1.D.88.  The Hydrogel-conducting Polymer Asymmetric Heterogeneous Membrane (HPAHM) Family 

Heterogeneous membranes composed of asymmetric structures or compositions have potential as sensors, molecular sieves, and energy devices due to their unique ion transport properties such as ionic current rectification and ion selectivity. Bao et al. 2017 studied a simple, versatile, low-cost approach to fabricate hydrogel/conducting polymer asymmetric heterogeneous membranes with electro-/pH-responsive 3D micro-nanoscale ion channels. Due to the asymmetric heterojunctions between positively charged nanoporous polypyrrole (PPy) and negatively charged microscale porous hydrogel poly (acrylamide-co-acrylic acid) (P(AAm-co-AA)), the membrane can rectify ion transmembrane transport in response to both electro- and pH-stimuli. The membranes are not dependent on elaborately fabricated 1D ion channel substrates and hence can be prepared in a low-cost and large-area fashon. The hybridization of hydrogel,  conducting polymers offers a novel strategy for constructing low-cost, large-area and multifunctional membranes, expanding the tunable ionic rectification properties into macroscopic membranes with micro-/nanoscale pores (Bao et al. 2017).