History of the most soft! Tear novel, self-healing flexible semiconductor!
For decades, bulky portable electronic devices become increasingly compact, scalable and flexible electronic monitoring device health and development in areas such as artificial skin faster, semiconducting polymers for its excellent chemical adjustable, solution processing and mechanical deformation of gradually been widely used in these areas, greatly promoted the development of next-generation wearable devices. However, subject to the inherent rigidity of semiconducting polymer backbone and a molecular weight limit, which is higher than the modulus of elasticity of the human skin generally, the hysteresis loop when a strong stretching effect, leading to the wearable device and the mechanical properties of human skin between the electrodes does not match, equipment is a potential problem from buckling and delamination soft skin.
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Recently, professor at University of Southern Mississippi Guxiao Dan reported a room from the semiconductor and tear healing composite film, the composite film of a conjugated polymer and butyl rubber (BR) elastomer , not only exhibits unprecedented low elastic modulus (<1 MPa）和超高变形性，而且断裂应变超过800％，并通过物理接触实验证明了该复合膜的自愈合能力。此外，由于BR具有对氧气和水的阻隔性，复合膜显示出超过5个月的高稳定性，可用于制造模拟人类皮肤的抗撕裂性和可愈合特性的新型弹性电子器件！
tear and self-healing composite membrane structure
As shown, the researchers used an excellent elasticity and excellent oxygen and water the barrier properties of butyl rubber (BR) as elastomeric base, selected to have a high charge mobility PDPPTVT as donor polymers can be produced having a tear resistance and healing composite film.
PDPPTVT / BR composite membrane deformability test
low deformability PDPPTVT original film shown in FIG. 2 contrast, FIG. 3 PDPPTVT / BR composite membrane exhibited an unprecedented low elastic modulus and high strain at break over 800%, showing a conventional semiconductor composite lowest and highest modulus of deformability.
[ 123] FIG. 2. tensile test PDPPTVT film
FIG 3. PDPPTVT / BR composite film tensile testPDPPTVT / BR tear resistance of the composite film
subsequently, researchers use the edges of the film notched tear resistance test shown, the original rupture quickly PDPPTVT 4; while PDPPTVT / BRThe composite film is not completely broken even at 100% strain, which is due to the highly entangled polymer chains may BR strand slippage and breakage resistance, greatly improve the mechanical properties of the conjugated polymer, the composite membrane having a high strain cracking and excellent tear resistance.
Figure 4. tearable film of Comparativeelectrical properties PDPPTVT / BR composite film
Next, the researchers composite film electrical performance testing, to explore the application of a flexible electronic device of the composite membrane. When the composite film is first stretched to the desired strain, and then manufacturing an organic field-effect transistors (OFETs), as shown, the composite film is applied at 150 percent strain in two directions 5 charge transport, charge carrier mobility is not change significantly even proved that the composite membrane is still a strong electrical properties at a strain state.
FIG. 5. PDPPTVT / electrical properties of the composite film characterized BRStability PDPPTVT / BR composite film
Since the electrical properties of the organic semiconductor material is usually rapidly degraded under conditions of oxygen and water, the researchers explored the stability PDPPTVT / BR OFET devices made at different strain composite film under ambient conditions, the results shown in Figure 6, is stored under ambient conditions for more than 150 days later, charge carrier mobility of only shown limited degradation, indicating that the composite film has excellent stability.
Figure 6 based on the electrical mobility of charge carriers OFET device composite filmSelf-healing PDPPTVT / BR composite membrane performance
Subsequently, studies We tested the PDPPTVT / BR self-healing properties of the composite film at room temperature. 7 and 8, the two sheets of composite films in contact and compresses, 2 seconds after stretching, it is apparent that a composite film adhered to each other automatically in the compression process, the film may be stretched beyond its original healing 150% of the length. And FIG PDPPTVT film 9 does not show any sign of healing is confirmed excellent self-healing properties of the composite film.
Figure 7 a schematic view of the self-healing process
FIG. 8. PDPPTVT / BR test self-healing composite film
FIG 9. PDPPTVT film self-healing test
FIG self-healing composite film 10. After different cycles of charge carrier mobility