Thickness Dependence of the Young’s Modulus of Polymer Thin Films

Chang, Jooyoung; Toga, Kamil; Paulsen, Joseph D.; Menon, Narayanan; Russell, Thomas P.

doi:10.1021/acs.macromol.8b00602

Cited by 52 publications

(49 citation statements)

References 59 publications

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“…The bulk, Young's and shear moduli and Poisson's ratio of AGX are shown as solid dots in Fig. 2d, e. The bulk and shear moduli are difficult to measure experimentally, as samples are usually prepared in the form of thin films (Chang et al 2018). Available reports, mostly about Young's moduli at 27°C and 50% RH, agree well with our simulation which is about 2.5 GPa under similar temperature and moisture level (Gröndahl et al 2004;Höije et al 2005;Escalante et al 2012).…”

Section: Resultssupporting

confidence: 85%

Moisture-induced crossover in the thermodynamic and mechanical response of hydrophilic biopolymer

et al. 2019

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The use of natural sustainable resources such as wood in green industrial processes is currently limited by our poor understanding of the impact of moisture on their thermodynamic and mechanical behaviors. Here, a molecular dynamics approach is used to investigate the physical response of a typical hydrophilic biopolymer in softwood hemicellulosexylan-when subjected to moisture adsorption. A unique moisture-induced crossover is found in the thermodynamic and mechanical properties of this prototypical biopolymer with many quantities such as the heat of adsorption, heat capacity, thermal expansion and elastic moduli exhibiting a marked evolution change for a moisture content about 30 wt%. By investigating the microscopic structure of the confined water molecules and the polymer-water interfacial area, the molecular mechanism responsible for this crossover is shown to correspond to the formation of a double-layer adsorbed film along the amorphous polymeric chains. In addition to this moisture-induced crossover, many properties of the hydrated biopolymer are found to obey simple material models.

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Section: Resultssupporting

confidence: 85%

Moisture-induced crossover in the thermodynamic and mechanical response of hydrophilic biopolymer

et al. 2019

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“…For example, wrinkle wavelengths around λ≈4.7 normalμnormalm were used in ref. 38 to focus light; our model suggests that extremely thin (h∼7 normalnnormalm) PS sheets (39) would generate wrinkles with similar wavelengths over a fraction of a millisecond. Many optical applications, including photonic materials (40) and Bragg gratings (41), require periodic structures with period comparable with the wavelength of visible light.…”

mentioning

confidence: 89%

Dynamics of wrinkling in ultrathin elastic sheets

Box

O’Kiely

Kodio

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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The wrinkling of thin elastic objects provides a means of generating regular patterning at small scales in applications ranging from photovoltaics to microfluidic devices. Static wrinkle patterns are known to be governed by an energetic balance between the object’s bending stiffness and an effective substrate stiffness, which may originate from a true substrate stiffness or from tension and curvature along the wrinkles. Here, we investigate dynamic wrinkling induced by the impact of a solid sphere onto an ultrathin polymer sheet floating on water. The vertical deflection of the sheet’s center induced by impact draws material radially inward, resulting in an azimuthal compression that is relieved by the wrinkling of the entire sheet. We show that this wrinkling is truly dynamic, exhibiting features that are qualitatively different to those seen in quasistatic wrinkling experiments. Moreover, we show that the wrinkles coarsen dynamically because of the inhibiting effect of the fluid inertia. This dynamic coarsening can be understood heuristically as the result of a dynamic stiffness, which dominates the static stiffnesses reported thus far, and allows control of wrinkle wavelength.

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“…Thus far, poly(methyl methacrylate) (PMMA) and polydimethylsiloxane (PDMS) are the two most commonly used materials for the dielectric layer. As the PMMA features a high Young's modulus (≈3 GPa), its rigidity is large and it is difficult to deform under tiny pressure, which will lead to low sensitivity of the sensor. More importantly, it also affects the flexibility of the sensor, which is limited in the application of wearable devices .…”

Section: Introductionmentioning

confidence: 99%

Highly Morphology‐Controllable and Highly Sensitive Capacitive Tactile Sensor Based on Epidermis‐Dermis‐Inspired Interlocked Asymmetric‐Nanocone Arrays for Detection of Tiny Pressure

Niu

Gao

Yue

et al. 2019

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The tactile sensor lies at the heart of electronic skin and is of great importance in the development of flexible electronic devices. To date, it still remains a critical challenge to develop a large-scale capacitive tactile sensor with high sensitivity and controllable morphology in an economical way. Inspired by the interlocked microridges between the epidermis and dermis, herein, a highly sensitive capacitive tactile sensor by creating interlocked asymmetric-nanocones in poly(vinylidenefluorideco-trifluoroethylene) film is proposed. Particularly, a facile method based on cone-shaped nanoporous anodized aluminum oxide templates is proposed to cost-effectively fabricate the highly ordered nanocones in a controllable manner and on a large scale. Finite-element analysis reveals that under vertical forces, the strain/stress can be highly strengthened and localized at the contact apexes, resulting in an amplified variation of film permittivity and thickness. Benefiting from this, the developed tactile sensor presents several conspicuous features, including the maximum sensitivity (6.583 kPa −1 ) in the low pressure region (0-100 Pa), ultralow detection limit (≈3 Pa), rapid response/recovery time (48/36 ms), excellent stability and reproducibility (10 000 cycles). These salient merits enable the sensor to be successfully applied in a variety of applications including sign language gesture detection, spatial pressure mapping, Braille recognition, and physiological signal monitoring. Keywords anodized aluminum oxide, capacitive tactile sensors, electronic skin, highly morphology-controllable, interlocked asymmetric-nanocone arrays, P(VDF-TrFE)

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Thickness Dependence of the Young’s Modulus of Polymer Thin Films

Cited by 52 publications

References 59 publications

Moisture-induced crossover in the thermodynamic and mechanical response of hydrophilic biopolymer

Moisture-induced crossover in the thermodynamic and mechanical response of hydrophilic biopolymer

Dynamics of wrinkling in ultrathin elastic sheets

Highly Morphology‐Controllable and Highly Sensitive Capacitive Tactile Sensor Based on Epidermis‐Dermis‐Inspired Interlocked Asymmetric‐Nanocone Arrays for Detection of Tiny Pressure

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