Free‐Standing Buckle‐Delaminated 2D Organic Nanosheets with Enhanced Mechanical Properties and Multifunctionality

Abstract

COMMUNICATION (1 of 7)Organic conjugated polymers are known as conducting polymers with tunable electronic and mechanical properties through chemical modeling and synthesis, [1] which have found broad applications in organic integrated circuits, devices, and solar cells. [2] The semiconductive polymers are often low-cost, light-weight, and flexible. These outstanding properties make it a promising candidate for organic conjugated polymer-based stretchable and multifunctional electronics and devices, [3] where both robust mechanical properties and multifunctionality are highly desired.2D organic conjugated polymer nanofilm has shown promising potential applications in organic solar cells and flexible electronics due to its tunable electronic and mechanical properties. However, its multifunctionality is largely hindered by weak mechanical performances. Here, a new strategy of harnessing buckling-driven delamination is proposed for achieving highly stretchable, free-standing organic nanosheets with largely improved multifunctionality in mechanical, electrical, and wetting properties. A model system of organic conjugated polymeric (P3BT/C60) nanosheets on prestrained elastomers is fabricated through both spin-coating and transferprinting methods. It is found that the free-standing nanosheet exhibits both superior mechanical and electrical properties with two times higher in fracture strength, and one order of magnitude higher in electrical conductivity than the spin-coated nanofilm. Compared to wrinkled spin-coated nanofilms with orthogonal cracks, the crack-free, buckle-delaminated free-standing nanosheet shows not only stable electrical properties with high stretchability but also a large enhancement in both wetting anisotropy and parallel contact angle due to its higher-aspect-ratio features. Lastly, measuring the nanofilm's fracture strength and interfacial toughness from the metrology of cracking and buckledelaminated micropatterns is demonstrated. It is shown that such metrologybased approaches can be applied to various nanofilm-substrate systems for thin film and interfacial mechanical properties measurement.

Controllable Buckle Delaminations in Polymer-Supported Periodic Gradient Films by Mechanical Compression

“…In our experiment, for a homogeneous film with h = 450 nm, the average spacing of buckle-delaminations has been measured to be d ∼ 80 μm. Then, the interfacial adhesion energy between the Ag film and the PDMS substrate is estimated to be about 1.94 J/m 2 , which is very close to the values of other metal–polymer interfaces. − Furthermore, choosing of the normal peak traction is also based on the experimental data. It can be observed experimentally that the maximum separation of the interface Δ n f is the same level as the film thickness, Δ n f = 0.5 μm.…”

“…The measurement of ψ is defined as = tan . 34 In our experiment, for a homogeneous film with h = 450 nm, the average spacing of buckle-delaminations has been measured to be d ∼ 80 μm.…”

“…We choose the following values to define the cohesive zone: , η = 0.97, T n 0 = 8 MPa, T t 0 = 3605.2 MPa, K n = 8 × 10 4 MPa/mm, and K t = 3.6 × 10 7 MPa/mm. Note that is chosen by experimental data since the interfacial adhesion energy can be estimated based on the equation . In our experiment, for a homogeneous film with h = 450 nm, the average spacing of buckle-delaminations has been measured to be d ∼ 80 μm.…”

The Effect of Liquid-Phase Exfoliated Graphene Film on Neurodifferentiation of Stem Cells from Apical Papilla

“…Great emphasis has been put on carbon nanostructured scaffolds that may display suitable characteristics for neural differentiation [13,34,38,39]. Graphene nanomaterials are carbon crystal allotropes with a two-dimensional structure and, according to data from the literature, have proven to be an excellent nanomaterial for neurodifferentiation due to their unique organization, chemical stability, exceptional mechanical properties, bactericidal potential, and biocompatibility [40,41]. This monoatomic layer of carbon shows the ability to absorb growth factors and exhibits electrical conductivity, which is of particular interest for the field of neuroscience.…”

Double‐Helical Carbon Nanotube‐Wrapped Elastomeric Mandrel for Electrical Shortage‐Free, One‐Body Multifunctional Fiber Systems

“…Conversely, no mutual current response (yellow line) of the two CNT electrodes was observed in the given voltage range; that is, complete insulation was demonstrated among the adjacent CNT electrodes even at a short distance of 600 μm. In addition to this fundamental electrical property, the advanced structural features of our DHB fiber fabricated through torsion-and strain-mismatch coupling can be summarized as follows (Figure 2c): (i) strong interfacial adhesion between the electrode and substrate originating from the torque-balance formed during the mismatch release; [48] (ii) clear discrimination between counterclockwise (defined as negative torsion) and clockwise (defined as positive torsion) twists with a resulting loose or tight double helical pattern; and (iii) effective electrode loading per unit length (i.e., high linear loading density) compared to the simple non-helical parallel configuration. We therefore expect that the resultant advanced DHB fiber would exhibit outstanding electromechanical stability, torsional sensing capability, and satisfactory linear performance values while retaining its softness and elasticity.…”