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dc.contributor.authorXiong, Huiming
dc.contributor.authorChen, Chun-Ku
dc.contributor.authorLee, Kyungmin
dc.contributor.authorVan Horn, Ryan M.
dc.contributor.authorLiu, Zheng
dc.contributor.authorRen, Bin
dc.contributor.author任斌
dc.contributor.authorQuirk, Roderic P.
dc.contributor.authorThomas, Edwin L.
dc.contributor.authorLotz, Bernard
dc.contributor.authorHo, Rong-Ming
dc.contributor.authorZhang, Wen-Bin
dc.contributor.authorCheng, Stephen Z. D.
dc.date.accessioned2012-02-22T07:00:17Z
dc.date.available2012-02-22T07:00:17Z
dc.date.issued2011-09-12
dc.identifier.citationMacromolecules, 2011, 44 (19): 7758–7766zh_CN
dc.identifier.issn0024-9297
dc.identifier.urihttp://dx.doi.org/doi:10.1021/ma201325t
dc.identifier.urihttps://dspace.xmu.edu.cn/handle/2288/11484
dc.identifier.uriWOS:000295487600032
dc.description.abstractTo understand the formation mechanism of nonflat polymer single crystals, two types of triblock copolymers with a middle crystalline block and two amorphous, immiscible end-blocks were designed and synthesized. Specifically, polystyrene-block-poly(ethylene oxide)-block-poly(1-butene oxide) and polystyrene-block-poly(ethylene oxide)-block-polydimethylsiloxane were examined. When the end-blocks possess different volumes and are microphase separated onto the opposite sides of the single crystal lamella formed by the middle crystalline block, unbalanced surface stress can be generated. As a result, large scrolled single crystals (similar to 80 mu m) were grown from dilute solution using the self-seeding procedure at low supercoolings. The scrolling direction was identified to be along the, (120) planes based on transmission electron microscopy (TEM) observations of the sedimented scrolled single crystals, which is in line with the fact that the scrolling occurs along the planes with the highest coefficient of thermal expansion. Using high-resolution TEM at high tilting angles, three layers of distinct chemical compositions can be clearly identified from the edges of the single crystals after RuO(4) staining. It suggests the formation of microphase separated domains of the amorphous end-blocks on the opposite sides of PEO single crystals. Although the tethering densities of these amorphous end-blocks are identical, their reduced tethering densities are different, resulting in dissimilar volumes and surface crowdedness on the opposite sides of PEO single crystal. The unbalanced surface stress is thus generated to scroll the lamellar single crystal. Macroscopically, based on the observed curvature and the assumption of a solid plate cylinder, the strain energy for each individual single crystal with lateral size of 80 mu m was estimated to be similar to 3 x 10(-9) erg, which, though small, is sufficient to maintain the scrolling of single crystal in solution at room temperature (the thermal energy is approximately kT similar to 4 x 10(-14) erg). Microscopically, the difference of the reduced surface free energy of the tethered blocks at the opposite sides of the PEO lamellar single crystal is analyzed and understood to be the driving force of the scrolling.zh_CN
dc.description.sponsorshipNSF[DMR-0516602, DMR-0906898]zh_CN
dc.language.isoenzh_CN
dc.publisherAMER CHEMICAL SOCzh_CN
dc.titleScrolled Polymer Single Crystals Driven by Unbalanced Surface Stresses: Rational Design and Experimental Evidencezh_CN
dc.typeArticlezh_CN


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