Control-synthesized multilayer hyperbranched–hyperbranched polyethers with a tunable molecular weight and an invariant degree of branching

Abstract

A strategy to synthesize multilayer hyperbranched–hyperbranched macromolecules with an invariant degree of branching (DB) and a controllable molecular weight (MW) is realized by taking advantages of competing reactions. The invariant DB and tunable MW lead to hyperbranched molecules with controlled sub-nano to nano pores, which have potential applications in supramolecular capsulation, gas storage, separation, and catalysis. Hyperbranched molecules with a low MW are obtained in a one-pot reaction due to the competing reactions between AB₂ monomers. For our systems, hyperbranched molecules with much higher yet controlled MW can be achieved by adding additional batches of the same AB₂ monomers. When different AB₂ monomers with different spacer lengths are fed alternatively, multilayer core–shell hyperbranched macromolecules with a controlled layer thickness or MW are obtained. More importantly, the multilayer hyperbranched–hyperbranched macromolecules show not only tunable MW but also invariant DB. In addition, it is found that the T_g of core–shell hyperbranched molecules is mainly determined by the outermost layer.