Thermoreversible Supramolecular Polymer Gels via Metal-Ligand Coordination in an Ionic Liquid
Thermoreversible Supramolecular Polymer Gels via Metal-Ligand Coordination in an Ionic Liquid
复制标题
DOI：
10.1021/ma401820x
复制
发表时间：
2013-10
期刊：
影响因子：
5.5
通讯作者：
Atsushi Noro;S. Matsushima;Xudong He;Mikihiro Hayashi;Y. Matsushita
中科院分区：
文献类型：
--
作者：
Atsushi Noro;S. Matsushima;Xudong He;Mikihiro Hayashi;Y. Matsushita
以1-乙基-3-甲基咪唑双（三氟甲基磺酰基）酰亚胺为疏水离子液体，通过金属配位法制备了热可逆的超分子聚合物凝胶。FT-IR光谱显示，即使在离子液体中，ZnCl2中的锌与吡啶基团之间的金属配位也作为配体存在于P4VP块上。温度斜坡振荡剪切测量证实了半固态（凝胶状）和液态之间的热可逆粘弹性特性。研究还发现，超分子聚合物凝胶的热可逆性强烈依赖于配体与金属之间的化学计量，当可用配位位点的摩尔量达到一定的过量（配位位点/配体比~…）时，作为凝胶化指标的存储模量-损失模量交叉温度（Tgel）达到最大值。
Thermoreversible supramolecular polymer gels were prepared via metal–ligand coordination by mixing a poly(4-vinylpyridine)-b-poly(ethyl acrylate)-b-poly(4-vinylpyridine) (P4VP–PEA–P4VP) triblock copolymer and zinc chloride (ZnCl2) in a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imidide. FT-IR spectroscopy revealed metal–ligand coordination between zinc in ZnCl2 and pyridine groups as ligands on P4VP blocks, even in an ionic liquid. Thermoreversible viscoelastic properties between a semisolid (gel-like) state and a liquid-like state were confirmed by temperature-ramp oscillatory shear measurements. It was also revealed that thermoreversibility of supramolecular polymer gels depended strongly on stoichiometry between ligands and metals, where the maximum of storage modulus-loss modulus crossover temperature (Tgel) as an indicator of gelation was achieved when a molar amount of available coordination sites was a certain excessive amount (coordination site/ligand ratio ∼...