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Published December 30, 2009 | Supplemental Material
Journal Article Open

Efficient Synthesis of Narrowly Dispersed Brush Copolymers and Study of Their Assemblies: The Importance of Side Chain Arrangement


Efficient, one-pot preparation of synthetically challenging, high molecular weight (MW), narrowly dispersed brush block copolymers and random copolymers in high conversions was achieved by ring-opening metathesis (co)polymerization (ROMP) of various macromonomers (MMs) using the highly active, fast-initiating ruthenium olefin metathesis catalyst (H_2IMes)(pyr)_2(Cl)_2RuCHPh. A series of random and block copolymers were prepared from a pair of MMs containing polylactide (PLA) and poly(n-butyl acrylate) (PnBA) side chains at similar MWs. Their self-assembly in the melt state was studied by small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). In brush random copolymers containing approximately equal volume fractions of PLA and PnBA, the side chains segregate into lamellae with domain spacing of 14 nm as measured by SAXS, which was in good agreement with the lamellar thickness measured by AFM. The domain spacings and order−disorder transition temperatures of brush random copolymers were insensitive to the backbone length. In contrast, brush block copolymers containing approximately equal volume fractions of these MMs self-assembled into highly ordered lamellae with domain spacing over 100 nm. Their assemblies suggested that the brush block copolymer backbone adopted an extended conformation in the ordered state.

Additional Information

© 2009 American Chemical Society. Received October 2, 2009. Publication Date (Web): November 30, 2009. This work was supported by the Department of Energy (DE-FG02-05ER46218). We gratefully acknowledge Professor James R. Heath for the use of the AFM, Brookhaven National Lab for the use of SAXS, Lixia Rong for assistance with SAXS measurement, and Edward H. Bramston-Cook for assistance with AFM measurement. BDO thanks the Caltech Beckman Institute for a postdoctoral fellowship.

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Supplemental Material - ja908379q_si_001.pdf


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August 19, 2023
October 19, 2023