Interface Engineered Microcellular Magnetic Conductive Polyurethane Nanocomposite Foams for Electromagnetic Interference Shielding

Lightweight microcellular polyurethane(TPU)/carbon nanotubes(CNTs)/nickel-coated CNTs(Ni@CNTs)/polymerizable ionic liquid copolymer(PIL)composite foams are prepared by non-solvent induced phase separation(NIPS).CNTs and Ni@CNTs modified by PIL provide more heterogeneous nucleation sites and inhibit the aggregation and combination of microcellular structure.Compared with TPU/CNTs,the TPU/CNTs/PIL and TPU/CNTs/Ni@CNTs/PIL composite foams with smaller microcellular structures have a high electromagnetic interference shielding effectiveness(EMI SE).The evaporate time regulates the microcellular structure,improves the conductive network of composite foams and reduces the microcellular size,which strengthens the multiple reflections of electromagnetic wave.The TPU/10CNTs/10Ni@CNTs/PIL foam exhibits slightly higher SE values(69.9 dB)compared with TPU/20CNTs/PIL foam(53.3 dB).The highest specific EMI SE of TPU/20CNTs/PIL and TPU/10CNTs/10Ni@CNTs/PIL reaches up to 187.2 and 211.5 dB/(g cm^(−3)),respectively.The polarization losses caused by interfacial polarization between TPU substrates and conductive fillers,conduction loss caused by conductive network of fillers and magnetic loss caused by Ni@CNT synergistically attenuate the microwave energy.

Wide tunable laser based on electrically regulated bandwidth broadening in polymer-stabilized cholesteric liquid crystal

Electrically responsive photonic crystals represent one of the most promising intelligent material candidates for technological applications in optoelectronics. In this research, dye-doped polymer-stabilized cholesteric liquid crystals(PSCLCs) with negative dielectric anisotropy were fabricated, and mirrorless lasing with an electrically tunable wavelength was successfully achieved. Unlike conventional liquid-crystal lasers, the proposed laser aided in tuning the emission wavelength through controlling the reflection bandwidth based on gradient pitch distribution. The principal advantage of the electrically controlled dye-doped PSCLC laser is that the electric field is applied parallel to the helical axis, which changes the pitch gradient instead of rotating the helix axis, thus keeping the heliconical structure intact during lasing. The broad tuning range(～110 nm) of PSCLC lasers,coupled with their stable emission performance, continuous tunability, and easy fabrication, leads to its numerous potential applications in intelligent optoelectronic devices, such as sensing, medicine, and display.

Band-gap-tailored random laser

A band-gap-tailored random laser with a wide tunable range and low threshold through infrared radiation is demonstrated. When fluorescent dyes are doped into the liquid crystal and heavily doped chiral agent system,we demonstrate a wavelength tuning random laser instead of a side-band laser, which is caused by the combined effect of multi-scattering of liquid crystal(LC) and band-gap control. Through rotating the infrared absorbing material on the side of the LC cell, an adjustable range for random lasing of 80 nm by infrared light irradiation was observed.