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Park, Soojin
Nano-Functional Materials Lab
Research Interests
  • Block Copolymers, nanostructured materials for Lithium-Ion batteries, wearable and stretchable energy storage applications

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Unusual sensitivity of closed-loop phase Behavior to chain size and distribution

Cited 3 times inthomson ciCited 2 times inthomson ci
Title
Unusual sensitivity of closed-loop phase Behavior to chain size and distribution
Author
Hwang, Sung WookKim, EunhyeShin, ChanghakKim, Jung HyunRyu, Du YeolPark, SoojinChang, T.Kim, J. K.
Keywords
GRADIENT INTERACTION CHROMATOGRAPHY; CRITICAL ORDERING TRANSITION; MASS-SPECTROMETRY ANALYSIS; LATTICE CLUSTER THEORY; BLOCK-COPOLYMER; DIBLOCK COPOLYMERS; DISORDER TRANSITION; POLYMER BLENDS; THERMODYNAMICS; BIREFRINGENCE
Issue Date
200710
Publisher
AMER CHEMICAL SOC
Citation
MACROMOLECULES, v.40, no.22, pp.8066 - 8070
Abstract
An anionically polymerized polystyrene-block-poly(n-pentyl methacrylate) (PS-b-PnPMA) was fractionated by interaction chromatography (IC), and the closed-loop phase behavior of the mother block copolymer and its fractions with different chemical compositions was investigated by depolarized light scattering and polarized optical microscopy. With increasing elution time the average chain size (or the average molecular weight) of the block copolymer decreased slightly, and the average chemical composition changed steadily from a PS volume fraction of 0.583 to 0.403, thereby producing five fractions collected over the different ranges of elution time. This is caused by the difference of relative interaction strength between the stationary phase and the PnPMA chains of PS-b-PnPMA, in which PnPMA chains tend to be adsorbed onto the stationary phase while PS chains behave oppositely. Over the range of accessible temperatures studied (110-250°C) a variety of phase transitions were observed, including fully ordered state, a closed-loop (consisting of the lower disorder-to-order transition and upper order-to-disorder transition), and fully disordered state. The original, unfractionated block copolymer was disordered over the entire temperature range. The variety of observed phase transitions obtained from the fractionated block copolymers is assumed to be governed by the sensitivity of the closed-loop phase behavior to average chain size, average chemical composition, and the compositional broadness.
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DOI
http://dx.doi.org/10.1021/ma071314a
ISSN
0024-9297
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