Alignment of lamellar diblock copolymer phases under shear:: Insight from dissipative particle dynamics simulations

被引:53
|
作者
Lisal, Martin [1 ]
Brennan, John K.
机构
[1] Acad Sci Czech Republ, Inst Chem Proc Fundamentals, E Hala Lab Thermodynam, CR-16502 Prague 6, Czech Republic
[2] USA, Res Lab, Weapons & Mat Res Directorate, Aberdeen Proving Ground, MD 21005 USA
关键词
D O I
10.1021/la063095c
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Sheared self-assembled lamellar phases formed by symmetrical diblock copolymers are investigated through dissipative particle dynamics simulations. Our intent is to provide insight into the experimental observations that the lamellar phases adopt parallel alignment at low shear rates and perpendicular alignment at high shear rates and that it is possible to use shear to induce a transition from the parallel to perpendicular alignment. Simulations are initiated either from lamellar structures prepared under zero shear where lamellae are aligned into parallel, perpendicular, or transverse orientations with respect to the shear direction or from a disordered melt obtained by energy minimization of a random structure. We first consider the relative stability of the parallel and perpendicular phases by applying shear to lamellar structures initially aligned parallel and perpendicular to the shear direction, respectively. The perpendicular lamellar phase persists for all shear rates investigated, whereas the parallel lamellar phase is only stable at low shear rates, and it becomes unstable at high shear rates. At the high shear rates, the parallel lamellar phase first transforms into an unstable diagonal lamellar phase; and upon further increase of the shear rate, the parallel lamellar phase reorients into a perpendicular alignment. We further determine the preferential alignment of the lamellar phases at low shear rate by performing the simulations starting from either the initial transverse lamellar structure or the disordered melt. Since the low shear-rate simulations are plagued by the unstable diagonal lamellar phases, we vary the system size to achieve the natural spacing of the lamellae in the simulation box. In such cases, the unstable diagonal lamellar phases disappear and lamellar phases adopt the preferential alignment, either parallel or perpendicular. In agreement with the experimental observations, the simulations show that the lamellar phase preferentially adopts the parallel orientation at low shear rates and the perpendicular orientation at high shear rates. The simulations further reveal that the perpendicular lamellar phase has lower internal energy than the parallel lamellar phase, whereas the entropy production of the perpendicular lamellar phase is higher with respect to the parallel lamellar phase. Values of the internal energy and entropy production for the unstable diagonal lamellar phases lie between the corresponding values for the parallel and perpendicular lamellar phases. These simulation results suggest that the relative stability of the parallel and perpendicular lamellar phases at low shear rates is a result of the interplay between competing driving forces in the system: (a) the system's drive to adopt a structure with the lowest internal energy and (b) the system's drive to stay in a stationary nonequilibrium state with the lowest entropy production.
引用
收藏
页码:4809 / 4818
页数:10
相关论文
共 50 条
  • [1] Dissipative particle dynamics study on the morphology changes of diblock copolymer lamellar microdomains due to steady shear
    Liu, Wei
    Qian, Hu-Jun
    Lu, Zhong-Yuan
    Li, Ze-Sheng
    Sun, Chia-Chung
    [J]. PHYSICAL REVIEW E, 2006, 74 (02)
  • [2] Steady and oscillatory shear flow alignment dynamics in a lamellar diblock copolymer solution
    Zryd, JL
    Burghardt, WR
    [J]. MACROMOLECULES, 1998, 31 (11) : 3656 - 3670
  • [3] Dissipative particle dynamics study on morphology changes of cyclic diblock copolymer microphase under shear
    Liu Wei
    Qian Ha-Jun
    Lu Zhong-Yuan
    Li Zhuo
    Sun Chia-Chung
    [J]. CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE, 2007, 28 (03): : 548 - 551
  • [4] Tilted Lamellar Phase of the Rod–Coil Diblock Copolymer: Dissipative Particle Dynamics Simulation
    A. V. Berezkin
    Y. V. Kudryavtsev
    M. A. Osipov
    [J]. Polymer Science, Series A, 2020, 62 : 430 - 436
  • [5] Dynamics of shear alignment in a lamellar diblock copolymer: Interplay of frequency, strain amplitude, and temperature
    Gupta, VK
    Krishnamoorti, R
    Chen, ZR
    Kornfield, JA
    Smith, SD
    Satkowski, MM
    Grothaus, JT
    [J]. MACROMOLECULES, 1996, 29 (03) : 875 - 884
  • [6] Tilted Lamellar Phase of the Rod-Coil Diblock Copolymer: Dissipative Particle Dynamics Simulation
    Berezkin, A., V
    Kudryavtsev, Y., V
    Osipov, M. A.
    [J]. POLYMER SCIENCE SERIES A, 2020, 62 (04) : 430 - 436
  • [7] Self-Assembly of Lamellar- and Cylinder-Forming Diblock Copolymers in Planar Slits: Insight from Dissipative Particle Dynamics Simulations
    Petrus, Pavel
    Lisal, Martin
    Brennan, John K.
    [J]. LANGMUIR, 2010, 26 (18) : 14680 - 14693
  • [8] Effect of shear on the symmetric diblock copolymer/nanorod mixture:A dissipative particle dynamics study
    何林李
    张瑞芬
    季永运
    [J]. Chinese Physics B, 2012, 21 (08) : 553 - 563
  • [9] Effect of shear on the symmetric diblock copolymer/nanorod mixture: A dissipative particle dynamics study
    He Lin-Li
    Zhang Rui-Fen
    Ji Yong-Yun
    [J]. CHINESE PHYSICS B, 2012, 21 (08)
  • [10] Kinetics of Diblock Copolymer Micellization by Dissipative Particle Dynamics
    Li, Zhenlong
    Dormidontova, Elena E.
    [J]. MACROMOLECULES, 2010, 43 (07) : 3521 - 3531