Reversible Self-Actuated Thermo-Responsive Pore Membrane

Abstract

Smart membranes, which can selectively control the transfer of light, air, humidity and temperature, are important to achieve indoor climate regulation. Even though reversible self-actuation of smart membranes is desirable in large-scale, reversible self-regulation remains challenging. Specifically, reversible 100% opening/closing of pore actuation showing accurate responsiveness, reproducibility and structural flexibility, including uniform structure assembly, is currently very difficult. Here, we report a reversible, thermo-responsive self-activated pore membrane that achieves opening and closing of pores. The reversible, self-actuated thermo-responsive pore membrane was fabricated with hybrid materials of poly (N-isopropylacrylamide), (PNIPAM) within polytetrafluoroethylene (PTFE) to form a multi-dimensional pore array. Using Multiphysics simulation of heat transfer and structural mechanics based on finite element analysis, we demonstrated that pore opening and closing dynamics can be self-activated at environmentally relevant temperatures. Temperature cycle characterizations of the pore structure revealed 100% opening ratio at T = 40 °C and 0% opening ratio at T = 20 °C. The flexibility of the membrane showed an accurate temperature-responsive function at a maximum bending angle of 45°. Addressing the importance of self-regulation, this reversible self-actuated thermo-responsive pore membrane will advance the development of future large-scale smart membranes needed for sustainable indoor climate control.

Artificial Perspiration Membrane by Programmed Deformation of Thermoresponsive Hydrogels

“…[13] Regulation of the evaporation rate is also important to prevent overcooling and wasting of sweat. [19] Here, we introduce an artificial perspiration membrane which automatically regulates evaporation rate at water-air Thermal management is essential for living organisms and electronic devices to survive and maintain their own functions. By contrast, it is possible to suppress evaporation on demand by blocking the evaporation area with valves like what peripheral muscles do for the perspiration.…”

Intelligent environmental nanomaterials

“…In literature, various existing membranes, organic and inorganic ones, have been utilized as matrix to fabricate intelligent gating membranes. The organic ones include polypropylene (PP), 95,96 polycarbonate (PC), 93,[97][98][99] polyethylene (PE), 90,91,100 polytetrafluoroethylene (PTFE), [101][102][103] Nylon-6, [104][105][106] polyvinylidene fluoride (PVDF), 87,92,104,[107][108][109][110] polyimide (PI), polyamide (PA), 80,81,112 poly(ethylene terephthalate) (PET), [113][114][115] polysulfone, 116 poly(viny1 chloride) (PVC), 117 polyethersulfone (PES), [118][119][120] while the inorganic membranes mainly include anodic aluminum oxide (AAO), 121,122 nanoporous silica, 123 and nanoporous silicon nitride membranes. 124 Although one-step formation of stimuli-responsive gating membranes by phase inversion method have also been reported in literature, it is applicable to only a small group of responsive polymers.…”

“…143 Ever since, there had been an explosive growth of using PNIPAM or PINPAM copolymers on different porous substrates for intelligent gating membranes. 90,91,95,97,101,107,115,[144][145][146][147] In addition, valuable efforts were made to increase (e.g., to 40 o C) and decrease (e.g., to 17 °C) the LCST by introducing hydrophilic or hydrophobic moieties into PNIPAM copolymers, respectively, 104 which offers more flexibility in applying intelligent gating membranes to environmental separations.…”

Processing and Thermal Response of Temperature-Sensitive-Gel(TSG)/Polymer Composites

“…Functional porous membranes/films, which can control the transfer of air, humidity, light, and temperature, are important and have attracted much attention due to their wide use in fields such as food packaging, electronics, the energy sector, and daily necessities [17,18,19,20,21,22,23,24,25,26,27,28]. Most of these porous membranes/films are environment- or signal-responsive.…”