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

Polymers

Bing Guo¹  Siok Wei Tay²  Zhaolin Liu² 

[1] Department of Chemical & Biomolecular Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260, Singapore;Institute of Materials Research and Engineering, 3 Research Link, 117602, Singapore;

关键词: hollow polymer microspheres;    keeping moisture;    composite membrane;    PEM fuel cell;   

DOI  :  10.3390/polym4031499

来源: mdpi

【 摘 要 】

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 (–SO₃H) 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 –SO₃H borne shell played a more effective role than those with the –CO₂H borne shell in augmenting proton transport, in particular under low humidity or at medium temperatures. Single H₂-PEMFC test at 70 °C using dry H₂/O₂ further verified the impactful role of hydrophilic HPS in sustaining higher proton flux as compared to pristine Nafion membrane.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.