The utility of thermoresponsive hydrogels, such as those based on poly(N‐isopropylacrylamide) (PNIPAAm), is severely limited by their deficient mechanical properties. In particular, the simultaneous achievement of high strength and stiffness remains unreported. In this work, a thermoresponsive hydrogel is prepared having the unique combination of ultrahigh compressive strength (≈23 MPa) and excellent compressive modulus (≈1.5 MPa). This is accomplished by employing a double network (DN) design comprised of a tightly crosslinked, highly negatively charged 1st network based on poly(2‐acrylamido‐2‐methylpropane sulfonic acid (PAMPS) and a loosely crosslinked, zwitterionic 2nd network based on a copolymer of thermoresponsive NIPAAm and zwitterionic 2‐(methacryloyloxy)ethyl]dimethyl‐(3‐sulfopropyl)ammonium hydroxide (MEDSAH). Comparison to other DN designs reveals that this PAMPS/P(NIPAAm‐co‐MEDSAH) DN hydrogel's remarkable properties stem from the intra‐ and internetwork ionic interactions of the two networks. Finally, this mechanically robust hydrogel retains the desirable thermosensitivity of PNIPAAm hydrogels, exhibiting a volume phase transition temperature of ≈35 °C.

中文翻译：

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具有出色压缩机械性能的热敏性双网络水凝胶

热响应水凝胶的实用性，例如基于聚N的水凝胶-异丙基丙烯酰胺（PNIPAAm）由于其机械性能不足而受到严重限制。特别是，尚未报道同时实现高强度和刚度。在这项工作中，制备了具有超高抗压强度（约23 MPa）和优异的压缩模量（约1.5 MPa）的独特组合的热响应性水凝胶。这是通过采用双网络（DN）设计实现的，该设计包括紧密交联的，带负电的第一网络，该网络基于聚（2-丙烯酰胺基-2-甲基丙烷磺酸（PAMPS）），以及一个松散的交联的两性离子网络，其基于聚（2-丙烯酰胺基-2-甲基丙烷磺酸）。 NIPAAm和两性离子2-（甲基丙烯酰氧基）乙基]二甲基-（3-磺丙基丙基）氢氧化铵（MEDSAH）的共聚物与其他DN设计的比较表明，该PAMPS / P（NIPAAm- co‐MEDSAH）DN水凝胶的卓越性能源于两个网络的内部和网络间离子相互作用。最后，这种机械坚固的水凝胶保留了PNIPAAm水凝胶的理想热敏性，表现出约35°C的体积相变温度。