Surface functionalization of MoS2 with POSS for enhancing thermal, flame-retardant and mechanical properties in PVA composites

Abstract

Surface functionalization of molybdenum disulfide (MoS₂) was prepared by a simple reflux reaction between DITG-MoS₂ and octa-vinyl polyhedral oligomeric silsesquioxanes (OvlPOSS). The structure of OvlPOSS-MoS₂ was confirmed by XRD, FTIR and TEM. The SEM and TEM results of fracture surface exhibited that OvlPOSS-MoS₂ was dispersed well in the matrix due to the good interfacial interaction between the functionalized MoS₂ and PVA. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results indicated that the thermal decomposition temperature and the glass transition temperature (T_g) were improved. Compared with pure PVA, the maximum degradation temperature of the PVA/OvlPOSS-MoS₂ nanocomposites was increased by 23 °C, and the T_g of the PVA/OvlPOSS-MoS₂ was improved by 10.2 °C. Meanwhile, the peak of heat release rate (pHRR) and total heat release (THR) were decreased. The tensile stress was increased by 57% with addition of 2 wt% OvlPOSS-MoS₂. Moreover, the addition of OvlPOSS-MoS₂ significantly decreased the gaseous products, including hydrocarbons, carbonyl compounds and carbon monoxide, which was attributed to the synergistic effect of OvlPOSS and MoS₂: the adsorption and barrier effect of MoS₂ inhibited the heat and gas release and promoted the formation of graphitized carbons, while OvlPOSS improved the thermal oxidative resistance of the char layer.