pH-responsive functionalized surface active ionic liquid as an enhanced medium for efficient extraction and in-situ separation of flavonoids in Vitex negundo L. Leaves

•pH-responsive behavior of functionalized surface active ionic liquid (SAIL) has been explored.•Functionalized SAIL had higher extraction yield for flavonoids.•Simple pH adjustment can realize in-situ separation of target components.•Functionalized SAIL can be recycled.•Molecular simulation reveals the extraction mechanism.