Wood Technology and Wood Chemistry, University of Goettingen, Büsgenweg 4, D-37077, Göttingen, Germany.
Third Institute of Physics-Biophysics, Faculty of Physics, University of Goettingen, Friedrich-Hund-Platz 1, D-37077, Göttingen, Germany.
Macromol Rapid Commun. 2019 Oct;40(19):e1900317. doi: 10.1002/marc.201900317. Epub 2019 Aug 21.
Controlling water transportation within hydrogels makes hydrogels attractive for diverse applications, but it is still a very challenging task. Herein, a novel type of dually electrostatically crosslinked nanocomposite hydrogel showing thermoresponsive water absorption, distribution, and dehydration processes are developed. The nanocomposite hydrogels are stabilized via electrostatic interactions between negatively charged poly(acrylic acid) and positively charged layered double hydroxide (LDH) nanosheets as well as poly(3-acrylamidopropyltrimethylammonium chloride). Both LDH nanosheets as crosslinkers and the surrounding temperatures played pivotal roles in tuning the water transportation within these nanocomposite hydrogels. By changing the surrounding temperature from 60 to 4 °C, these hydrogels showed widely adjustable swelling times between 2 and 45 days, while the dehydration process lasted between 7 and 27 days. A swift temperature decrease, for example, from 60 to 25 °C, generated supersaturation within these nanocomposite hydrogels, which further retarded the water transportation and distribution in hydrogel networks. Benefiting from modified water transportation and rapidly alternating water uptake capability during temperature change, pre-loaded compounds can be used to track and visualize these processes within nanocomposite hydrogels. At the same time, the discharge of water and loaded compounds from the interior of hydrogels demonstrates a thermoresponsive sustained release process.
控制水凝胶中的水传输使水凝胶在各种应用中具有吸引力，但这仍然是一项极具挑战性的任务。在此，开发了一种新型的双重静电交联纳米复合水凝胶，其具有温敏性吸水、分布和脱水过程。纳米复合水凝胶通过带负电荷的聚丙烯酸与带正电荷的层状双氢氧化物（LDH）纳米片以及聚（3-丙烯酰胺丙基三甲基氯化铵）之间的静电相互作用稳定。LDH 纳米片作为交联剂和周围温度在调节这些纳米复合水凝胶内的水传输中起着关键作用。通过将环境温度从 60°C 改变到 4°C，这些水凝胶的溶胀时间在 2 到 45 天之间具有广泛的可调性，而脱水过程持续 7 到 27 天。例如，从 60°C 快速降至 25°C 会在这些纳米复合水凝胶内产生过饱和度，从而进一步减缓水凝胶网络中的水传输和分布。受益于改性的水传输和在温度变化期间快速交替的吸水能力，可以将预加载的化合物用于跟踪和可视化纳米复合水凝胶内的这些过程。同时，水和负载化合物从水凝胶内部的排出显示出温敏性持续释放过程。
