Influence of particle size and tunable interactions on isotropic-nematic transition of block copolymer single crystal platelet suspensions

doi:10.1016/j.jcis.2013.08.054

CORC > 化学研究所 > 中国科学院化学研究所

	Influence of particle size and tunable interactions on isotropic-nematic transition of block copolymer single crystal platelet suspensions
	Jiang, Chunbo 1,2; Huang, Haiying 1,2; Ma, Cungui 1,2; He, Tianbai 1,2; Zhang, Fajun 3
刊名	JOURNAL OF COLLOID AND INTERFACE SCIENCE
	2013-12-01
卷号	411 页码:53-60
关键词	Plate-like Particle Suspension Sedimentation Nematic Liquid Crystal Block Copolymer
ISSN号	0021-9797
DOI	10.1016/j.jcis.2013.08.054
英文摘要	We have studied the influence of the particle size and the tunable lateral interactions on the isotropic-nematic (I-N) phase transition of a plate-like colloidal system. The particles are single crystals of a block copolymer PS-b-PLLA (BCSC) prepared using a self-seeding procedure. These lozenge shape crystals have a uniform thickness and a narrowly distributed lateral size. The equilibrium phase behavior and I-N phase transition have been characterized using crossed polarizers at the room temperature. A nematic phase exists for all systems with size ranging from 700 to 4000 nm. For smaller crystals (<1200 nm), the I-N phase transition follows a process of slow sedimentation and subsequent macroscopic phase separation, resulting in a highly oriented nematic phase with a sharp I-N interface. For larger crystals (>= 1200 nm), the I-N phase transition follows a process of nucleation and subsequent sedimentation, resulting in a random orientation of crystals in the nematic phase and a rough I-N interface. The I-N transition occurs at a very low volume fraction (<0.2%) for all systems, which is at least one order of magnitude lower than the theoretical prediction (2-7%). However, addition of a small amount of ethanol into the solution, the I-N transition can be significantly suppressed. These results demonstrate the existence of a lateral attraction between crystals, which is due to the polar attraction between the uncovered PLLA crystalline domains. Polar ethanol molecules can adsorb to the PLLA crystalline surface and screen the attraction. The attraction exhibits highly orientation-dependent. To further demonstrate this highly directional attraction, we have prepared two composite single crystal suspensions with PLLA homopolymer, which have a much wider open angle for the polar attraction. Indeed, the resulting liquid crystalline phases show much less horizontal ordering. (C) 2013 Elsevier Inc. All rights reserved.
语种	英语
出版者	ACADEMIC PRESS INC ELSEVIER SCIENCE
WOS记录号	WOS:000326135600008
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/46463]
专题	中国科学院化学研究所
通讯作者	He, Tianbai
作者单位	1.Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Peoples R China 2.Univ Chinese Acad Sci, Beijing 10039, Peoples R China 3.Univ Tubingen, Inst Angew Phys, D-72076 Tubingen, Germany
推荐引用方式 GB/T 7714	Jiang, Chunbo,Huang, Haiying,Ma, Cungui,et al. Influence of particle size and tunable interactions on isotropic-nematic transition of block copolymer single crystal platelet suspensions[J]. JOURNAL OF COLLOID AND INTERFACE SCIENCE,2013,411:53-60.
APA	Jiang, Chunbo,Huang, Haiying,Ma, Cungui,He, Tianbai,&Zhang, Fajun.(2013).Influence of particle size and tunable interactions on isotropic-nematic transition of block copolymer single crystal platelet suspensions.JOURNAL OF COLLOID AND INTERFACE SCIENCE,411,53-60.
MLA	Jiang, Chunbo,et al."Influence of particle size and tunable interactions on isotropic-nematic transition of block copolymer single crystal platelet suspensions".JOURNAL OF COLLOID AND INTERFACE SCIENCE 411(2013):53-60.