Epitaxial Phase Transition between Double Gyroid and Cylinder Phase in Diblock Copolymer Thin Film

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• 作者：Jueun Jung ; Junyoung Lee ; Hae-Woong Park ; Taihyun Chang ; Hidekazu Sugimori ; Hiroshi Jinnai
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：December 23, 2014
• 年：2014
• 卷：47
• 期：24
• 页码：8761-8767
• 全文大小：548K
• ISSN：1520-5835

文摘

The epitaxial relationship in the thermal phase transition between double gyroid (DG) and hexagonally packed cylinder (HEX) phases in polystyrene-block-polyisoprene thin films on Si wafer was investigated using transmission electron microtomography and grazing incidence small-angle X-ray scattering. Two different types of epitaxial transitions were observed, and they appeared to be selectively favored depending on the transition direction. One type of epitaxial relationship prevails in the phase transition from DG to HEX upon heating in which {121}_DG, {111}_DG, and {220}_DG are converted to {100}_HEX, {110}_HEX, and {001}_HEX, respectively. The interphase planes are {220}_DG and {001}_HEX, and the cylinders meet the {220}_DG plane perpendicularly (head-on, Type A) at the grain boundary between DG and HEX. Although there are small dimensional mismatch and distortion in the location of the cylinders in this epitaxial relationship, all cylinders are formed along the topologically equivalent DG skeletal path. On the other hand, in the transition from HEX to DG upon cooling, another epitaxial relationship as well as the head-on type epitaxy was observed, in which {100}_HEX, {110}_HEX, and {001}_HEX are converted to {121}_DG, {220}_DG, and {111}_DG, respectively. The interphase planes are {220}_DG and {110}_HEX, and the cylinders meet the {220}_DG plane in parallel (side-on, Type B) at the grain boundary between HEX and DG. The domain spacing and the symmetry of the two phases are matched near perfectly, but cylinders are converted to two different DG skeletal paths. The Type B epitaxy is hardly observed in the transition from DG to HEX.