Embedding of Hollow Polymer Microspheres with Hydrophilic Shell in Nafion Matrix as Proton and Water Micro-Reservoir

Abstract

Assimilating hydrophilic hollow polymer spheres (HPS) into Nafion matrix by a loading of 0.5 wt % led to a restructured hydrophilic channel, composed of the pendant sulfonic acid groups (-SO 3 H) and the imbedded hydrophilic hollow spheres. The tiny hydrophilic hollow chamber was critical to retaining moisture and facilitating proton transfer in the composite membranes. To obtain such a tiny cavity structure, the synthesis included selective generation of a hydrophilic polymer shell on silica microsphere template and the subsequent removal of the template by etching. The hydrophilic HPS (100-200 nm) possessed two different spherical shells, the styrenic network with pendant sulfonic acid groups and with methacrylic acid groups, respectively. By behaving as microreservoirs of water, the hydrophilic HPS promoted the Grotthus mechanism and, hence, enhanced proton transport efficiency through the inter-sphere path. In addition, the HPS with the -SO 3 H borne shell played a more effective role than those with the -CO 2 H borne shell in augmenting proton transport, in particular under low humidity or at medium temperatures. Single H 2 -PEMFC test at 70 °C using dry H 2 /O 2 further verified the impactful role of hydrophilic HPS in sustaining higher proton flux as compared to pristine Nafion membrane.

Gyroid structured aqua-sheets with sub-nanometer thickness enabling 3D fast proton relay conduction

“…The number of water molecules per sulfonate group in Film-Cub bi (15.6) is calculated to be about 5.6. Taking into account the general knowledge that one sulfonic acid group has the ability to strongly interact with up to 8–14 water molecules,60–62 it is plausible that the absorbed water molecules are placed exclusively on the gyroid minimal surface where the sulfonate/sulfonic-acid groups of Diene-GZI are aligned densely.…”

Nafion Composite Membranes Impregnated with Polydopamine and Poly(Sulfonated Dopamine) for High-Performance Proton Exchange Membranes

“…However, excessively high WU inevitably degrades the dimensional stability of membranes, resulting in a decrease in their mechanical properties and the overall performance of the resultant membrane–electrode assembly (MEA). Not only that, the WU and SR of a membrane are known to depend on the porosity of the membrane; high porosity leads to a high WU and SR. − …”

Improve the Performance of Mechanoelectrical Transduction of Ionic Polymer-Metal Composites Based on Ordered Nafion Nanofibres by Electrospinning

“…Morohoshi et al established methods to evaluate key properties such as water diffusion, gas permeability, and mechanical strength based on coarse-graining models, and an optimal design of the polymer structure could be established by the method [27]. Bing Guo et al synthesised a hydrophilic polymer shell on a silica microsphere template and the subsequent removal of the template by etching to obtain the tiny hydrophilic hollow chamber, because it is critical to retaining moisture and facilitating proton transfer in the composite mats [28].…”