【13th.Jan.】The phase behavior of polymer blends under shear field
日期：2017-01-13
閱讀：911
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TOPIC：The phase behavior of polymer blends under shear field
SPEAKER：郭洪霞研究員，中科院北京化學(xué)研究所
TIME：January 13 (Friday) 9:30 am
LOCATION：Room 528, Chemistry Building A (化學(xué)A樓528演講廳)
INVITER：俞煒 教授?
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The phase behavior of polymer blends under shear field
Hongxia Guo
State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
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Abstract
Polymer blending is a simple and efficient means to create high performance materials. However, in most cases, the miscibility between different polymers is rather low; homopolymer blends are therefore unstable and tend to macroscopically phase separate into their own domains, which weakens the interfacial adhesion and results in poor mechanical performances. Adding block copolymers or nanoparticles is a straightforward approach to stabilize the immiscible polymers. There has been substantial work on exploring their rich equilibrium phase behavior in the past and a very well understanding has been achieved by today In addition, there is much current interest in nonequilibrium behavior of these complex fluids i.e., under shear flow.
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In the present work, we study the phase behavior of sheared ternary systems, which contains symmetric AB block copolymers or nanoparticles with different surface properties and geometric shapes in a symmetric blend of A and B homopolymers.?
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We found that the statically stable bicontinuous microemulsions (BuE ) are unstable under shear flow, which can be transformed to the ordered lamellar phase (LAM) or the macroscopically separated phase (2P) depending on the shear rate and the location of phase state relative to the static 2P-BuE boundary as well as surface properties of nanoparticles. Particularly, unlike in the shear-free case, the shear –induced formation of lamellar phase is independent of the shape and dividing surface design of Janus nanoparticles. When comparing among the samples with added block copolymers and added nanoparticles with the amphiphilic characteristics (that is Janus nanoparticles), due to the difference in the interfacial elasticity, the former samples exhibit the sheared-induced parallel to perpendicular orientation transition in lamellar phase upon increasing the shear rate as well as the sheared-induced lamellar-2P transition, while in the latter systems the parallel lamellae remain stable under shear field. These results shed light in unveiling the underlying mechanisms for shear effect on the complex fluids with different morphologies.
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Biography
郭洪霞，中國科學(xué)院化學(xué)研究所高分子物理與化學(xué)國家重點(diǎn)實(shí)驗(yàn)室研究員，博士生導(dǎo)師。1996年于中國科學(xué)院物理研究所獲凝聚態(tài)物理博士學(xué)位，1996.09-2000.09年在中國科學(xué)院化學(xué)研究所任助理研究員、副研究員, 2000.09-2004.02年在德國馬普高分子研究所從事博士后研究， 2004.03-2005.12年，在美國西北大學(xué)材料科學(xué)與工程系高級(jí)研究員。2006年01月回國在中國科學(xué)院化學(xué)研究所高分子物理與化學(xué)國家重點(diǎn)實(shí)驗(yàn)室工作，2007年入選中國科學(xué)院 “百人計(jì)劃”人才項(xiàng)目。近年主要從事軟物質(zhì)體系的理論計(jì)算與模擬, 在發(fā)展有效模型、建立多尺度模擬方法、和開發(fā)高性能模擬算法等方面取得了系列重要研究成果，并對(duì)高分子及其復(fù)雜體系的相行為和動(dòng)力學(xué)、界面性質(zhì)與界面行為、取向和流變學(xué)性質(zhì)進(jìn)行了深入研究。近五年來在ACSNano, SoftMatter, nanotechnology, PCCP等核心期刊發(fā)表文章50余篇。主持或參加國家自然科學(xué)基金項(xiàng)目五項(xiàng)、科技部973項(xiàng)目和國家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目各一項(xiàng)。
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