Effect of Grafting Density on Molecular Bottlebrush Crystallization Behavior

Tethered polymer chains, or polymer brushes, have widely been studied for their novel physical behavior and for their myriad of applications.  In this presentation, we utilize a bottlebrush as a model system to study chain crystallization under confinement.  A series of bottlebrush samples composed of a Poly(2-hydroxyethyl methacrylate) backbone with poly(ethylene oxide) (PEO) side chains was fabricated at different grafting densities.  Both isothermal and non-isothermal crystallization studies were conducted to reveal the side chain grafting density effect on the sidechain packing and overall structure of the bottlebrush.  Additionally, the retention of chain orientation within the melt state at elevated temperature was examined through a thermal fractionalization method and grafting density-dependent memory effects were discovered. This work suggests an architecture-based dependence on the nucleation and crystallization behavior in molecular bottlebrushes.