Coherent crystal branches: the impact of tetragonal symmetry on the 2D confined polymer nanostructure

IUCrJ

Hui Niu¹  Shuailin Zhang²  Ziying Liang³  Yan Cao³  Ziwei Lai³  Bo Ni⁴  Nan Zheng⁵ 

[1] Department of Polymer Science and Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China;Department of Polymer Science, The University of Akron, Akron, OH 44325, USA;Institute for Advanced Study, Shenzhen University, Guangdong 518060, People's Republic of China;South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, People's Republic of China;State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangdong 513060, People's Republic of China;

关键词: cylindrical confinement;    coherent crystal branch;    tetragonal crystal;    poly(4-methyl-1-pentene);   

DOI  :  10.1107/S2052252521000774

来源: DOAJ

【 摘 要 】

The symmetry of polymer crystals greatly affects the optical, thermal conductivity and mechanical properties of the materials. Past studies have shown that the two-dimensional (2D) confined crystallization of polymer nanorods could produce anisotropic structures. However, few researchers have focused on understanding confined nanostructures from the perspective of crystal symmetry. In this research, we demonstrate the molecular chain self-assembly of tetragonal crystals under cylindrical confinement. We specifically selected poly(4-methyl-1-pentene) (P4MP1) with a 41 or 72 helical conformation (usually crystallizing with a tetragonal lattice) as the model polymer. We found a coherent crystal branching of the tetragonal crystal in the P4MP1 nanorods. The unusual 45°- and 135°-{200} diffractions and the meridional 220 diffraction (from 45°-tilted crystals) have shown a uniform crystal branching between the a1-axis crystals and the 45°-tilted crystals in the rod long axis, which originates from a structural defect associated with tetragonal symmetry. Surprisingly, this chain packing defect in the tetragonal cell can be controlled to develop along the rod long axis in 2D confinement.

【 授权许可】

Unknown