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Conjugated polymers have been well-known as a critical candidate for stretchable electronics applications. However, further research is still needed to fully understand what kind of film morphology is beneficial to keep the charge mobility under cycling deformation. Herein, we proposed that the co-deformation of crystalline domains and amorphous regions can effectively dissipate strain energy. To verify our idea, we developed three kinds of the morphology of a diketopyrrolopyrrole-based polymer (DPP-TVT) with different crystallinity by changing the interaction parameter between solvent and sidechain (R a solvent-sidechain). The films cast from TCB with medium crystallinity exhibited 100% mobility retention (0.42 cm2V−1s−1) under 100% strain and after 100 stretch-release cycles at 50% strain. However, the mobility of CN films with high crystallinity decreased from 0.45 to 0.23 cm2V−1s−1 under a single stretch at 100% strain, while the performance of CF films with low crystallinity decreased from 0.34 to 0.052 cm2V−1s−1 after 100 stretch-release cycles at 50% strain. The optimized performance of TCB films stems from the fact that the dispersed crystallites embedded in the amorphous matrix provide an efficient and robust charge transport network under single and repeating deformation. This research would aid in manipulating the mechanical and electrical properties of conjugated polymers. [Display omitted] • Simply solvent processing. • High fatigue resistance. • Crystallinity-stretchability relation. [ABSTRACT FROM AUTHOR]

The development of self-healing elastomers with superior physical properties is a challenging task. Herein, we present a design concept for a self-healing, highly stretchable, and robust poly(urethane–urea) elastomer prepared via a thiol-ene click reaction by a facile one-pot in situ photopolymerization method. The objective of the utilized approach is to incorporate weak noncovalent H-bonds, dynamic covalent urea bonds, and products of a thiol-ene click reaction into a polymeric backbone. This study also applies polytetramethylene ether glycol domains as soft segments to facilitate the polymeric chain diffusion and dynamic exchange reaction. Owing to these unique molecular characteristics, the resultant elastomer possesses a uniform structure and versatile properties, such as high stretchability corresponding to a maximum strain of 464%, ultimate tensile strength of 10.9 MPa, self-recoverability, high self-healing efficiency of 99%, high recyclability, and good weldability. Upon rupture, the as-prepared elastomer completely restores its original mechanical properties after heating to 80 °C for 5 h. The dynamic reversibility of the elastomer is evidenced by stress relaxation analysis and rheological testing. In addition, it can be effectively encapsulated and potentially used for fabricating self-healing stretchable conductive devices. • Self-healing poly(urethane–urea) elastomer is prepared by photopolymerization. • The obtained elastomer possesses a uniform structure and versatile characteristics. • Ruptured poly(urethane–urea) elastomer easily restores its mechanical properties. • The poly(urethane-urea) elastomer shows potential in self-healing stretchable conductive devices. [ABSTRACT FROM AUTHOR]

The development of the information technology and, very recently, of new application scenarios like Internet of Things (IoT) and Industry 4.0 has pushed the research towards new technological platforms. In this frame, the spatial freedom permitted by flexible short-range connections and flexible devices has become as important as "classical" parameters such as low weight, low power consumption, and electromagnetic immunity. Accordingly, first the flexible electronics and later the flexible photonics have produced innovative components and devices. The present paper aims at presenting a brief overview of this broad area, underlining the achievements and the remaining challenges in the different routes to the manufacturing of flexible photonic devices. Material platforms remain at the core of such developments, and it is interesting to note that glassy materials still constitute a fundamental piece in the present and future scenario. • A short summary of the early steps of flexible electronics is presented. • Early developments of flexible photonics are discussed. • Various material platforms of flexible photonics are reviewed: ∙ Semiconductor on polymer flexible structures ∙All-polymeric structures ∙Glass on polymer structures ∙Flexible glass substrates and components • Further potential developments are outlined [ABSTRACT FROM AUTHOR]

Bionic integrated sensing devices with numerous distributed electronic elements substantially expand the human's interactive control capabilities. Several difficulties need to be overcome, including intricate interconnections, complicated structures, and electromagnetic interference/compatibility in signal transmission. In addition, retention of device's functionalities under high deformation is desired, while it faces huge challenges to achieve stretchability and deformation insensitivity. Herein, a highly stretchable and deformation-insensitive bionic electronic exteroceptive neural sensor is first presented and fabricated from the functional composite of polyester thread coated with carbon nanotubes. The bionic electronic exteroceptive neural sensor features all-in-one bionic multifunctional characteristics, which effectively avoids the use of numerous distributed electronic elements. Importantly, it achieves high stretchability and characterizes unprecedented deformation-insensitive functional property. The properties enable the bionic electronic exteroceptive neural sensor to serve as a wearable device and function continuously without interference even when being greatly stretched (100% strain). Other prominent advantages of the bionic electronic exteroceptive neural sensor are excellent stability (> 15,000 cyclical tests), rapid response (≤ 15 ms), high robustness, geometrically hierarchical sensing, and personalized cuttability. The tremendous potential applications of the bionic electronic exteroceptive neural sensor are demonstrated in the fields of human-machine interactions, information security system, and Internet of things. ga1 • A stretchable and multifunctional all-in-one electronic exteroceptive sensor is demonstrated by using carbon nanotubes@polyester thread. • The stretching insensitivity of the electronic exteroceptive sensor is first achieved, which enables device to operate efficiently and steadily even when being largely deformed (100% strain). • The stretchable bionic synaptic plasticity of the electronic exteroceptive sensor is first demonstrated, revealing the device's enormous potential for sophisticated human-machine interactions and neuroprosthetics. • Ultra-robustness to different mechanical stimulations, cuttability, and excellent durability against > 15,000 repetitive stimulations are the important stable characteristics of the electronic exteroceptive sensor • Geometrically hierarchical sensing, spatiotemporal resolution function, and rapid response (≤ 15 ms) endow the great potential of the electronic exteroceptive sensor for multifunctional touch interactions [ABSTRACT FROM AUTHOR]