Membranes with porous substrates and functional gates that are responsive to environmental stimuli are attracting increasing interest from various fields. Their permeation properties can be controlled or adjusted by the gates according to the external chemical and/or physical environment, and they may find various applications e.g. in controlled drug delivery, bioseparation, chemical separation, water treatment, tissue engineering, and as chemical sensors. The functional gates for stimuli-responsive membranes serve as chemical valves, and have been reported to act in response to changes in environmental temperature, [1-5] pH, [5-10] ionic strength, [11] glucose concentration, [12, 13] electric field, [14] light, [15] redox properties, [16] or different molecules. [17-19] There are many cases in which environmental temperature fluctuations occur naturally, and in which the temperature stimuli can be easily designed and artificially controlled; therefore much attention has recently been focused on thermoresponsive membranes. [2-1] Up to now, almost all of the thermoresponsive gating membranes have featured positively thermoresponsive characteristics, that is, the membrane permeability increases with increasing environmental temperature, because all of the thermoresponsive functional gates were constructed from poly (Nisopropylacrylamide) (PNIPAM). [1-5] In these cases, the membrane pores change from a "closed" to an "open" state when the environmental temperature increases from below the lower critical solution temperature (LCST) of PNIPAM to above the LCST, as a result of the swelling/shrinking conformational change of the polymer. In certain applications, however, an inverse mode of the thermoresponsive gating behavior of the membranes is preferred. Here we report a novel family of thermoresponsive gating membranes with negatively thermoresponsive gating characteristics, that is, "opening" of the membrane pores is induced by a decrease rather than an increase in temperature.