Open AccessThin film confinement reduces compatibility in symmetric ternary block copolymer/homopolymer blends
Author(s) -
Uddin Md Fakar,
Jiang Zhang,
Raymond Andrew,
Goodson Amy D.,
Lwoya Baraka S.,
Albert Julie N. L.
Publication year - 2018
Publication title -
journal of polymer science part b: polymer physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.65
H-Index - 145
eISSN - 1099-0488
pISSN - 0887-6266
DOI - 10.1002/polb.24732
Subject(s) - materials science , copolymer , lamellar structure , morphology (biology) , polymer blend , ternary operation , thin film , x ray reflectivity , polymer chemistry , phase (matter) , wetting , elastomer , phase diagram , chemical engineering , composite material , polymer , nanotechnology , chemistry , organic chemistry , engineering , genetics , computer science , biology , programming language
The thin film phase behavior of ternary blends consisting of symmetric poly(styrene) (PS)‐ b ‐poly(dimethylsiloxane)(PDMS), PS, and PDMS was investigated using X‐ray reflectivity (XRR) and atomic force microscopy (AFM). This system is strongly segregated, and the homopolymers are approximately the same length as the corresponding blocks of the copolymer. The XRR and AFM data are used to quantify changes in domain spacing ( L ) and morphology evolution with increasing homopolymer content (Φ H ). In 100 nm thick films, from Φ H = 0 to 0.20, the system maintains a perfect parallel lamellar structure and domains swell as predicted based on theory; however, from Φ H = 0.30 to 0.50, a morphology transition to a “dot pattern” morphology (tentatively identified as perforated lamellae) and mixed morphologies were observed before macrophase separation. In thicker films, dot patterns were observed for a broad range of Φ H before macrophase separation. The absence of the bicontinuous microemulsion phase reported for bulk blends and thin films of perpendicular lamellae and the presence of dot patterns/perforated lamellae are attributed to preferential migration of the PDMS homopolymer to the wetting layers located at the substrate and free air interfaces, which leads to an asymmetric composition within the film and morphology transition. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56 , 1443–1451