Polyhedral Oligomeric Silsesquioxane Induced Thermomechanical Reinforcement in Polymer Films Using Only Parts-per-Million Content

Reinforcement of polymers by nanoparticles has been a challenge due to aggregation and solubility limits, especially at high loads. In this research, a robust and environmentally friendly fabrication approach to produce films reinforced with only parts-per-million (ppm) octamethyl-polyhedral oligomeric silsesquioxane (mePOSS) using conventional extrusion and blow molding processing is demonstrated. The nanocomposites exhibit enhanced thermomechanical properties, and only 160 ppm mePOSS increase the tensile mechanical modulus,E, by approximate to 120% relative to the neat polymer. Remarkably, there is no penalty on strain at fracture epsilon(f), as usually seen in reinforced (nano) composites. Toughness, yield stress, tear, and puncture resistance are also an increasing function of mePOSS content. Furthermore, mePOSS also increase the thermal decomposition temperature and melting temperature. The placement of mePOSS in the molecular web is key to the thermal and mechanical reinforcement and these properties maximize when the nanoparticle size < D > matches the tube diameterd(t), i.e., < D >/d(t) approximate to 1. This simple fabrication approach combined with ppm POSS content and tunability of physical properties afforded by the location of POSS in the entangled web offers a new paradigm for the bottom-up design of tunable lightweight polymer nanocomposites with superior thermomechanical and transport properties.