As a graphene-like layered nano-material, molybdenum disulfide (MoS 2 ) has gained much attention from the materials fields. In our research, MoS 2 /poly(vinyl alcohol) (PVA) nanocomposites are prepared by solvent blending method. The morphology, thermal properties, fire resistance properties and mechanical properties of the PVA/MoS 2 nanocomposites are studied. MoS 2 is homogeneously dispersed and partially exfoliated in the PVA matrix as indicated by X-ray diffraction (XRD) pattern, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) characterization. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results indicate improved the thermal decomposition temperature and the glass transition temperature (T g ). The thermal degradation temperature is increased by 20-40 uC. Meanwhile, the peak of heat release rate (pHRR) and total heat release (THR) are decreased by 33% and 20%, respectively. Storage modulus at 40 uC is increased by 28%, and the tensile strength is increased by 24% upon addition of 1 wt% and 5 wt% MoS 2 . The improvements in the thermal properties, fire resistance properties and mechanical properties of PVA nanocomposites are attributed to the good dispersion of MoS 2 , physical barrier effects of MoS 2 and strong interactions between PVA and MoS 2 .

A series of flame retardant polylactide composites (FR-PLA) based on aluminum hypophosphite (AHP) were facilely prepared by melt blending method. The thermal behavior, flammability, and mechanical properties of FR-PLA composites were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), the UL-94 vertical burning test, limiting oxygen index (LOI), cone calorimeter testing, microscale combustion calorimetry, mechanical testing, and dynamic mechanical analysis (DMA). TGA results showed that the FR-PLA composites presented higher char residue and reduced mass loss rate than neat PLA. The FR-PLA composite showed excellent fire resistance, from no rating of neat PLA to a V0 rating of FR-PLA containing 20 wt % aluminum hypophosphite in the UL-94 test. The microscale combustion calorimetry test showed that the heat release capacity, the peak of heat release and the total heat release of FR-PLA composites were significantly decreased with the increase of AHP content. The cone calorimeter test also confirmed that the addition of AHP resulted in a significant decrease in the peak heat release rate value of PLA/AHP composites compared with pure PLA. Additionally, the results from DSC and DMA tests indicated that the addition of AHP into polylactide significantly changed the crystallization behavior and storage modulus of polylactide. However, the addition of AHP decreases the tensile strength and elongation at break. The char after LOI testing was investigated by scanning electron microscopy and craterlike morphology was observed on the surface of the char. The thermal degradation process of FR-PLA composites was analyzed by real-time Fourier transform infrared spectroscopy.

Nanotechnology-based pesticide formulations can improve the utilization rate of pesticides and reduce their negative effects on the environment. In this work, prochloraz was encapsulated within the pores of mesoporous silica nanoparticles (MSNs) attached covalently chitosan on the surface as gatekeepers via a silane coupling agent to prepare MSNs-chitosan@prochloraz nanoparticles. The results demonstrated that the obtained nanoparticles had a relatively high loading efficiency of prochloraz (25.4% w/w) and enhanced the light stability of prochloraz effectively. The nanoparticles showed excellent esterase and pH dual-responsive properties with controlled release behavior. The biological activity survey confirmed that the acid and enzyme produced by infected fruit can easily open the "gate" guarded by chitosan to achieve esterase and pH triggered on-demand pesticide release. Compared with prochloraz emulsifiable concentrate, preharvest application of MSNs-chitosan@prochloraz nanoparticles possessed a longer duration and a better antifungal activity against citrus diseases. The toxicity of the nanoparticles to zebrafish was reduced more than 6-fold compared with that of prochloraz technical. These results demonstrated that the MSNschitosan@prochloraz nanoparticles had potential as an environmentally friendly preharvest treatment agent in agricultural application.

Hierarchical mesoporous silica@Co–Al layered double hydroxide (m-SiO2@Co–Al LDH) spheres were prepared through a layer-by-layer assembly process, in order to integrate their excellent physical and chemical functionalities. TEM results depicted that, due to the electrostatic potential difference between m-SiO2 and Co–Al LDH, the synthetic m-SiO2@Co–Al LDH hybrids exhibited that m-SiO2 spheres were packaged by the Co–Al LDH nanosheets. Subsequently, the m-SiO2@Co–Al LDH spheres were incorporated into epoxy resin (EP) to prepare specimens for investigation of their flame-retardant performance. Cone results indicated that m-SiO2@Co–Al LDH incorporated obviously improved fire retardant of EP. A plausible mechanism of fire retardant was hypothesized based on the analyses of thermal conductivity, char residues, and pyrolysis fragments. Labyrinth effect of m-SiO2 and formation of graphitized carbon char catalyzed by Co–Al LDH play pivotal roles in the flame retardance enhancement.

Microcapsules are highly desirable for attaining the most effective utilization of the pesticide as well as reducing environmental pollution. In this work, a novel urease-responsive system was prepared using isocyanate-functionalized silica cross-linked with polyethylenimine (silica–IPTS–PEI) via urea bonds. The results demonstrated that the silica–IPTS–PEI microcapsules had a high pendimethalin loading efficiency (approximately 30% w/w) and could effectively enhance the thermal and light stability of pendimethalin. The release curves agreed with the Ritger and Peppas equation, and the release of pendimethalin was diffusion-controlled. The release rates of synthesized silica-IPTS-PEI microcapsules showed positive correlation with the temperature. In weak acid and base conditions, the pendimethalin release rates were higher than under neutral conditions, and the silica–IPTS–PEI microcapsules displayed excellent urease-responsive property with controlled release performance. Compared with pendimethalin emulsifiable concentration, the silica-IPTS-PEI microcapsules had a longer duration and higher herbicidal activity against weeds in a greenhouse experiment. Allium cepa chromosome aberration assays showed that the microcapsules had lower genotoxicity than pendimethalin technical. Thus, the urease-responsive silica–IPTS–PEI microcapsules have a great potential application as an environmentally friendly herbicide formulation.