Bulk and Thin Film Morphological Behavior of Broad Dispersity Poly(styrene-b-methyl methacrylate) Diblock Copolymers

Autor:	Padma Gopalan, Mahesh K. Mahanthappa, Adam K. Schmitt, Eungnak Han, Myungwoong Kim, Joan M. Widin
Rok vydání:	2013
Předmět:	Materials science Polymers and Plastics Small-angle X-ray scattering Organic Chemistry Dispersity Methacrylate Styrene Inorganic Chemistry chemistry.chemical_compound chemistry Lamellar phase Chemical engineering Polymer chemistry Materials Chemistry Copolymer Lamellar structure Methyl methacrylate
Zdroj:	Macromolecules. 46:4472-4480
ISSN:	1520-5835 0024-9297
DOI:	10.1021/ma4004538
Popis:	We describe the morphological implications of broad molecular weight dispersity on the bulk and thin film self-assembly behavior of seven model poly(styrene-block-methyl methacrylate) (SM) diblock copolymers. Derived from sequential nitroxide-mediated polymerizations, these unimodal diblock copolymers are comprised of narrow dispersity S blocks (Đ ≤ 1.14) and broad dispersity M blocks (Đ ∼ 1.7) with total molecular weights Mn,total = 29.2–42.9 kg/mol and M volume fractions fM = 0.35–0.63. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) analyses demonstrate that these diblock copolymers microphase separate into lamellar and cylindrical morphologies with substantially larger microdomain spacings at lower overall molecular weights as compared to their narrow dispersity analogues. The observed microphase-separated melt stabilization is also accompanied by a substantial shift in the lamellar phase composition window to higher values of fM. In thin films, these polydisperse copoly...
Databáze:	OpenAIRE
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