Ternary Phase Behavior of a Triblock Copolymer in the Presence of an Endblock-Selective Homopolymer and a Midblock-Selective Oil

Abstract

Bicomponent block copolymers are known to exhibit rich phase behavior in systems containing one or two block-selective homopolymers or solvents. In this study, we combine these efforts by investigating ternary blends composed of an ABA triblock copolymer, an A-selective homopolymer and a Bselective oil. A styrenic thermoplastic elastomer is selected here because of its ability to form a physical network upon microphase separation and thus impart significant elasticity and toughness to such blends. Synchrotron small-angle X-ray scattering is employed to classify the nanostructures of blends varying in composition, homopolymer molecular weight, and oil type, and the results are used to construct ternary morphology diagrams that reveal the phases present at the glass transition temperature of the styrenic endblocks. Of all the classical and complex morphologies commonly observed in binary copolymer blends and solutions, only the bicontinuous gyroid consisting of styrenic channels in a mixed midblock/oil matrix is consistently absent. Variations in nanostructural dimensions with blend composition are provided for selected morphologies.

Bicomponent Block Copolymers Derived from One or More Random Copolymers as an Alternative Route to Controllable Phase Behavior

“…Due to the thermodynamic incompatibility between the covalently linked blocks, AB diblock and higher order bicomponent multiblock copolymers can spontaneously self‐assemble in the melt and order into several classical nanostructures, such as A(B) spheres positioned on a body‐ or face‐centered cubic lattice in a B(A) matrix, A(B) cylinders arranged on a hexagonal lattice in a B(A) matrix or alternating lamellae . More complex nanoscale morphologies, such as the bicontinuous gyroid, twisted helices, a Frank‐Kasper σ phase, and coexisting lamellae+spheres, have also been reported to form in neat copolymers, and many of these signature nanostructures, as well as others (e.g., bicontinuous microemulsions), have likewise been observed in block copolymers containing one or more homopolymers or solvents . In some cases, self‐assembly can be controlled and directed in block‐selective solvents by, for example, crystallization and/or chemical coordination to yield highly anisotropic nanoscale objects such as cylinders measuring more than 10 μm in length.…”

Quasi‐Solid‐State Dye‐Sensitized Solar Cells Containing a Charged Thermoplastic Elastomeric Gel Electrolyte and Hydrophilic/phobic Photosensitizers

“…Classic morphologies of bicomponent (A‐B type) block copolymers include spherical A(B) micelles positioned on a body‐ or face‐centered‐cubic lattice in a B(A) matrix, A(B) cylinders arranged on a hexagonal lattice in a B(A) matrix and alternating lamellae. More spatially complex morphologies, such as the gyroid, bicontinuous microemulsions and coexisting nanostructures, have been found to form in neat block copolymers, as well as in their blends with liquid diluents and other copolymers . In some of these morphologies, a conductive matrix or a contiguous conductive pathway naturally facilitates the diffusion of electrons to the working electrode, where they can be efficiently collected by the counter electrode .…”

Dual Self-Assembly in Strongly Asymmetric A-B-A Triblock Copolymer Melts Studied by Self-Consistent Field Theory and Monte Carlo Simulations

“…Self-assembly in the block copolymer melts is an active area of research [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Block copolymers self-assemble via the microphase separation which is an instant of the orderdisorder transition (ODT).…”