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Quadruple-shape hydrogels

机译：四重形状水凝胶

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The capability of directed movements by two subsequent shape changes could be implemented in shape-memory hydrogels by incorporation of two types of crystallizable side chains While in non-swollen polymer networks even more directed movements could be realized, the creation of multi-shape hydrogels is still a challenge. We hypothesize that a quadruple-shape effect in hydrogels can be realized, when a swelling capacity almost independent of temperature is generated, whereby directed movements could be enabled, which are not related to swelling. In this case, entropy elastic recovery could be realized by hydrophilic segments and the fixation of different macroscopic shapes by means of three semi-crystalline side chains generating temporary crosslinks. Monomethacrylated semi-crystalline oligomers were connected as side chains in a hydrophilic polymer network via radical copolymerization. Computer assisted modelling was utilized to design a demonstrator capable of complex shape shifts by creating a casting mold via 3D printing from polyvinyl alcohol. The demonstrator was obtained after copolymerization of polymer network forming components within the mold, which was subsequently dissolved in water. A thermally-induced quadruple-shape effect was realized after equilibrium swelling of the polymer network in water. Three directed movements were successfully obtained when the temperature was continuously increased from 5 degrees C to 90 degrees C with a recovery ratio of the original shape above 90%. Hence, a thermally-induced quadruple-shape effect as new record for hydrogels was realized. Here, the temperature range for the multi-shape effect was limited by water as swelling media (0 degrees C-100 degrees C), simultaneously distinctly separated thermal transitions were required, and the overall elasticity indispensable for successive deformations was reduced as result of partially chain segment orientation induced by swelling in water. Conclusively the challenges for penta- or hexa-shape gels are the design of systems enabling higher elastic deformability and covering a larger temperature range by switching to a different solvent.
机译：通过两个后续形状改变的定向运动的能力可以通过在形状 - 存储器水凝胶中实现，其通过在非膨胀的聚合物网络中掺入甚至可以实现更多定向的运动，所以多形水凝胶的产生是仍然是一个挑战。我们假设可以实现水凝胶中的四重形状效果，当产生几乎独立于温度的膨胀容量时，可以使能导向运动，这与膨胀无关。在这种情况下，可以通过亲水区段和不同的宏观形状的固定来实现熵弹性回收，并通过三个半结晶侧链产生临时交联。单甲基丙烯酸酯化的半结晶低聚物通过自由基共聚合在亲水性聚合物网络中作为侧链连接。计算机辅助建模用于设计能够通过从聚乙烯醇的3D印刷形成铸造模具来设计能够复杂形状的演示器。在模具内的聚合物网络形成组分的共聚合之后获得了示范器，随后将其溶于水中。在水中平衡聚合物网络的平衡后实现了热诱导的四重形状效果。当温度从5摄氏度升高到90℃以上的恢复比以上90％以上时，成功获得了三种定向运动。因此，实现了作为水凝胶新记录的热诱导的四重形状效应。这里，多形效果的温度范围受水的限制为膨胀介质（0℃-100摄氏度），同时需要独特的分离的热转变，并且由于部分的结果而导致连续变形的总体弹性不可或缺。通过在水中溶胀引起的链段取向。结论，五边形或六缘形凝胶的挑战是通过切换到不同的溶剂来实现更高的弹性变形性并覆盖较大温度范围的系统的设计。

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