strong surface charge is required.To understand how silk achieves this strong surface charge, understanding of its macromolecular structure is required. Spider silk has a hierarchical structure composed of highly ordered macromolecular inclusions which are interconnected by disordered elastomeric chains. [21] This macromolecular structure may lead to stress concentration, which we hypothesize is (partially) responsible for the strong surface charge.Recently, it has been found that the surface electrification of polymers is strongly connected to their physicochemical Triboelectrification of polymers enables mechanical energy harvesting in triboelectric generators, droplet generators, and ferroelectrets. Herein, triboelectric polymers, inspired by the ordering in spider-silk, with strongly enhanced contact electrification are presented. The ordering in polyether block amide (PEBA) is induced by the addition of inorganic goethite (α-FeOOH) nanowires that form H-bonds with the elastomeric matrix. The addition of as little as 0.1 vol% of α-FeOOH into PEBA increases the surface charge by more than order of magnitude (from 0.069 to 0.93 nC cm -2 ). The H-bonds between α-FeOOH and PEBA promote the formation of inclusions with higher degree of macromolecular ordering, analogous to the structure of spider silk. The formation of these inclusions is proven via nanoindentation hardness measurements and correlated with H-bond-induced chemical changes by Fourier transform infrared spectroscopy and direct scanning calorimetry. Theoretical studies reveal that the irregularity in hardness provides stress accumulation on the polymer surface during contactseparation. Subsequent molecular dynamic studies demonstrate that stress accumulation promotes the mass-transfer mechanism of contact electrification. The proposed macromolecular structure design provides a new paradigm for developing materials for applications in mechanical energy harvesting.

Section: Introductionmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Bio‐Inspired Macromolecular Ordering of Elastomers for Enhanced Contact Electrification and Triboelectric Energy Harvesting

Adv Materials Technologies

Lapčinskis

Verners

et al. 2022

Self Cite

“…There are many studies that show the stable performance of TENG devices over the thousands of cycles driven by triboelectric surface charge. [ 4,28 ]…”

Section: Resultsmentioning

confidence: 99%

Triboelectric Laminates with Volumetric Electromechanical Response for Mechanical Energy Harvesting

Adv Materials Technologies

Mālnieks

Linarts

et al. 2021

Self Cite

The main requirement for triboelectric nanogenerator devices is the necessity to have separable or movable parts to harvest mechanical energy, thus complicating their integration into the energy harvesting systems. Herein, triboelectric laminates that show a volumetric electromechanical response are introduced, similar to intrinsic ferroelectric polymers. The laminates are composed of stacked bilayer polymer films with different triboelectric surface properties separated by polymer mesh. This sophisticated design provides dipole alignment across the volume of triboelectric laminate and electromechanical response without applying any poling procedure. Triboelectric laminate generates the open‐circuit voltage (VOC) of 29 V and short‐circuit current (ISC) of 15 nA. Volumetric energy density of 21.13 µJ cm−3 and a peak average power density of 46.19 µW cm−3 are observed. Triboelectric laminate shows an effective piezoelectric constant d33 of 9.83 pC N−1, higher than reported for piezoelectric polymer like nylon‐11. The triboelectric laminate is produced from cheap, mechanically flexible materials that can be produced in large quantities.

Engineering Polymer Interfaces: A Review toward Controlling Triboelectric Surface Charge

Lapčinskis

et al. 2023

Adv Materials Inter

Self Cite

Contact electrification and triboelectric charging are areas of intense research. Despite their low ability to accept or donate electrons, polymer insulator based triboelectric nanogenerators have emerged as highly efficient mechanical‐to‐electrical conversion devices. Here, it is reviewed the structure–property–performance of polymer insulators in triboelectric nanogenerators and focus on tools that can be used to directly enhance charge generation, via altering a polymer's mechanical, thermal, chemical, and topographical properties. In addition to the discussion of these fundamental properties, the use of additives to locally manipulate the polymer surface structure is discussed. The link between each property and the underlying charging mechanism is discussed, in the context of both increasing surface charge and predicting the polarity of surface charge, and pathways to engineer triboelectric charging are highlighted. Key questions facing the field surrounding data reporting, the role of water, and synergy between mass, electron, and ion transfer mechanisms are highlighted with aspirational goals of a holistic model for triboelectric charging proposed.