Operando Investigation of the Molecular Origins of Dipole Switching in P(VDF‐TrFE‐CFE) Terpolymer for Large Adiabatic Temperature Change
Operando Investigation of the Molecular Origins of Dipole Switching in P(VDF‐TrFE‐CFE) Terpolymer for Large Adiabatic Temperature Change
复制标题
DOI：
10.1002/adfm.202314705
复制
发表时间：
2024-02
影响因子：
19
通讯作者：
Yuan Zhu;Hanxiang Wu;Andrew Martin;Paige Beck;E. Allahyarov;Thumawadee Wongwirat;Guanchun Rui;Yingke Zhu;Daniel Hawthorne;Jiacheng Fan;Jianghan Wu;Siyu Zhang;Lei Zhu;Sumanjeet Kaur;Qibing Pei
中科院分区：
文献类型：
--
作者：
Yuan Zhu;Hanxiang Wu;Andrew Martin;Paige Beck;E. Allahyarov;Thumawadee Wongwirat;Guanchun Rui;Yingke Zhu;Daniel Hawthorne;Jiacheng Fan;Jianghan Wu;Siyu Zhang;Lei Zhu;Sumanjeet Kaur;Qibing Pei
表现出巨大电热效应（ECE）的弛豫铁电聚合物可以潜在地用于创建下一代固态冷却器。在电场作用下，聚（偏二氟乙烯-三氟乙烯-氯氟乙烯）乙烯发生大的偶极熵变，产生高的绝热温度变化（ΔTECE）。这项工作解决了电场诱导偶极开关背后的大熵变的分子起源。用配有高压电源的傅里叶变换红外光谱仪对分子的特征振动模式进行了随机观测。CF2-CH 2二联体的短程反式（T）构象被一个左式（G）构象中断，例如，当施加电场时，Δ TTG链中的TTTG经历动态变换，导致相应的ΔTECE。分子动力学模拟也证明了从TTTG到长T序列的转变所克服的能垒比所有其他构象都要小。使用混合溶剂体系来获得在60 MV m-1下表现出4.02 K ΔTECE的富含T3 G的叠层膜，并且使用这些膜来制造实现6.7 K温升的2层级联冷却装置，这是由含氟聚合物制成的2层级联装置的最高报告值。
Relaxor ferroelectric polymers exhibiting a giant electrocaloric effect (ECE) can potentially be used to create next‐generation solid‐state coolers. Under an electric field, poly(vinylidene fluoride‐trifluoroethylene‐chlorofluoroethylene) terpolymer goes through a large dipolar entropy change producing a high adiabatic temperature change (ΔTECE). This work resolves the molecular origins of the large entropy change behind the electric field‐induced dipole switching. A Fourier transform infrared spectroscopy equipped with a high voltage source is used to operandoly observe the characteristic molecular vibrational modes. A short‐range trans (T) conformation of the CF2‐CH2 dyads interrupted by a gauche (G) conformation, e.g., TTTG in the terpolymer chain, undergoes a dynamic transformation that leads to a corresponding ΔTECE whenever an electric field is applied. The molecular dynamics simulation also proves that the energy barrier that the transformation from TTTGs into a long T sequence overcomes is smaller than that for all other conformations. A mixed solvent system is used to obtain T3G‐enriched terpolymer films exhibiting a 4.02 K ΔTECE at 60 MV m−1 and these films are employed to manufacture a 2‐layer‐cascaded cooling device that achieves a 6.7 K temperature lift, the highest reported value for a 2‐layer cascaded device made of fluoropolymers.