High-throughput morphology mapping of self-assembling ternary polymer blends. Issue 69 (24th November 2020)

• Record Type: Journal Article
• Authors: Toth, Kristof; Osuji, Chinedum O.; Yager, Kevin G.; Doerk, Gregory S.
• Is Part Of: RSC advances. Volume 10:Issue 69(2020)
• Page Start: 42529
• Page End: 42541
• Publication Date: 2020-11-24
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d0ra08491c
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Compositionally graded electrospray deposition combined with grazing incidence small angle X-ray scattering forms a high-throughput approach for mapping phase behavior in ternary mixtures as demonstrated here using block copolymer blends. Abstract : Multicomponent blending is a convenient yet powerful approach to rationally control the material structure, morphology, and functional properties in solution-deposited films of block copolymers and other self-assembling nanomaterials. However, progress in understanding the structural and morphological dependencies on blend composition is hampered by the time and labor required to synthesize and characterize a large number of discrete samples. Here, we report a new method to systematically explore a wide composition space in ternary blends. Specifically, the blend composition space is divided into gradient segments deposited sequentially on a single wafer by a new gradient electrospray deposition tool, and characterized using high-throughput grazing-incidence small-angle X-ray scattering. This method is applied to the creation of a ternary morphology diagram for a cylinder-forming polystyrene- block -poly(methyl methacrylate) (PS- b -PMMA) block copolymer blended with PS and PMMA homopolymers. Using "wet brush" homopolymers of very low molecular weight (∼1 kg mol −1 ), we identify well-demarcated composition regions comprising highly ordered cylinder, lamellae, and sphere morphologies, as well as a disordered phase at high homopolymer mass fractions. The exquisite granularity afforded by this approach also helps to uncover systematic dependencies among self-assembled morphology, topological grain size, and domain period as functions of homopolymer mass fraction and PS : PMMA ratio. These results highlight the significant advantages afforded by blending low molecular weight homopolymers for block copolymer self-assembly. Meanwhile, the high-throughput, combinatorial approach to investigating nanomaterial blends introduced here dramatically reduces the time required to explore complex process parameter spaces and is a natural complement to recent advances in autonomous X-ray characterization.