Browsing by Author "Murphy, Elizabeth A"

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    Supporting Data for Cylinders-in-Undulating-Lamellae Morphology from ABC Bottlebrush Block Terpolymers
    (2025-01-06) Cui, Shuquan; Murphy, Elizabeth A; Zhang, Wei; Zografos, Aristotelis; Shen, Liyang; Bates, Frank S; Lodge, Timothy P; lodge@umn.edu; Lodge, Timothy P; University of Minnesota Department of Chemistry
    Block polymer self-assembly affords a versatile bottom-up strategy to develop materials with desired properties dictated by specific symmetries and dimensions. Owing to distinct properties compared with linear counterparts, bottlebrush block polymers with side chains densely grafted on a backbone have attracted extensive attention. However, the morphologies found in bottlebrush block polymers so far are limited, and only lamellar and cylindrical ordered phases have been reported in diblock bottlebrushes. The absence of complex morphologies such as networks might originate from the intrinsically stiff backbone architecture. We experimentally investigated the morphologies of non-frustrated ABC bottlebrush block terpolymers, based on two chemistries, poly(ethylene-alt-propylene)-b-polystyrene-b-poly(DL-lactic acid) (PEP-PS-PLA) and PEP-b-PS-b-poly(ethylene oxide) (PEP-PS-PEO) synthesized by ring-opening metathesis polymerization of norbornene-terminated macromonomers. Structural characterization based on small-angle X-ray scattering and transmission electron microscopy measurements revealed an unprecedented cylinders-in-undulating-lamellae (CUL) morphology with p2 symmetry, for both systems. Additionally, automated liquid chromatography was employed to fractionate the PEP-PS-PLA bottlebrush polymer, leading to fractions with a spectrum of morphologies, including the CUL. These findings underscore the significance of macromolecular dispersity in nominally narrow dispersity bottlebrush polymers, while demonstrating the power of this fractionation technique.
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    Supporting Data for Mesoscopic Morphologies in Frustrated ABC Bottlebrush Block Terpolymers
    (2025-02-03) Cui, Shuquan; Murphy, Elizabeth A; Santra, Subrata; Bates, Frank S; Lodge, Timothy P; lodge@umn.edu; Lodge, Timothy P; University of Minnesota Department of Chemistry
    Bottlebrush block polymers, characterized by densely grafted side chains extending from a backbone, have recently garnered significant attention. A particularly attractive feature is the accessibility of ordered morphologies with domain spacings exceeding several hundred nanometers, a capability that is challenging to achieve with linear polymers. These large morphologies make bottlebrush block polymers promising for various applications, such as photonic crystals. However, the structures observed in AB diblock bottlebrushes are generally limited to simple lamellae and cylindrical phases, which restricts their use in many applications. In this study, we synthesized a large library of 50 ABC bottlebrush triblock terpolymers, poly(DL-lactide)-b-poly(ethylene-alt-propylene)-b-polystyrene (PLA-PEP-PS), spanning a wide range of compositions using ring-opening metathesis polymerization (ROMP) of norbornene-functionalized macromonomers. This constitutes a frustrated system, in that the mandatory internal interfaces (PLA/PEP) have larger interfacial energies than PLA/PS. We systematically explored phase behavior using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Morphological characterization revealed a series of intriguing mesoscopic structures, including layered microstructures, core-shell hexagonally packed cylinders (CSHEX, plane group p6mm), alternating tetragonally packed cylinders (ATET, plane group p4mm), and an unprecedented morphology, rectangular centered cylinders-in-undulating-lamellae (RCCUL, plane group c2mm). Adjustments in molecular weight resulted in a wide range of unit cell dimensions (exemplified by RCCUL), from 40 nm to over 130 nm. This work demonstrates that multiblock bottlebrushes offer promising opportunities for developing materials with novel diverse structures and a broad range of domain dimensions.