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We fabricate composite hydrogels using surface‐modified cellulose nanofiber (CNF) and N‐isopropylacrylamide (NIPAm) as a multifunctional crosslinker and monomer, respectively. We expect to produce unique network structures that lead to elastomeric properties rarely reported for CNF‐based materials. The modification of CNF is performed to introduce polymerizable vinyl groups onto the surface of CNF via condensation between the surface hydroxyl groups and 3‐(trimethoxysilyl)propylmethacrylate. The modification and morphology of the surface‐modified CNF (mCNF) are confirmed by FTIR, solid‐state NMR, and FE‐SEM, respectively. We conduct in situ radical polymerization under various conditions using mixtures of the mCNF aqueous suspension, NIPAm monomer, radical initiator, and catalyst. The mechanical properties of the obtained hydrogels (water content = 90 wt %) are evaluated. The gels can be elastically stretched to more than 700 times their original lengths and exhibit an apparent shape recovery with a small permanent deformation (∼1/5 of the applied deformation under the gravity field). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42906.

The partial molal volumes, \barV°, of [M(phen)3]Cl2 (M=Fe(II), Co(II), Ni(II), Cu(II), and Zn(II)) and 1,10-phenanthroline were determined from density measurements at 25 °C. From the values for \barV° of [M(phen)3]2+, M2+ and phen the volume changes for complex formation of [M(phen)3]2+, Δ\barV°, were caluculated. Values for \barV° of [M(phen)3]Cl2 varied from 445.1 cm3 mol−1 for [Fe(phen)3]Cl2 to 458.1 cm3 mol−1 for [Zn(phen)3]Cl2 and were in the order, [Fe(phen)3]2+<[Co(phen)3]2+>[Ni(phen)3]2+<[Cu(phen)3]2+<[Zn(phen)3]2+. The Δ\barV° of [Fe(phen)3]2+ was significantly small, 4.7 cm3 mol−1. While those of other metal chelate ions were similar values, ca. 20 cm3 mol−1. The smaller Δ\barV° of [Fe(phen)3]2+ is considered to be due to the spin change from the high-spin aqua ion, [Fe(OH2)6]2+, to the low-spin complex ion, [Fe(phen)3]2+.

For the conversion from quinquedentate complexes, [Co(edtaH)(H2O)] and [Co(edta)(H2O)]−, into the sexidentate complex, [Co(edta)]−, the respective volume changes were measured from the density data at 25 °C. The volume change was determined as well for the proton dissociation of [Cr(edtaH)(H2O)]. A comparison of the volume changes in the Co(III) system with the corresponding Cr(III) system supports the recent view that edta forms a sexidentate complex with Cr(III) in the pH 3.5—6.5 range.

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