Structure and electric properties of poly(vinylidene fluoride-tetrafluoroethylene) copolymer studied with density functional theory

doi:10.1016/j.polymer.2007.09.029

	Structure and electric properties of poly(vinylidene fluoride-tetrafluoroethylene) copolymer studied with density functional theory
	Wang, Zhi-Yin 2,3; Su, Ke-He 1; Fan, Hui-Qing 2; Wen, Zhen-Yi 4
刊名	POLYMER
	2007-11-16
卷号	48 页码:7145-7155
关键词	polymer physical chemistry DFT P(VDF-TeFE)
ISSN号	0032-3861
DOI	10.1016/j.polymer.2007.09.029
英文摘要	The internal rotation, geometry, energy, vibrational spectra, dipole moments and molecular mean polarizabilities of poly(vinylidene fluoride-tetrafluoroethylene) (P(VDF-TeFE)) of alpha- and beta-chain models Were Studied with density functional theory at B3PW91/6-31 G(d) level and compared with those of poly(vinylidene fluoride) homopolymer and P(VDF-TrFE) copolymer. The electric properties, chain conformation and stability of the copolymer influenced by the chain length and TeFE content were examined. Based on the internal rotation curves of P(VDF-TeFE) dimer models (H[CH2CF2-CF2CF2]H and H[CF2CH2-CF2CF2]H), the conformational angles, relative stabilities of alpha- and beta-conformation, and the transition energy barriers of beta --> alpha and alpha --> beta were discussed. The results show that the beta-conformation is more stable than the alpha-conformation thermodynamically and the beta --> alpha transition in P(VDF-TeFE) is more difficult than that in PVDF. Thus the copolymer Should be in favor of preventing the piezoelectric phase from depolarization. The ideal beta-chains are curved with a radius of about 30 A, which is very close to those in both PVDF and P(P(VDF-TrFE). Similar to P(VDF-TrFE), the alpha-chain P(VDF-TeFE) containing 0.50 mole fraction of TeFE is also a helical Structure. However, the g.-chain with 0.33-0.20 mole fraction of TeFE are almost linear in structure, which might be responsible for enhancing crystallinity of the copolymer. The contribution of average dipole moment per monomer unit in the beta-chain is affected by the chain Curvature and TeFE content, and there is a weakly parabolic dependence on the VDF content. The chain length and TeFE content will not significantly affect the mean polarizability per monomer unit. The calculations show that there are some characteristic vibrational modes that may be used in the identification of the alpha- and beta-phase P(VDF-TeFE) with different TeFE contents. (C) 2007 Elsevier Ltd. All rights reserved.
WOS关键词	FERROELECTRIC PHASE-TRANSITION ; FLUORIDE-TRIFLUOROETHYLENE COPOLYMERS ; VINYLIDENE FLUORIDE ; OPTICAL-PROPERTIES ; CURIE TRANSITION ; POLYVINYLIDENE FLUORIDE ; CO-POLYMERS ; TETRAFLUOROETHYLENE COPOLYMERS ; VIBRATIONAL FREQUENCIES ; THERMAL CONTRACTION
WOS研究方向	Polymer Science
语种	英语
出版者	ELSEVIER SCI LTD
WOS记录号	WOS:000251815100018
内容类型	期刊论文
源URL	[http://119.78.100.186/handle/113462/28042]
专题	中国科学院近代物理研究所
通讯作者	Su, Ke-He
作者单位	1.NW Polytech Univ, Sch Nat & Appl Sci, Xian 710072, Shaanxi, Peoples R China 2.NW Polytech Univ, State Key Lab Solidificat Proc, Sch Mat Sci & Engn, Xian 710072, Shaanxi, Peoples R China 3.Shaanxi Univ Technol, Sch Chem & Environm Sci, Hanzhong 723000, Shaanxi, Peoples R China 4.NW Univ Xian, Inst Modern Phys, Xian 710068, Shaanxi, Peoples R China
推荐引用方式 GB/T 7714	Wang, Zhi-Yin,Su, Ke-He,Fan, Hui-Qing,et al. Structure and electric properties of poly(vinylidene fluoride-tetrafluoroethylene) copolymer studied with density functional theory[J]. POLYMER,2007,48:7145-7155.
APA	Wang, Zhi-Yin,Su, Ke-He,Fan, Hui-Qing,&Wen, Zhen-Yi.(2007).Structure and electric properties of poly(vinylidene fluoride-tetrafluoroethylene) copolymer studied with density functional theory.POLYMER,48,7145-7155.
MLA	Wang, Zhi-Yin,et al."Structure and electric properties of poly(vinylidene fluoride-tetrafluoroethylene) copolymer studied with density functional theory".POLYMER 48(2007):7145-7155.