In situ polymerization and polymer grafting to stabilize polymer-functionalized nanoparticles in polymer matrices

摘要

Control of nanoparticle dispersion within a polymer matrix is a critical consideration when designing solid state hybrid polymer/inorganic nanoparticle materials. Polymer-functionalized nanoparticles are effective hybrid components for increasing particle miscibility in polymer matrices. Entropic and enthalpic contributions to the dispersion state of polymer-functionalized nanoparticles are well-understood and have been used extensively to enhance nanoparticle miscibility in polymer matrices. However, systems of immiscible graft and matrix chains remain understudied, in part due to the challenges associated with mixing unlike components. Here, a new method for stabilizing polymer-functionalized nanoparticles in an immiscible matrix is reported. Poly(cyclooctadiene) (PCOD) functionalized nanoparticles are dispersed within poly (styrene) and poly(methyl methacrylate) matrices by an in situ polymerization and polymer grafting process in which polymer-grafted nanoparticles are initially well-solubilized in a monomer solution prior to monomer polymerization. The in situ polymerization arrests particle mobility as the matrix increases in chain length, and thermodynamic penalties to mixing are reduced by the in situ grafting of matrix chains from the PCOD segments on the nanoparticle surfaces. This method adapts commercially relevant free-radical polymerization processes for the development of well-dispersed hybrid polymer/inorganic nanoparticle materials. The reported method is a potential avenue to improve particle dispersion needed for solid state material reinforcement without relying on miscible particle and polymer components.