Xinyu Cao

The nonconventional fluorescence of amino‐functionalized polysiloxanes has received extensive attention from researchers. Protonation of the amino groups has been shown to affect polysiloxane conformation and aggregation, yet its effect on the nonconventional fluorescence remains unclear. In this study, fluorescent poly(3‐aminopropyl)silsesquioxane hydrochlorides with hexagonal structures are reported for the first time, prepared via the hydrolysis and condensation of 3‐aminopropyltrimethoxysilane with different ratios of hydrochloric acid. Regulation of the reaction pH and the associated protonation and assembly increases the fluorescence quantum yield significantly from 0.53% to 38%. The optical properties of the solution and the solid state, along with concentration‐dependent emission, confirm the fluorescence originates from clusterization‐triggered emission of amino/ammonium clusters. Comprehensive structural characterization ( ²⁹ Si NMR, FTIR, XPS, XRD) reveals that the ratio of hydrochloric acid serves as a key parameter to regulate both protonation degree and condensation pathway. This modulation promotes strong hydrogen bonding between amino and ammonium groups, yet retains suitable chain flexibility during assembly, and leads to tighter hexagonal packing. These structural changes synergistically enable the spatial delocalization in amino/ammonium clusters and effectively suppress non‐radiative transitions, thereby enhancing the quantum yield. Due to their aqueous processability and unique fluorescence, these polysiloxanes show promising potential for future applications.

In this research, a recyclable ordered necklace‐like “trimeric‐DDSQ”‐PDMS polysiloxane (DDDP) is presented. Specific bifunctional organosilicon building blocks, namely vinyl‐terminated double‐decker silsesquioxane (DDSQ‐Vi), hydrogen‐terminated double‐decker silsesquioxane (DDSQ‐H), and the dumbbell‐shaped precursor (DPD), are fabricated. Stepwise polymerization from DPD precursor enables the synthesis of ordered necklace‐like DDDPs. In this way, no additional purification or separation steps are necessary. DDDP contains a high proportion of nanocage‐shaped DDSQ within its organosilicon backbone. This structure endows DDDP with outstanding thermal stability, optical transparency, favorable mechanical characteristics, and recyclability. These properties highlight the potential of DDDP in applications such as electronic circuit packaging and material recycling.

Nonconventional fluorescent materials, which are nonaromatic or consist of isolated aromatic systems, have attracted extensive attention because of their aggregation‐induced emission properties. The mechanism of nonconventional fluorescence remains incompletely understood, hindering the prediction and modulation of its emission color. Achieving full‐color tunability in such systems, particularly within elastomers, is highly challenging. Herein, fluorescent cross‐linked polysiloxanes are synthesized using aliphatic amino‐terminated polysiloxane and glutaraldehyde, exhibiting full‐color emission that can be continuously tuned through thermal treatments within a single material system. Thermal treatment of cross‐linked polysiloxanes enables precise control over the structural evolution of fluorophores from imines to 3‐(2‐piperidyl)pyridinium derivatives and their aggregation states. It enables the continuous and wide‐range modulation of the emission color. Additionally, the intramolecular and intermolecular charge transfers of the novel unconventional fluorophore, 3‐(2‐piperidyl)pyridinium derivatives, have been identified, which are of great significance for aggregation‐induced bathochromic fluorescence. Prepared from all commercial chemicals, these cross‐linked polysiloxanes show great potential for large‐scale production and applications, especially as flexible fluorescent light‐conversion layers and solvent‐responsive smart materials. Furthermore, our research is expected to inspire the innovation of unconventional fluorophores in multiple dimensions.

Copper nanoparticle (Cu NP) is a promising replacement for noble metal nanoparticles due to its high electrical conductivity and low cost. However, Cu NPs are relatively active compared to noble metals, and current ways of protecting Cu NPs from oxidation by encapsulation have severe drawbacks, such as a long reaction time and complicated processes. Here, a facial and effective method to prepare the mesosphere of carbon-shelled copper nanoparticles (Cu@MC) was demonstrated, and the resulting Cu@MC was both highly electrically conductive and thermally stable. Cu@organic (100 nm) was first synthesized by the reduction of Cu ions with poly (vinyl pyrrolidone) (PVP) and sodium poly ((naphthalene-formaldehyde) sulfonate) (Na-PNFS) as soft templates. Then, the carbon shells were obtained by in situ carbonization of the polymer soft templates. The Cu@organic and Cu@MC showed an anti-oxidation ability up to 175 and 250 °C in the air atmosphere, respectively. Furthermore, the Cu@MC exhibited excellent volume resistivity of 7.2 × 10⁻³ Ω·cm under 20 MPa, and showed promising application potential in electric sensors and devices.

A polymer based bag filter with high temperature resistance plays a key role in dust and acid gas treatment in the power industry. Currently, the polymers used for preparing filters with improved heat resistance include those with a high content of aromatic units. But the aromatic structure inevitably leads to a high melting point, which is disadvantageous for melt spinning. Here, we report a polyamide 66 and polyamide 6T copolymer (PA66-co-PA6T) fiber with both high thermal stability and good spinnability. The retention rates of heat resistance of fibers after heat treatment at 185 °C and 200 °C were higher than 97.8% and 88.4%, respectively. This high thermal stability is ascribed to the high thermal degradation activation energy (E), which was confirmed by DSC, TG, and XRD characterization studies and fitting of kinetic data. PA66-co-PA6T with good melt spinnability, high heat resistance strength and low cost is expected to be applied in high-temperature resistance filtration equipment such as bag filters, expanding the application range of PA66 materials.

A new type of cyclo-linear structured high phenyl content siloxane elastomer (Ph-CLS-E) was prepared through a “one-pot” hydrosilylation reaction that takes advantage of the reactivity differences of cyclic and linear precursors and a vinyl-diphenylpolysiloxane crosslinker. The cyclo-linear structure is based on the hydrosilylation of 1,5-dimethyl-1,5-divinyl-3,3,7,7-tetraphenylcyclotetrasiloxane (ViPh-Cyclo) and an α,ω-bis(dimethylsiloxyl)polydiphenylsiloxane oligomer (H-Ph-Linear). The cyclo-linear precursor can further react with the α,ω-bis(methyldivinylsiloxyl)poly(methylvinylsiloxane-diphenylsiloxane) (Vi-ViPh-Crosslinker) to form the Ph-CLS-E elastomer, in which the molar ratio of Ph : Si > 1. Ph-CLS-Es are transparent elastomers with a high refractive index of ≥1.580 (@589 nm) and an excellent thermal stability of T_{d 5wt%} ≥ 437 °C. Meanwhile, the flexibility of Ph-CLS-E is improved with the increasing content of the cyclo-linear unit. The maximum elongation at break of Ph-CLS-E reaches ∼189%. This research indicates that the high phenyl content cyclo-linear structure inhibits the thermal decomposition of the siloxane chain even at low crosslinking density. It provides an effective way to fabricate siloxane elastomers with the combination of high RI, excellent flexibility and thermal stability, which shows application prospects in optoelectronic encapsulation and packaging.