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The rapid development of flexible transparent electronic devices puts forward more requirements for substrate materials, not only including high transparency, but also possessing good self-healing ability, high mechanical strength and toughness. Herein, a urea-containing chain-extended polydimethylsiloxane (LPx) was first designed and synthesized to construct dynamic physical crosslinks induced by hydrogen bonds. Subsequently, multi-amino terminated hyperbranched polysiloxane (HPSi) was selected as the permanent chemical crosslinking point and connected with LPx through isocyanate with controlled exchangeable aliphatic disulfide (SS-NCO). Consequently, a series of LPx-SS-HP films with hierarchical crosslinked networks and dual dynamic bonds are developed. The chain-extension degree of LPx has been proved to play a key role in adjusting the mechanical, thermal and self-healing properties. Among the serial films, LP2-SS-HP shows the best comprehensive properties, of which the glass transition temperature (Tg), tensile strength, Young's modulus and toughness are as high as 96 °C, 8.6 ± 0.6 MPa, 188.5 ± 11.2 MPa and 16.3 ± 0.2 MJ m−3, respectively. Besides, its outstanding flexibility could generate reversible shape changes from folding to bending and scrolling. After three scratching-healing cycles, the healing efficiency of LP2-SS-HP at the same location is still above 90% and the transmittance at 550 nm is as high as 88.6%. These remarkable properties demonstrate that LP2-SS-HP is a high performance scrollable and foldable substrate for fabricating transparent healable electrodes.

Developing a multi-functional coating with high mechanical strength, and reversible self-healing and antibacterial ability has become an effective strategy for preventing the severe threat to human health posed by biofilm contamination. Herein, a novel linear polyacrylate resin (LP) containing pendent sulfobetaine and acetoacetyloxy groups was designed and synthesized, and was subsequently reacted with hyperbranched polysiloxane terminated by multi-amine (HPSi) to form dynamic vinylogous urethane groups. The resultant novel multi-functional crosslinked polyacrylate coating (LP-HP) shows high mechanical strength, and outstanding reversible self-healing and remarkable antibacterial ability. The concentration of HPSi in the polyacrylate coating is systematically researched and proved to play a key role in adjusting the mechanical, thermal and self-healing properties. For the polyacrylate coating (LP-HP6) containing 6.3 wt% of HPSi, its tensile strength and toughness are as high as 17.89 ± 0.42 MPa and 5.72 ± 0.32 MPa, respectively. The self-healing efficiency of LP-HP6 is higher than 92% under mild conditions (maintained at 60 °C for 24 h). This is ascribed to the unique configuration of HPSi that is rich in amine groups and has fewer chain entanglements to facilitate easier segmental motion. Furthermore, the surface of LP-HP6 exhibits high resistance to the adhesion of E. coli and S. aureus with antibacterial rates above 95%, originated from the nonspecific and nontoxic sulfobetaine groups immobilized in the main chain via convenient copolymerization. These excellent properties demonstrate that LP-HP coatings have great potential applications to resist biofilm contamination in architectural ornament, medical engineering, food and pharmaceutical fields.

In the past several decades, a great deal of attention has been focused on the control of light emission of luminescent materials. Compared to our previous work on an aggregation-induced emission (AIE) initiator, an aggregation-caused quenching (ACQ) initiator (TPP-A) has been successfully synthesized and acted as an initiator of atom transfer radical polymerization (ATRP). Four end-functionalized polymers, PS-A, PS-NI, PNIPAM-A and PNIPAM-NI, were obtained using TPP-A or TPP-NI as an initiator via ATRP. TPP-A exhibits a weak charge transfer (CT) and ACQ, but TPP-NI possesses a strong CT and AIE. After two initiators were introduced to polystyrene (PS) chains, the CT of PS-A and PS-NI are well-preserved, but their photoluminescence (PL) intensity is increased because the PS chains could separate initiators from intermolecular interactions and restrict their intramolecular rotations. However, the emission behaviours of PNIPAM-A are different from those of PS-A due to the high polarity of the PNIPAM chain. When the temperature of the solution for PNIPAM-A is above the lower critical solution temperature (LCST), the PNIPAM-A solution possessed higher emission intensities than those measured at room temperature due to the decrease the polarity of the PNIPAM chain and the emission behaviours of PNIPAM-NI are similar to that of PS-NI.

Aggregated or solid state red fluorescent materials with efficient light emission are rare but have wide applications in optoelectronic and biological fields. Herein, two pyran derivatives, EtAmPy and EtOxPy with different charge transfers (CT), were designed as initiators and introduced to polystyrene chains via atom transfer radical polymerization (ATRP). The emission of EtAmPy was quenched both in highly polar solvents and in an aggregated state because of its strong CT and intermolecular interactions, respectively. After EtAmPy was introduced to normal polystyrene chains, the obtained functional PS emitted strong red light with a quantum yield of 37% in an aggregated state. Differently from EtAmPy, EtOxPy, possessing a weak CT and not being sensitive to the change of microenvironment, was AIE-active and displayed a large red shift in emission spectra in an aggregated state. Meanwhile, the functional PS initiated by EtOxPy showed obviously blue-shifted emission, compared to its initiator, in an aggregated state by reducing their intermolecular interactions. EtAmPy-functionalized polystyrene showed a successful application in cell imaging. Therefore, using the CT effect in molecular design and polymerization is beneficial to obtaining new red emission probes.

A new hydrazine naphthalimide initiator (NI) was designed and synthesized. Two end functional group polymers NPVCz-1 and NPVCz-2 were prepared by ATRP. We successfully controlled the location of the naphthalimide functional group at one end of the polymer chain. NPVCz-1 and NPVCz-2 were fabricated as films by simple spin-coating and all of them were then prepared as sandwich memory devices ITO/NPVCz-1/Al and ITO/NPVCz-2/Al respectively. According to the measurements, all devices exhibited stable binary flash-type memory effects. In addition, ITO/NPVCz-1/Al and ITO/NPVCz-2/Al exhibited different turn-on threshold voltages of about −2.5 and −1.5 V respectively. It illustrated that NPVCz-2 possessing a larger molecular weight shows lower turn-on threshold voltage due to the lower hole injection barrier, which was related to low-power consumption.