Synthesis and Characterization of a Novel Heteropoly Acid/Hydrogel Composite Junjie Zhu, Takehiko Gotoh, Satoshi Nakai and Masahiro Sadakane MATEC Web Conf., 333 (2021) 11005 Published online: 08 January 2021 DOI: 10.1051/matecconf/202133311005