Influence of conformational change of chain unit on the intrinsic negative thermal expansion of polymers  

作　　者：Qiangsheng Sun Ke Jin Yuhui Huang Jia Guo Thanyada Rungrotmongkol Phornphimon Maitarad Changchun Wang 

机构地区：[1]State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science,Fudan University,Shanghai 200433.China [2]Biocatalyst and Environmental Biotechnology Research Unit,Department of Biochemistry,Faculty of Science and Program in Bioinformatics and Computational Biology,Graduate School,Chulalongkom University,Bangkok 10330,Thailand [3]Research Center of Nano Science and Technology,Shanghai University,Shanghai 200444,China

出　　处：《Chinese Chemical Letters》2021年第4期1515-1518,共4页中国化学快报（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos.51633001,51721002 and 51873040);National Key R&D Program of China (No.2016YFC1100300)。

摘　　要：Negative thermal expansion(NTE) behavior has roused wide interest for the control of thermomechanical properties of functional materials.Although NTE behaviors have been found in kinds of compounds,it remains challenging for polymers to achieve intrinsic NTE property.In this work,we systematically studied the conformational change of dibenzocyclooctadiene(DBCOD) derivatives between chair(C) and twist-boat(TB) forms based on density-functional theo ry(DFT) calculations,and found clear evidence of the relationship between the structure of DBCOD units and the thermal contraction behavior of the related polymers.In order to obtain the polymer with NTE property,two conditions should be met for the thermal contracting DBCOD related units as follows:(i) the TB conformation can turn into C conformation as the temperature increases,and(ii) the volume of C conformation is smaller than that of TB conformation.This rule should offer a guidance to exploration of the new intrinsic NTE polymers in the future.

关 键 词：Negative thermal expansion Conformational change Polyarylamides Density-functional theory Dibenzocyclooctadiene 

分 类 号：TQ317[化学工程—高聚物工业]