Fabrication of Highly Stretchable Conductors via Morphological Control of Carbon Nanotube Network

Abstract

Stretchable conductors, which can keep their excellent electrical conductivity while highly stretched, have been investigated extensively due to their wide range of applications in flexible and stretchable electronics, wearable displays, etc.; however, their preparation is often complicated and expensive. Herein, an efficient method to prepare high performance stretchable conductors through morphological control of conductive networks formed with carbon nanotubes (CNTs) in an elastomer matrix is reported. It is observed that an interface-mediated method could be used to align randomly oriented filler during stretching and to induce buckling of CNTs during relaxation. Further morphological studies indicate the possible formation of a wavy CNT structure induced by cyclic pre-straining. Subsequent thermal annealing is observed to collapse the oriented network and improve the local contacts between conductive networks. Through such a simple procedure, a conductivity of nearly 1000 S m(-1) and a stretchability of 200% can be achieved for composites containing 20 wt% CNTs. CNTs are observed to buckle over a large area in polymer bulk, and the combination of pre-straining and thermal annealing modifies the conductive network in the elastomer matrix. As a general method, this could be used for easy fabrication of high-performance stretchable conductors for arbitrary-shaped objects on a large scale.

Impact of geometry on stretchable meandered interconnect uniaxial tensile extension fatigue reliability

“…Reviewing the stretchable technologies developed in the recent years [3][4][5][6][7][8][9][10] we find no stretchable, conductive, composite elastomers that fulfill these requirements all at once. Only structured metals (meanders [11][12][13][14], meshes [15], yarns or buckled films [16]), forming a stretchable interconnect exhibit electro-mechanical properties that can fulfill the above mentioned requirements.…”

Strain sensing conductive polymer composites: Sensitivity and stability

“…In particular, CPCs have gained intensive attention as strain sensors for smart textiles, movement sensors, health monitoring, and wearable electronics [1][2][3][4][5][6][7][8][9][10] . In these strain sensors, the change of resistivity under strain is monitored to be used as a signal for environmental strain stimuli.…”

A highly-deformable piezoresistive film composed of a network of carbon blacks and highly oriented lamellae of high-density polyethylene

“…1-3 Composites whose electrical resistance is dependent on external pressure or tension are known as piezoresistive materials. 3,9 Thus, the modication on the particle network in polymer matrix has attracted a lot of interest. 7,8 The piezoresistive capability, such as the large strain level and the linearity relationship between the resistance change and strain, is the key property of the piezoresistive composite material, which is strongly dependent on loading type (tension, compression), loading history, especially on the particle network and the mechanical behavior of composite.…”

“…7,8 The piezoresistive capability, such as the large strain level and the linearity relationship between the resistance change and strain, is the key property of the piezoresistive composite material, which is strongly dependent on loading type (tension, compression), loading history, especially on the particle network and the mechanical behavior of composite. 5,9,[12][13][14] In fact, if the morphology could be suitably tailored, poly-olen based conductive composite would be promising candidates for the strain sensor with novel piezoresistive capability. 7,10,11 For example, introducing the accordion-like MWCNT forest structures (vertically aligned arrays of CNT bundles) into polyurethane, 10 the composite lm showed highly reversible changes in resistance in the moderate strain range (20%).…”