Self-Assembly of Partially Charged Diblock Copolymer-Homopolymer Ternary Blends

Abstract

Ternary blends comprising a diblock copolymer and the corresponding homopolymers provide ready access to a variety of morphologies, but the impact of charge on their phase behavior has not been studied extensively. Here, three partially charged ternary blends consisting of symmetric poly[(oligo(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) propyl sodium sulfonate methacrylate)] (POEGMA#), polystyrene (PS), and POEGMA#-PS with different charge fractions were prepared, where # denotes the mole fraction of charged monomers in the POEGMA chain. The phase behavior was systematically studied using small-angle X-ray scattering, and isothermal phase diagrams at 120 °C were constructed. The resulting isothermal planes contain a wide lamellar phase window with a slight deviation from symmetry for ion-containing ternary blends due to the homopolymer size difference. Given the absence of any significant change in the phase diagrams as the charge fraction increases, the role of charge is primarily to increase the segregation strength in the ternary system, as in the case of partially charged diblock polymers. In addition, examination of the increase in domain size along the volumetrically symmetric isopleth reveals a "dry-brush"like swelling behavior of homopolymers in all three blends, presumably due to the space-filling nature of the oligomeric ethylene glycol side chains on POEGMA.

Photocrosslinkable Polymeric Bicontinuous Microemulsions

“…Additionally, the molecular weight ratio of the homopolymer components to the diblock polymer (α) substantially influences the phase behavior of ternary blends and is represented by the following expression: α = N normalH , av N DB where N H,av is the average volumetric degree of polymerization of the homopolymers and N DB is the volumetric degree of polymerization of the diblock polymer; N = M n /( N A ρ v ) where M n is the number average degree of polymerization, N A is the Avogadro constant, ρ is the polymer density, and v is the reference volume (0.100 nm 3 ). As the mean-field Lifshitz point occurs only when α < 1, we targeted α = 0.28 in this system, consistent with several previous studies. ,, …”

“…It is also apparent that, at grain boundaries, lamellar layers smoothly transition to BμE with few defects. Notably, while BμE/LAM coexistence has been repeatedly found in A/B/AB ternary blends, ,,, this work presents the first detailed image of the morphology in this system where both phases are unambiguously present, allowing elucidation of structural details that are not apparent in SAXS alone.…”

“…This peak weakly persists in the opaque blends (ϕ H = 0.88–0.90), suggesting 3-phase coexistence between macrophase-separated PM-rich and PHC-rich domains and a BμE. At 85 and 115 °C, LAM/BμE coexistence appears from ϕ H = 0.78–0.80 as indicated by the presence of a high- q shoulder on the BμE peak (e.g., the peak at q = 0.0118 Å –1 for ϕ H = 0.80 in Figure ), a feature that has also been observed in neutral and partially charged ternary blends.…”

“…As the mean-field Lifshitz point occurs only when α < 1, 54 we targeted α = 0.28 in this system, consistent with several previous studies. 19,21,24 Phase Behavior of Ternary Blends. The full phase behavior of homopolymer/homopolymer/diblock polymer ternary blends is captured by a 4-parameter phase prism, where the relative compositions of the two homopolymers and the diblock polymer compose a ternary phase diagram and temperature is the vertical axis.…”

Structure and Phase Behavior of Bottlebrush Diblock Copolymer-Linear Homopolymer Ternary Blends

“…29−34 While BμE phases have been successfully realized with outstanding conductivity compared to non-cocontinuous phases, they appear to vanish at high ion contents (or higher segregation strength). 34,41 This is consistent in part with the aforementioned theoretical prediction that macrophase separation replaces BμE at high segregation strength due to a weak attraction between diblock monolayers. 38,39 This feature would limit high χ systems to relatively low molecular weights in order to avoid phase coexistence, resulting in small domain sizes and poor mechanical properties, although mechanical properties could be improved by selective cross-linking.…”