Preparation of polymer electrolyte membranes with continuous PEG channel via the fusion of self-assembled polycyclooctene-graft-polyethylene glycol copolymer micelles

Rational ion transport management mediated through membrane structures

Unique membrane structures endow membranes with controlled ion transport properties in both biological and artificial systems, and they have shown broad application prospects from industrial production to biological interfaces. Herein, current advances in nanochannel-structured membranes for manipulating ion transport are reviewed from the perspective of membrane structures. First, the controllability of ion transport through ion selectivity, ion gating, ion rectification, and ion storage is introduced. Second, nanochannel-structured membranes are highlighted according to the nanochannel dimensions, including single-dimensional nanochannels (i.e., 1D, 2D, and 3D) functioning by the controllable geometrical parameters of 1D nanochannels, the adjustable interlayer spacing of 2D nanochannels, and the interconnected ion diffusion pathways of 3D nanochannels, and mixed-dimensional nanochannels (i.e., 1D/1D, 1D/2D, 1D/3D, 2D/2D, 2D/3D, and 3D/3D) tuned through asymmetric factors (e.g., components, geometric parameters, and interface properties). Then, ultrathin membranes with short ion transport distances and sandwich-like membranes with more delicate nanochannels and combination structures are reviewed, and stimulus-responsive nanochannels are discussed. Construction methods for nanochannel-structured membranes are briefly introduced, and a variety of applications of these membranes are summarized. Finally, future perspectives to developing nanochannel-structured membranes with unique structures (e.g., combinations of external macro/micro/nanostructures and the internal nanochannel arrangement) for mediating ion transport are presented.

Stabilizing Liquid Electrolytes in a Porous PVDF Matrix Incorporated with Star Polymers with Linear PEG Arms and CycloPEG Cores

Porous membranes fabricated from poly(vinylidene fluoride) (PVDF) and a star polymer with linear poly(ethylene glycol) (PEG) arms and cycloPEG cores were fabricated via the phase-separation method. The porous gel polymer electrolytes (PGPEs) were obtained by immersing the porous membranes in the electrolyte solution. When the additive amount of star polymer was up to 20 wt %, the prepared membrane had the largest porosity and the pores were uniformly distributed in the membrane. The star polymer can not only decrease the crystallization of PVDF and enhance the absorption of liquid electrolyte but also offer ion conduction channels (cycloPEG cores). Therefore, the PGPE with 20 wt % star polymers exhibited competitive ionic conductivities of 1.27 mS cm^-1 at 30 °C and 2.89 mS cm^-1 at 80 °C. To stabilize the liquid electrolyte in the holes of porous membranes, a gelator was introduced in the liquid electrolyte to form gelled porous gel polymer electrolytes (GPGPEs), and the leakage of liquid electrolytes was thus remarkably reduced. The ionic conductivity of GPGPEs with 20 wt % star polymer and 1.5 wt % gelator was importantly improved at high temperatures (6.02 mS cm^-1 at 80 °C). We systematically investigated the electrochemical performances of PGPEs without star polymer, PGPEs with star polymer, and GPGPEs with star polymer. The incorporation of star polymers with linear PEG arms and cycloPEG cores into the PGPEs and GPGPEs significantly improved the electrochemical performances of the lithium metal/LiFePO₄ cell assembled with the PGPEs or GPGPEs.

Highly flexible reduced graphene oxide@polypyrrole-polyethylene glycol foam for supercapacitors

A flexible and free-standing 3D reduced graphene oxide@polypyrrole–polyethylene glycol (RGO@PPy–PEG) foam was developed for wearable supercapacitors. The device was fabricated sequentially, beginning with the electrodeposition of PPy in the presence of a PEG–borate on a sacrificial Ni foam template, followed by a subsequent GO wrapping and chemical reduction process. The 3D RGO@PPy–PEG foam electrode showed excellent electrochemical properties with a large specific capacitance of 415 F g⁻¹ and excellent long-term stability (96% capacitance retention after 8000 charge–discharge cycles) in a three electrode configuration. An assembled (two-electrode configuration) symmetric supercapacitor using RGO@PPy–PEG electrodes exhibited a remarkable specific capacitance of 1019 mF cm⁻² at 2 mV s⁻¹ and 95% capacitance retention over 4000 cycles. The device exhibits extraordinary mechanical flexibility and showed negligable capacitance loss during or after 1000 bending cycles, highlighting its great potential in wearable energy devices.

A flexible and free-standing 3D reduced graphene oxide@polypyrrole–polyethylene glycol (RGO@PPy–PEG) foam was developed for wearable supercapacitors.

Preparation of porous antibacterial polyamide 6 (PA6) membrane with zinc oxide (ZnO) nanoparticles selectively localized at the pore walls via reactive extrusion

Antibacterial polymer membranes have been widely used in many fields of our daily life. In this study, porous PA6 membrane with ZnO nanoparticles attaching on to the surface of inner pore walls is prepared. Firstly, SMA (styrene maleic anhydride copolymer) is used to graft onto the surface of ZnO nanoparticle in DMF (dimethylformamide). Then the pre-treated ZnO nanoparticles (ZnO-SMA) are added into SEBS (Styrene-ethylene-butylene-styrene copolymer)/PA6 (60/40 wt/wt) blends with co-continuous morphology. The effects of SMA molecular structure (molecular weight and maleic anhydride content) used for ZnO-SMA nanoparticles on their dispersion states in SEBS/PA6/ZnO-SMA nanocomposites are investigated. When SMA3 (MAH = 8 wt%, Mn = 250,000 g mol^-1), which has relatively higher molecular weight and lower MAH content, is used as the pre-treating agent, ZnO-SMA3 nanoparticles tend to be dispersed at the phase interface in SEBS/PA6/ZnO-SMA nanocomposites. However, when SMA2 (MAH = 23 wt%, Mn = 110,000 g mol^-1) with relatively lower molecular weight and higher MAH content is used, no ZnO-SMA2 nanoparticles locate at the interface but stay within PA6 phase. Porous PA6 membranes are obtained by selectively etching SEBS phase out with xylene. It can be found that porous PA6 membrane containing ZnO-SMA3 nanoparticles still exhibits much better antibacterial property (R = 3.76) toward S. aureus even at a very low ZnO content (0.5 wt%). This result should be ascribed to almost all the ZnO-SMA3 nanoparticles being exposed to the surface of inner pore walls of PA6 membrane. This work proposes an effective method to prepare porous polymer membrane with functional nanoparticles selectively located at the inner pore walls.