ABSTRACT
The visualization and analysis of organic solvents using fluorescent sensors are crucial, given their association with environmental safety and human health. Conventional fluorescent sensors are typically single-use sensors and they often require sophisticated measurement instruments, which limits their practical and diverse applications. Herein, we develop solvatochromic nitrogen and sulfur codoped carbon dots (NS-CDs)-based organogel sensors that display color changes in response to different solvents. NS-CDs are synthesized using a solvothermal method to produce monodispersed particles with exceptional solubility in various organic solvents. NS-CDs exhibit distinct photoluminescent emission spectra that correlate with the solvent polarity, and the solvent-dependent photoluminescent mechanism is investigated in detail. To highlight the potential application of solvatochromic NS-CDs, portable and low-cost NS-CDs-embedded organogel sensors are fabricated. These sensors exhibit highly robust solvatochromic performance despite repeated solvent switches, thus ensuring consistent and reliable measurements in practical applications. This study provides valuable insights into the solvatochromism of carbon dots and opens up new avenues for designing real-time organic solvent sensing platforms.
Subject(s)
Carbon , Quantum Dots , Humans , Solvents , Sulfur , Coloring Agents , NitrogenABSTRACT
Because electronics are becoming flexible, the demand for techniques to manufacture thin flexible printed circuit boards (FPCBs) has increased. Conventional FPCBs are fabricated by attaching a coverlay film (41 µm) onto copper patterns/polyimide (PI) film to produce the structure of coverlay/Cu patterns/PI film. Given that the conventional coverlay consists of two layers of polyimide film and adhesive, its thickness must be reduced to generate thinner FPCBs. In this study, we fabricated 25-µm-thick poly(amide-imide-urethane)/epoxy interpenetrating networks (IPNs) to replace the thick conventional coverlay. Poly(amide-imide-urethane) (PAIU) was synthesized by reacting isocyanate-capped polyurethane with trimellitic anhydride and then mixed with epoxy resin to produce PAIU/epoxy IPNs after curing. Thanks to the soft segments of polyurethane, the elongation of PAIU/epoxy IPNs increased with increasing PAIU content and reached over 200%. After confirming the excellent thermal stability and chemical resistance of the PAIU/epoxy IPNs, we fabricated FPCBs by equipping them as coverlays. The mechanical durability of the FPCBs was evaluated through an MIT folding test, and the FPCB fabricated with PAIU/ep-2 was stable up to 164 folding cycles because of the balanced mechanical properties.
ABSTRACT
Utilizing a newly programmed and synthesized heat storage mesogen (HSM) and reactive mesogen (RM), advanced heat managing polymer alloys that exhibit high thermal conductivity, high latent heat, and phase transition at high temperatures were developed for use as smart thermal energy harvesting and reutilization materials. The RM in the heat-managing RM-HSM polymer alloy was polymerized to form a robust polymeric network with high thermal conductivity. The phase-separated HSM domains between RM polymeric networks absorbed and released a lot of thermal energy in response to changes in the surrounding temperature. For the fabrication of smart heat-managing RM-HSM polymer alloys, the composition and polymerization temperature were optimized based on the constructed phase diagram and thermal energy managing properties of the RM-HSM mixture. From morphological investigation and thermal analysis, it was realized that the heat storage capacity of polymer alloys depends on the size of the phase-separated HSM domain. The structure-morphology-property relationship of the heat managing polymer alloys was built based on the combined techniques of thermal, scattering, and morphological analysis. The newly developed mesogen-based polymer alloys can be used as smart thermal energy-harvesting and reutilization materials.
ABSTRACT
(Bi2Te3)(1-x)(PbTe)(x) binary systems near eutectic composition were prepared by melting of elemental metals and a sequential water quenching process and their microstructures and thermoelectric properties were investigated. Multiple phases such as Bi2Te3, BiPbTe and PbTe were observed due to phase separation when the composition x was higher than the eutectic point. Also the electrical conduction type of the alloys converted from p-type to n-type in the phase separated alloys. The lattice thermal conductivities in the phase-separated alloys are lower than those in alloys without phase separation, attributable to increased boundary scattering.
