Nagai Daisuke, Isobe Naoki, Inoue Tatsushi, Okamoto Shusuke, Maki Yasuyuki, Yamanobe Takeshi
School of Food and Nutritional Science, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Shizuoka, Japan.
Division of Molecular Science, Faculty of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu 376-8515, Gunma, Japan.
Gels. 2022 Jul 11;8(7):435. doi: 10.3390/gels8070435.
We investigated the gelation of a hydrophilic polymer with metal-coordination units (HPMC) and metal ions (Pd or Au). Gelation proceeded by addition of an HPMC solution in -methyl-2-pyrrolidone (NMP) to a metal ion aqueous solution. An increase in the composition ratio of the metal-coordination units from 10 mol% to 34 mol% (HPMC-34) increased the cross-linking rate with Au. Cross-linking immediately occurred after dropwise addition of an HPMC-34 solution to the Au solution, generating the separation between the phases of HPMC-34 and Au. The cross-linking of Au proceeded from the surface to the inside of the HPMC-34 droplets, affording spherical gels. In contrast, a decrease in the ratio of metal-coordination units from 10 mol% to 4 mol% (HPMC-4) decreased the Pd cross-linking rate. The cross-linking occurred gradually and the gels extended to the bottom of the vessel, forming fibrous gels. On the basis of the mechanism for the formation of gels with different morphologies, the gelation of HPMC-34 and Au provided nanosheets via gelation at the interface between the Au solution and the HPMC-34 solution. The gelation of HPMC-4 and Pd afforded nanofibers by a facile method, i.e., dropwise addition of the HPMC-4 solution to the Pd solution. These results demonstrated that changing the composition ratio of the metal-coordination units in HPMC can control the gelation behavior, resulting in different types of nanomaterials.
我们研究了带有金属配位单元的亲水性聚合物（羟丙基甲基纤维素，HPMC）与金属离子（钯或金）的凝胶化过程。凝胶化是通过将HPMC在N-甲基-2-吡咯烷酮（NMP）中的溶液滴加到金属离子水溶液中来实现的。金属配位单元的组成比例从10 mol%增加到34 mol%（HPMC-34）时，与金的交联速率提高。将HPMC-34溶液滴加到金溶液中后立即发生交联，导致HPMC-34相和金相分离。金的交联从HPMC-34液滴的表面向内部进行，形成球形凝胶。相比之下，金属配位单元的比例从10 mol%降低到4 mol%（HPMC-4）时，钯的交联速率降低。交联逐渐发生，凝胶延伸到容器底部，形成纤维状凝胶。基于不同形态凝胶形成的机理，HPMC-34与金的凝胶化通过在金溶液和HPMC-34溶液的界面处凝胶化提供了纳米片。HPMC-4与钯的凝胶化通过一种简便的方法，即将HPMC-4溶液滴加到钯溶液中，得到了纳米纤维。这些结果表明，改变HPMC中金属配位单元的组成比例可以控制凝胶化行为，从而产生不同类型的纳米材料。
