{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T11:18:53Z","timestamp":1788261533937,"version":"build-2803163510"},"reference-count":34,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T00:00:00Z","timestamp":1788220800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100015604","name":"Shanghai Polytechnic University","doi-asserted-by":"publisher","award":["XXKZD1601"],"award-info":[{"award-number":["XXKZD1601"]}],"id":[{"id":"10.13039\/501100015604","id-type":"DOI","asserted-by":"publisher"}]},{"award":["XXKZD1601"],"award-info":[{"award-number":["XXKZD1601"]}],"id":[{"id":"https:\/\/ror.org\/02as5yg64","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Gaoyuan Discipline of Shanghai-Materials Science and Engineering","award":["A30NH221903"],"award-info":[{"award-number":["A30NH221903"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Gels"],"abstract":"<jats:p>Poly(vinyl alcohol) (PVA)\/sodium alginate (SA) dual-network hydrogels were prepared via the freeze\u2013thaw method. Tensile testing, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and fiber-optic spectroscopy were employed for material characterization, and multiple metal ions were screened to optimize mechanical properties and ionic conductivity. The results showed that, at PVA:SA mass ratio of 2:1, the hydrogel achieved 163% elongation and 0.18 MPa tensile strength. Ca2+ crosslinking formed an enhanced structure with mechanical properties of 170% elongation and 0.21 MPa strength, and ionic conductivity (0.69 S\/m). Combined with colloidal photonic crystal (PC) templates, the PVA\/SA-PC film exhibited an inverted opal structure, showing sensitive color response (green to red) and diffraction red-shift toward Ca2+. The conductive film could power a small bulb, demonstrating potential for portable visual sensing applications.<\/jats:p>","DOI":"10.3390\/gels12090790","type":"journal-article","created":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T10:32:18Z","timestamp":1788258738000},"page":"790","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Dual-Network Poly(vinyl alcohol)\/Sodium Alginate Hydrogel Photonic Crystals Films for Visual Sensing"],"prefix":"10.3390","volume":"12","author":[{"given":"Shaoqian","family":"Zhang","sequence":"first","affiliation":[{"name":"School of Energy and Materials, Shanghai Thermophysical Properties Big Data Professional Technical Service Platform, Shanghai Engineering Research Center of Advanced Thermal Functional Materials, Shanghai Key Laboratory of Engineering Materials Application and Evaluation, Shanghai Polytechnic University, Shanghai 201209, 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China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuting","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Energy and Materials, Shanghai Thermophysical Properties Big Data Professional Technical Service Platform, Shanghai Engineering Research Center of Advanced Thermal Functional Materials, Shanghai Key Laboratory of Engineering Materials Application and Evaluation, Shanghai Polytechnic University, Shanghai 201209, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yunyan","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Energy and Materials, Shanghai Thermophysical Properties Big Data Professional Technical Service Platform, Shanghai Engineering Research Center of Advanced Thermal Functional Materials, Shanghai Key Laboratory of Engineering Materials Application and Evaluation, Shanghai Polytechnic University, Shanghai 201209, 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China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shuwen","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Energy and Materials, Shanghai Thermophysical Properties Big Data Professional Technical Service Platform, Shanghai Engineering Research Center of Advanced Thermal Functional Materials, Shanghai Key Laboratory of Engineering Materials Application and Evaluation, Shanghai Polytechnic University, Shanghai 201209, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lishi","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Resources and Environmental Engineering, Shanghai Polytechnic University, Shanghai 201209, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9813-532X","authenticated-orcid":false,"given":"Cheng","family":"Chen","sequence":"additional","affiliation":[{"name":"School of Energy and Materials, Shanghai Thermophysical Properties 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