Phase Transition of Block Copolymer/Homopolymer Binary Blends under 2D Confinement

다국어 초록 (Multilingual Abstract)

Constraints imposed by nanometer scale confinement lead to the changes in bulk equilibrium behavior of block copolymers (BCPs). Cylindrical pores with diameter corresponding to the equivalent length of several copolymer chains have been employed to investigate the influence of two-dimensional (2D) confinement on the behavior of BCPs. Herein, we reported the microdomain transition behavior of block copolymer/homopolymer (AB/A) binary blends in cylindrical confinement.
Lamellae forming poly(styrene-b-butadiene) (PS-b-PBD) and PS homopolymers (hPS) were drawn into the pores of anodized aluminum oxide (AAO) and isolated by selective etching of the AAO templates. Concentric ring morphologies of neat PS-b-PBD in the cylindrical confinement varied with on the addition of hPS. Given the volume fraction of homopolymers, the phase behavior of polymer blends was dependent on the molecular weight of homopolymers. When the ratio between the molecular weight of hPS and PS block was much lower than unity (α«1) (i.e., wet brush regime), the concentric ring structure was transformed into helical or spherical structure depending on the volume fraction of hPS. For α≈1 (i.e., dry brush regime), additional hPS chains were localized at the center of concentric ring where the entropic penalty of copolymer chains induced by confinement is maximized. Over the capability of hPS in the BCP domains in radial axis, the phase transition into microemulsions occurred in the dry brush regime. In both wet and dry brush regimes, the effect of hPS on the phase transition of BCP was significantly enhanced in the nanoscale 2D confinement compared to the bulk state due to the loss of conformational entropy of polymer chains.

참고문헌 (Reference)

1 A. K. Khandpur, 28 : 8796-, 1995

2 H. Ahn, 53 : 5163-, 2012

3 R. J. Albalak, 32 : 341-, 1994

4 P. W. Majewski, 50 : 2-, 2012

5 J. Y. Cheng, 3 : 823-, 2004

6 S. H. Kim, 16 : 226-, 2004

7 P. Mansky, 30 : 6810-, 1997

8 R. A. Segalman, 13 : 1152-, 2001

9 H. S. Suh, 43 : 461-, 2010

10 X. M. Yang, 33 : 9575-, 2000

11 P. Dobriyal, 42 : 9082-, 2009

12 K. Shin, 306 : 76-, 2004

13 Y. Sun, 26 : 369-, 2005

14 K. M. Coakley, 83 : 3380-, 2003

15 Y. Kang, 6 : 957-, 2007

16 C. Park, 44 : 6725-, 2003

17 T. Hashimoto, 23 : 4378-, 1990

18 M. W. Matsen, 28 : 5765-, 1995

19 K. I. Winey, 25 : 2645-, 1992

20 K. -J. Jeon, 27 : 2439-, 1994

21 U. Nagpal, 5 : 5673-, 2011

22 M. P. Stoykovich, 97 : 147802-, 2006

23 M. P. Stoykovich, 308 : 1442-, 2005

24 J. Xu, 31 : 10975-, 2015

25 R. Yang, 28 : 1569-, 2011

26 J. Xu, 31 : 12354-, 2015

27 R. Furneaux, 337 : 147-, 1989

28 A. Li, 84 : 6023-, 1998

29 H. Masuda, 268 : 1466-, 1995

30 B. Yu, 41 : 4042-, 2008

31 B. Yu, 96 : 138306-, 2006

32 H. Tanaka, 24 : 240-, 1991

33 S. Koizumi, 27 : 6532-, 1994

34 M. W. Matsen, 29 : 1091-, 1996