Dual-shape properties of triple-shape polymer networks with crystallizable network segments and grafted side chains
Dual-shape properties of triple-shape polymer networks with crystallizable network segments and grafted side chains
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DOI：
10.1039/b702524f
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发表时间：
2007-01-01
影响因子：
--
通讯作者：
Lendlein, Andreas
中科院分区：
文献类型：
--
作者：
Bellin, Ingo;Kelch, Steffen;Lendlein, Andreas
三重形状材料最近被引入作为一类有前景的活性聚合物，其可以根据需要从第一形状（A）改变为第二形状（B），并从第二形状改变为第三形状（C）。在这里，这样的三重形状的聚合物网络系统具有两个不同的熔融转变的双重形状的能力进行了研究，通过循环，热机械实验。这些多相聚合物网络是由聚（乙二醇）单甲基醚单甲基丙烯酸酯和聚（ε-己内酯）二甲基丙烯酸酯作为交联剂通过光聚合合成的。虽然它们的永久形状是由网络制备过程中形成的化学交联决定的，但这两种不同的可结晶相可用于固定其他临时形状。当在两步热机械过程中适当编程时，这些材料可以表现出三重形状效应。在这里，一步编程方法的双重形状的影响下，这些聚合物网络的工艺参数的变化，特别是热条件。以这种方式，由两个区段形成的结晶相可以单独或同时用于固定临时的第二形状。永久形状可以通过加热恢复，超过特定的转换温度。如果一个结构域用于固定，则该转换温度与相关结构域的熔融转变相关。如果使用两种结构域，则转换温度与较高的熔融温度相关。
Triple-shape materials have recently been introduced as a promising class of active polymers, that can change on demand from a first shape (A) to a second shape (B) and from there to a third shape (C). Here, the dual-shape capability of such a triple-shape polymer network system having two distinct melting transitions is investigated by cyclic, thermomechanical experiments. These multiphase polymer networks are synthesized by photopolymerization from poly(ethylene glycol) monomethyl ether monomethacrylate and poly(epsilon-caprolactone) dimethacrylate as crosslinker. While their permanent shape is determined by the chemical crosslinks formed during network preparation, the two different crystallizable phases can be used to fix other temporary shapes. When programmed appropriately in a two-step thermomechanical process these materials can exhibit a triple-shape effect. Here, one-step programming methods for dual-shape effects are applied to these polymer networks under variation of process parameters, especially thermal conditions. In this way, crystalline phases formed by both segments can be used either individually or simultaneously to fix a temporary second shape. The permanent shape can be recovered by heating, exceeding a specific switching temperature. This switching temperature correlates with the melting transition of the related domain, if one domain is used for fixation. If both domains are used, the switching temperature correlates with the higher melting temperature.