Yamamoto Yoshimasa, Kawahara Seiichi
Department of Chemical Science and Engineering, National Institute of Technology, Tokyo College, 1220-2 Kunugida, Hachioji, Tokyo 193-0997, Japan.
Department of Materials Science and Bioengineering, Nagaoka University of Technology, 1603-1, Kamitomioka-cho, Nagaoka, Niigata 940-2188, Japan.
ACS Omega. 2025 Apr 23;10(17):17576-17583. doi: 10.1021/acsomega.4c11363. eCollection 2025 May 6.
Rubbery soft polymer electrolyte membranes (PEMs) prepared from naturally occurring products are in high demand for the fabrication of flexible fuel cells as a multipurpose energy source to achieve a carbon-neutral society. This work describes the preparation of a rubbery soft PEM from deproteinized natural rubber (DPNR) by grafting-copolymerizing ethyl -styrenesulfonate (SSEt) onto the surface of rubber particles in the latex stage, followed by hydrolysis with NaOH and cast film formation to construct a nanomatrix channel. The resulting rubbery soft PEM, a graft copolymer of DPNR and poly(-styrenesulfonic acid) (DPNR--PSS), is characterized by H NMR spectroscopy, transmission electron microscopy (TEM), impedance analysis, and tensile testing. The hydrophobic rubber particles with a diameter of about 1 μm are well dispersed in the continuous nanochannel of hydrophilic poly(-styrenesulfonic acid) with a thickness of about 10 nm that possesses a high proton conductivity, owing to an efficient proton transportation, which is beneficial for polymer electrolyte fuel cells. σ* is the proton conductivity per unit equivalent of sulfonic acid, which is distinguished from the proton conductivity, σ. The value of σ* for the DPNR--PSS prepared with 1.0 mol/kg-rubber of SSEt is 2.6 (S/cm)/meq, which is approximately 1.4 times higher than that of the perfluorosulfonic acid membrane Nafion117, whereas its σ is lower. The apparent activation energy of DPNR--PSS (3.2 kJ/mol) is lower than that of Nafion117, and its stress at break (6.9 MPa) is higher than that of DPNR. The high σ*, low apparent activation energy, and outstanding tensile strength of DPNR--PSS can be attributed to the formation of the nanomatrix channel.
由天然产物制备的橡胶状软质聚合物电解质膜（PEMs）在制造柔性燃料电池方面有很高的需求，柔性燃料电池作为一种多用途能源，有助于实现碳中和社会。本工作描述了一种橡胶状软质PEM的制备方法，该方法是在胶乳阶段将乙基苯乙烯磺酸盐（SSEt）接枝共聚到脱蛋白天然橡胶（DPNR）颗粒表面，然后用NaOH水解并流延成膜以构建纳米基质通道。所得的橡胶状软质PEM，即DPNR与聚（苯乙烯磺酸）的接枝共聚物（DPNR-PSS），通过核磁共振氢谱、透射电子显微镜（TEM）、阻抗分析和拉伸试验进行表征。直径约为1μm的疏水性橡胶颗粒很好地分散在厚度约为10nm的亲水性聚（苯乙烯磺酸）连续纳米通道中；由于高效的质子传输，该纳米通道具有高质子传导率，这对聚合物电解质燃料电池是有利的。σ是每单位磺酸当量的质子传导率，与质子传导率σ不同。用1.0mol/kg橡胶的SSEt制备的DPNR-PSS的σ值为2.6（S/cm）/meq，约为全氟磺酸膜Nafion117的1.4倍，而其σ较低。DPNR-PSS的表观活化能（3.2kJ/mol）低于Nafion117，其断裂应力（6.9MPa）高于DPNR。DPNR-PSS的高σ*、低表观活化能和出色的拉伸强度可归因于纳米基质通道的形成。
