Fractionation of nanoparticles with different sizes from the mixture by using a single membrane would reduce the membrane cost and enhance the efficiency. In this study, an amphiphilic pH-responsive copolymer was prepared by grafting a pHresponsive hydrophilic polymethacrylic acid (PMAA) side chain from a hydrophobic poly(vinylidene fluoride-co-chlorotrifluoroethylene), P(VDF-CTFE) backbone. Subsequently, the isoporous pH-responsive membranes (PPMs) were prepared from the functional copolymers with different PMAA chain lengths. PPM indicated reversible pore size decreasing with the increasing pH of the feed. Moreover, the membrane pore size variation range was further extended by adjusting the PMAA side chain length of the copolymer to reach a wide range from 10.2 to 34.5 nm. Owning to the amphiphilic nature of the copolymer, PPM showed a narrow pore size distribution which is responsible for the much higher pure water flux of PPM than the conventional UF membrane with similar retention capability. In the fractionation test, the mixed 20 and 30 nm polystyrene nanoparticles were penetrating PPM at pH 11 and 3, respectively. The pH-responsive PPM indicated great potential for nanoparticle fractionation, while the uniform pores of PPM further enhanced the membrane performance in terms of permeability and selectivity.

Claiming water from the atmosphere or fog harvesting could be a promising route to relieve the scarcity of fresh water. The unidirectional water transportation of a Janus membrane has indicated a potential way of efficient fog collection. In this study, a facile two-step electrospun protocol was established to patch hydrophobic PVDF domains on a hydrophilic PAN nanofibrous texture in a designer manner inspired by the heterogeneous back structure of a desert beetle. The tuned heterogeneous surface morphology and the vertically varied wettabilities of the prepared Janus membrane indicated a more significant fog collection rate (FCR) than the homogeneous PAN or PVDF membrane. Moreover, the optimized Janus membrane (10 min of PVDF spinning on PAN to reach a coverage of 44.3%) indicated a promising FCR at 88.5 mg/(min cm2), which was comparable with the highest reported FCR of a more complicated organic/inorganic Janus system. It is possible that the synergistic effect of the capillary force and the Laplace pressure determined the high FCR of the Janus membrane in this study. In addition, the prepared Janus membrane was used for an efficient oil–water phase separation contributed by the excellent unidirectional water transportation effect. The novel morphology design protocol provided new insights of the Janus membrane fabrication, which obviously evoked the potential of the Janus membrane for practical applications.

Inspired by the stomatal of plant leaves, a photo-responsive membrane was developed to enhance the removal of irreversible membrane fouling and control molecule release. The photo-responsive polymers were prepared by...

No abstract

No abstract