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Sensors with accurate detection of various liquids have attracted increasing research interests in environmental protection and organic solvents transporation. In this paper, liquid sensor based on laser induced graphene paper (LIGP) was proposed, and successfully used for the rapid detection of micro volume liquid. The processing-structure-property relationship was systemically studied. LIGPs with different morphologies exhibited various sensitivities and showed good reproducibility and fast response. The response mechanism related to contact resistance between some adjacent graphene flakes/fibers was proposed. With the key findings, LIGP liquid sensors can be used as the detector for accurate identification of different solvents and have great potential in monitoring organic solvent leakages of pipelines and fabrication of smart anti-corrosion composite structures.

Smart, deformable, and transparent electrodes are a significant part of flexible optoelectronic devices. In this work, a novel approach to making highly transparent, smooth, and conductive shape memory polyimide hybrids has been proposed. Colorless shape memory polyimide (CSMPI) with high optical transparency and high heat resistance is served as the substrate for flexible electronic devices for the first time. A hybrid (Au/Ag) metal grid electrode embedded in CSMPI (BMG/CSMPI) is first fabricated via self-cracking template and solution-coating, the advantages of which include ultrasmooth surface, superior mechanical flexibility and durability, strong surface adhesion, and excellent chemical stability due to the unique embedded hybrid structure. The resulting white polymer light emitting diodes (WPLEDs) based on BMG/CSMPI with shape memory effect are active and deformable, and are converted from 2D device into 3D devices depending on its variable stiffness characteristics. The deformed 3D devices could actively recover to the original shape upon heating. Furthermore, ultrathin and flexible 3D optoelectronic devices fabricated using shape memory polymers can promote the development of advanced optoelectronic applications in the future.

Colorless shape memory polyimide (CSMPI) has potential applications in broad fields, especially in advanced optoelectronics due to the excellent optical transparency, shape memory effect and high temperature resistance. In this work, CSMPI prepared by high flexible dianhydrides and fluorine-containing diamines has excellent optical transparency, shape memory properties and high temperature resistance. High flexible dianhydrides that makes the molecule chains more easily twisted and tangled to form physical crosslinking points is favorable for possessing great shape memory property. The fluorine-containing diamines effectively destroyed the highly conjugated molecular structure and inhibited the formation of CTC, ensuring the CSMPI with excellent optical transparency. The effects of monomer ratio and imidization temperature on the molecular structure and properties were discussed. The CSMPI film possesses a higher glass transition temperature (Tg) of 234 °C, compared to the reported transparent shape memory polymers (SMPs). Most importantly, the transmittance of CSMPI film is 87~90% at 450~800nm, meeting the requirements of heat resistance and transmittance of the substrate. Both shape recovery and shape fixity are over 97%. Flexible and colorless CSMPI films has potential applications in broad fields, especially in advanced optoelectronics, such as flexible substrates for OLED and OPV devices, etc.

The current electroactive shape memory polymer composites (SMPCs) show low electric heating efficiency, and the transparency of the matrix is seriously damaged by the conductive fillers. In this work, transparent metal mesh is used to replace the conductive fillers to construct a conductive network for electrical actuation for the first time. The self-cracking aluminum mesh is embedded in the transparent shape memory polyimide film (Alm@TSMPI) by solution casting. As a new type of flexible and transparent heater, the Alm@TSMPI has advantages of fast response and high steady-state temperature. As an electric actuator, the Alm@TSMPI is active and deformable depending on its variable stiffness characteristics, and reverts to its original shape within 13 s under electric stimulation. This is the first report on an electroactive transparent shape memory polymer while maintaining light transmission. Moreover, the transition temperature of 230 °C is much higher than that of all other reported electroactive SMPCs. Furthermore, the Alm@TSMPI is attached to transparent shape memory polystyrene as a flexible transparent heater, and the deformation is triggered by electric field. According to this strategy, the Alm@TSMPI can be applied for the electrical actuation of other SMPs, extending the applications in the electric actuators.

Colorless shape memory polyimide (CSMPI) has potential applications in broad fields, especially in advanced optoelectronics due to the excellent optical transparency, shape memory effect and high temperature resistance. In this work, high flexible dianhydrides and fluorine-containing diamines were used to synthesize CSMPI, which simultaneously combined great shape memory performance with high optical transparency. The effects of monomer ratios and imidization temperatures on the molecular structure and properties were investigated. Moreover, the CSMPI film possesses a higher glass transition temperature (T g) of 234 °C, compared with the reported transparent shape memory polymers. Most importantly, the transmittance of CSMPI film is 87%–90% at 450–800 nm, meeting the requirements of heat resistance and transmittance of the substrate. Both shape recovery and shape fixity are over 97%. Flexible and colorless CSMPI films severed as substrates provide more potential in optoelectronic devices such as OLED and OPV, etc.