Tunable Thermal Switch via Order-Order Transition in Liquid Crystalline Block Copolymer.
basic_science · Level V
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- Record sourced from PubMed, PMID 35883274.
- Also identified by DOI 10.1021/acs.nanolett.2c01100.
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Abstract
Organic material-based thermal switch is drawing much attention as one of the key thermal management devices in organic electronic devices. This study aims at tuning the switching temperature (<i>T</i><sub>S</sub>) of thermal conductivity by using liquid crystalline block copolymers (BCs) with different order-order transition temperature (<i>T</i><sub>tr</sub>) related to the types of mesogens in the side chain. The BC films with low <i>T</i><sub>tr</sub> of 363 K and high <i>T</i><sub>tr</sub> of 395 K exhibit reversible thermal conductivity switching behaviors at <i>T</i><sub>S</sub> of ∼360 K and ∼390 K, respectively. The BC films also exhibit thermal conductivity variation originating from the anisotropy of the internal structures: poly(ethylene oxide) domains and liquid crystals. These results demonstrate that the switching behavior is attributed to an order-order transition between BC films with vertically arranged cylinder domains and the ones with ordered sphere domains. This highlights that BCs become a promising thermal conductivity switching material with tailored <i>T</i><sub>S</sub>.