The thermomechanical properties of polymer nanocomposites are critically dependent upon the dispersion of nanoparticles (NPs) in the matrix as well as the nature of the nanoparticle−polymer interface. One strategy to control the interface is to covalently attach a polymer with the same or similar chemistry as that of the matrix onto the surface of NPs. Polyolefin composites suffer from the lack of good dispersion of NPs in the matrix. They are conventionally prepared by extreme extrusion mixing of inorganic particles and the polymer in the melt which in most cases leads to large aggregates, significantly decreasing reinforcement. While controlled radical polymerization methods do not allow the polymerization of polyolefins such as polyethylene, a substitute strategy is controllably attaching polyolefin-like polymers onto the NP surface. In this work, the surface-initiated RAFT polymerization was used to anchor poly(hexyl, lauryl, and stearyl methacrylates) on silica nanoparticles (Figure 1). The long alkyl side-chains can create an olefin-like interface and improve the compatibility of modified particles with polyolefins. Subsequently, we investigated the dispersion of these poly(alkyl methacrylates)-modified silica NPs in polyolefins such as linear low density polyethylene (LLDPE). The TEM results (Figure 2) of the poly(stearyl methacrylate)-grafted silica (PSMA-g-SiO2) showed a dispersed state throughout the LLDPE matrix. The nanocomposite filled with PSMA-g-SiO2 also showed improved mechanical and gas barrier properties.

Poly(alkyl methacrylates)-grafted silica nanoparticles in linear low-density polyethylene nanocomposites

251st National Meeting (2016)

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