Structural Evolution of Polyelectrolyte Complex Core Micelles and Ordered-Phase Bulk Materials

Journal Article · Mon Nov 24 23:00:00 EST 2014 · Macromolecules

DOI:https://doi.org/10.1021/ma5017852· OSTI ID:1352844

Krogstad, Daniel V.; Lynd, Nathaniel A.; Miyajima, Daigo; Gopez, Jeffrey; Hawker, Craig J.; Kramer, Edward J.; Tirrell, Matthew V.

The kinetics of formation and structural evolution of novel polyelectrolyte complex materials formed by the assembly of water-soluble di- and triblock copolymers, with one neutral block and one (or two) cationic or anionic blocks, have been investigated. Comparison was made between the assembly of ABA and AB? copolymers in which A represents the ionic blocks and B and B' are the neutral poly(ethylene oxide) blocks. The degree of polymerization of B was twice that of B? and the ionic A blocks were of equal degrees of polymerization in all polymers. The mechanism and speed of the assembly process, and the organization of these domains, was probed using dynamic mechanical spectroscopy and small-angle X-ray scattering (SAXS). SAXS revealed that the equilibrium morphologies of both the diblock copolymer and the triblock copolymer materials were generally qualitatively the same with some apparent quantitative differences in phase boundaries, possibly attributable to lack of full equilibration. Slow kinetics and difficulties in reaching equilibrium phase structures, especially in triblock materials, is a principal message of this article. Detailed analysis of the SAXS data revealed that the triblock copolymer materials formed ordered phases via a nucleation and growth pathway and that the addition of small amounts (similar to 20%) of corresponding diblock copolymers increased the rate of structure formation and enhanced several key physical properties.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division; National Science Foundation (NSF); USDOE Office of Science - Office of Basic Energy Sciences - Scientific User Facilities Division; USDOE Office of Science - Office of Basic Energy Sciences
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1352844
• Journal Information: Macromolecules, Journal Name: Macromolecules Journal Issue: 22 Vol. 47; ISSN 0024-9297
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English