High Resolution NMR Centre (HNMR), Department of Materials and Chemistry (MACH), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium.
Chemistry. 2011 Dec 23;17(52):14867-77. doi: 10.1002/chem.201101334. Epub 2011 Oct 27.
(1)H HRMAS NMR spectroscopy is applied to gain insight into the chemical and morphological structure of double-network (DN) hydrogels, prepared from poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and poly(acrylamide) (PAAm). The method enables one to obtain detailed information at the molecular level about the formation of covalent bonds between the two polymer networks through non-reacted double bonds of the cross-linker N,N'-methylene bis(acrylamide) (MBAA). Evidence to the existence of strong hydrogen-bond interactions based on the N-H group of the PAMPS as a hydrogen-bond donor and the C=O group of the PAAm as a hydrogen-bond acceptor is also provided. These findings clarify the origin of the toughening mechanism and the exceptionally strong mechanical properties of DN gels, further supported by microhardness data.
（1）高分辨率魔角旋转核磁共振波谱学（HRMAS NMR spectroscopy）被应用于深入研究由聚（2-丙烯酰胺基-2-甲基-1-丙磺酸）（PAMPS）和聚丙烯酰胺（PAAm）制备的双网络（DN）水凝胶的化学和形态结构。该方法能够在分子水平上获得关于两个聚合物网络之间通过交联剂 N,N'-亚甲基双（丙烯酰胺）（MBAA）的未反应双键形成共价键的详细信息。还提供了基于 PAMPS 的 N-H 基团作为氢键供体和 PAAm 的 C=O 基团作为氢键受体的强氢键相互作用存在的证据。这些发现阐明了 DN 凝胶增韧机制和异常强机械性能的起源，进一步得到了显微硬度数据的支持。
