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yexuqing木虫之王 (文学泰斗)
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用溶剂增韧的玻璃状凝胶
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用溶剂增韧的玻璃状凝胶 ▲ 作者：Meixiang Wang, Xun Xiao, Salma Siddika, Mohammad Shamsi, Ethan Frey, Wen Qian, Wubin Bai, Brendan T. O’Connor & Michael D. Dickey ▲链接： https://www.nature.com/articles/s41586-024-07564-0 ▲摘要： 玻璃状聚合物通常坚硬而坚固，但延展性有限。通过溶胀，玻璃状聚合物可以变成柔软而脆弱的凝胶，但具有增强的延展性。性能的显著变化是由于溶剂增加了链间的自由体积，同时减弱了聚合物与聚合物之间的相互作用。研究者展示了极性聚合物与离子液体——离子凝胶，在适当浓度下的溶剂化可以产生一种独特的材料，称为玻璃凝胶，具有玻璃和凝胶的理想性能。 离子液体增加了自由体积，因此，尽管缺乏传统的溶剂(例如，水)，可扩展性。但在室温下，离子液体在聚合物链之间形成强而丰富的非共价交联，形成坚硬、坚韧、玻璃状和均匀的网络(即没有相分离)。尽管液体含量超过54wt %，但玻璃凝胶具有巨大的断裂强度(42 MPa)、韧性(110 MJ m?3)、屈服强度(73 MPa)和杨氏模量(1 GPa)。这些值与热塑性塑料(如聚乙烯)相似，但与热塑性塑料不同的是，玻璃状凝胶可以变形到670%的应变，并且在加热时可以完全快速恢复。这些透明材料通过一步聚合形成，具有令人印象深刻的粘合、自愈和形状记忆特性。 ▲ Abstract： Glassy polymers are generally stiff and strong yet have limited extensibility. By swelling with solvent, glassy polymers can become gels that are soft and weak yet have enhanced extensibility. The marked changes in properties arise from the solvent increasing free volume between chains while weakening polymer–polymer interactions. Here we show that solvating polar polymers with ionic liquids (that is, ionogels) at appropriate concentrations can produce a unique class of materials called glassy gels with desirable properties of both glasses and gels. The ionic liquid increases free volume and therefore extensibility despite the absence of conventional solvent (for example, water). Yet, the ionic liquid forms strong and abundant non-covalent crosslinks between polymer chains to render a stiff, tough, glassy, and homogeneous network (that is, no phase separation), at room temperature. Despite being more than 54wt% liquid, the glassy gels exhibit enormous fracture strength (42 MPa), toughness (110 MJ m?3), yield strength (73 MPa) and Young’s modulus (1 GPa). These values are similar to those of thermoplastics such as polyethylene, yet unlike thermoplastics, the glassy gels can be deformed up to 670% strain with full and rapid recovery on heating. These transparent materials form by a one-step polymerization and have impressive adhesive, self-healing and shape-memory properties. |
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