Thermally stable hyperbranched nonlinear optical polyimides using an “A2+B3” approach

► A series of hyperbranched NLO polyimides were synthesized from “A2+B3” approach. ► The presence of the imide rings imparted excellent thermal stability. ► Site isolation effects provided enhanced NLO properties. ► These hyperbranched polymers exhibited excellent temporal stability at 120 °C.