Nanoscale Velcro-like Effect: Synthesis and Rheological Properties of Polymer Loop-Grafted Nanoparticles

Grafted chain architectures are used to control the interfacial chain entanglements and reinforcement in polymer nanocomposites. This study aims to create complex grafted chain topologies to alter free matrix chain relaxations and viscoelastic properties. Polymer loop-grafted particles were synthesized, and rheological behavior of their composites were explored. First, linear poly(methyl methacrylate) chains were grafted on 15 nm SiO₂ nanoparticles by RAFT polymerization. After chain end modification with thiol group, loops between PMMA grafts were achieved by thiol-ene click reaction. Molecular weights of connected chains were determined using gel permeation chromatography after etching the nanoparticles. The dispersion of loop grafted chain nanoparticles was then examined in transmission electron microscopy. The linear viscoelasticity of polymer loop-grafted nanoparticle composites and their comparison to that of bare and linear polymer-grafted composites at same particle loading will be discussed.