Foster Jeffrey C, Staiger Chad L, Dugger Jason W, Redline Erica M
Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
ACS Macro Lett. 2021 Jul 20;10(7):940-944. doi: 10.1021/acsmacrolett.1c00312. Epub 2021 Jul 2.
Fine control over the thermal expansion and contraction behavior of polymer materials is challenging. Most polymers have large coefficients of thermal expansion (CTEs), which preclude long performance lifetimes of composite materials. Herein, we report the design and synthesis of epoxy thermosets with low CTE values below their and large contraction behavior above by incorporating thermally contractile dibenzocyclooctane (DBCO) motifs within the thermoset network. This atypical thermomechanical behavior was rationalized in terms of a twist-boat to chair conformational equilibrium of the DBCO linkages. We anticipate these findings to be generally useful in the preparation of materials with designed CTE values.
对聚合物材料的热膨胀和收缩行为进行精确控制具有挑战性。大多数聚合物具有较大的热膨胀系数（CTE），这使得复合材料的长期性能寿命受到限制。在此，我们报告了通过在热固性网络中引入热收缩性的二苯并环辛炔（DBCO）基团，设计和合成了CTE值低于其转变温度且在该温度以上具有大收缩行为的环氧热固性材料。这种非典型的热机械行为是根据DBCO键的扭船式到椅式构象平衡来解释的。我们预计这些发现对于制备具有设计CTE值的材料将具有普遍的实用性。
