Topological Effects of Dendronized Polymers on Their Thermoresponsiveness and Microconfinement
Gang Xu, Jiaxing Zhang, Ruitong Jia, Wen Li, Afang Zhang
Abstract
Topological structures can provide dendritic polymers with featured properties through cooperative effects beyond their molecular structures. Herein, we report the synthesis of a series of oligoethylene glycol (OEG)-based dendronized polymers, which carry the first generation of 2-fold, 4-fold, or 6-fold dendritic OEG pendants with methoxyl or ethoxyl terminals. Depending on the OEG branching density, these polymers show different molecular thicknesses and exhibit characteristic thermoresponsiveness with phase transition temperatures in the range of 16.6–67.2 °C. Furthermore, the higher the OEG branching density, the higher the shielding to the interior parts from the dendritic OEGs cooperatively to exhibit “molecular envelope” effects. This molecular microconfinement formed from the crowded OEG dendrons was further investigated through covalently linked or physically mixed dye. Topological structures of the polymers are discovered to play a key role in encapsulation of the dye guest and can modulate its transition within the aggregates through the thermally induced phase transitions.