Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, 14513 Teltow, Germany.
Proc Natl Acad Sci U S A. 2013 Jul 30;110(31):12555-9. doi: 10.1073/pnas.1301895110. Epub 2013 Jul 8.
Reading out the temperature-memory of polymers, which is their ability to remember the temperature where they were deformed recently, is thus far unavoidably linked to erasing this memory effect. Here temperature-memory polymer actuators (TMPAs) based on cross-linked copolymer networks exhibiting a broad melting temperature range (ΔT(m)) are presented, which are capable of a long-term temperature-memory enabling more than 250 cyclic thermally controlled actuations with almost constant performance. The characteristic actuation temperatures T(act)s of TMPAs can be adjusted by a purely physical process, guiding a directed crystallization in a temperature range of up to 40 °C by variation of the parameter T(sep) in a nearly linear correlation. The temperature T(sep) divides ΔT(m) into an upper T(m) range (T > T(sep)) forming a reshapeable actuation geometry that determines the skeleton and a lower T(m) range (T < T(sep)) that enables the temperature-controlled bidirectional actuation by crystallization-induced elongation and melting-induced contraction. The macroscopic bidirectional shape changes in TMPAs could be correlated with changes in the nanostructure of the crystallizable domains as a result of in situ X-ray investigations. Potential applications of TMPAs include heat engines with adjustable rotation rate and active building facades with self-regulating sun protectors.
读取聚合物的温度记忆，即它们记住最近变形温度的能力，目前不可避免地与消除这种记忆效应有关。本文介绍了基于交联共聚网络的具有较宽熔融温度范围（ΔTm）的温度记忆聚合物致动器（TMPA），它能够实现长期的温度记忆，超过 250 次循环的热控制致动，性能几乎保持不变。TMPA 的特征致动温度 Tact 可以通过纯物理过程进行调节，通过参数 Tsep 的变化，在高达 40°C 的温度范围内引导定向结晶，呈近线性相关。温度 Tsep 将ΔTm 分为上 Tm 范围（T>Tsep），形成可重塑的致动几何形状，决定了骨架，以及下 Tm 范围（T<Tsep），通过结晶诱导伸长和熔融诱导收缩实现温度控制的双向致动。TMPA 的宏观双向形状变化可以与可结晶域的纳米结构变化相关联，这是原位 X 射线研究的结果。TMPA 的潜在应用包括可调节转速的热机和具有自调节遮阳板的主动建筑外墙。
