Phase Behavior of Diblock Copolymer–Homopolymer Ternary Blends: Congruent First-Order Lamellar–Disorder Transition

Abstract

We have established the existence of a line of congruent first-order lamellar-to-disorder (LAM–DIS) transitions when appropriate amounts of poly­(cyclohexyl­ethylene) (C) and poly­(ethylene) (E) homopolymers are mixed with a corresponding compositionally symmetric CE diblock copolymer. The line of congruent transitions, or the congruent isopleth, terminates at the bicontinuous microemulsion (BμE) channel, and its trajectory appears to be influenced by the critical composition of the C/E binary homopolymer blend. Blends satisfying congruency undergo a direct LAM–DIS transition without passing through a two-phase region. We present complementary optical transmission, small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and dynamic mechanical spectroscopy (DMS) results that establish the phase behavior at constant copolymer volume fraction and varying C/E homopolymer volume ratios. Adjacent to the congruent composition at constant copolymer volume fraction, the lamellar and disordered phases are separated by two-phase coexistence windows, which converge, along with the line of congruent transitions, at an overall composition in the phase prism coincident with the BμE channel. Hexagonal and cubic (double gyroid) phases occur at higher diblock copolymer concentrations for asymmetric amounts of C and E homopolymers. These results establish a quantitative method for identifying the detailed phase behavior of ternary diblock copolymer–homopolymer blends, especially in the vicinity of the BμE.

Nanostructure stability and swelling of ternary block copolymer/homopolymer blends: A direct comparison between dissipative particle dynamics and experiment

“…DPD has also been shown to reproduce experimental morphology shifts in A‐ b ‐B/A and A‐ b ‐B/C binary BCP/HP blends. In contrast to mean field theories (MFTs), which neglect thermal fluctuations, DPD simulations predict the formation of a βμE phase in symmetric ternary blends, consistent with the experimental observation. We note that field theoretic simulations also find a βμE phase in ternary blends, but always in coexistence with A and B homopolymer phases .…”

Controlling nanostructure and mechanical properties in triblock copolymer/monomer blends via reaction-induced phase transitions

“…24 In situ polymerization methods resulting in a variety of block polymer topologies (linear or grafted) have demonstrated the usefulness of RIPT as a means to control nanostructure during bulk polymerizations as opposed to simply blending block polymers and homopolymers. [25][26][27] The synthesis of HIPS is an excellent example of the in situ process of creating graft copolymers during the polymerization of styrene in the presence of poly(butadiene) (PBD). The formation of graft copolymers is a result of using a radical generator that creates allylic radicals along the PBD backbone, leading to the formation of poly(styrene) (PS) grafted from PBD.…”

High-throughput morphology mapping of self-assembling ternary polymer blends

“…14,15,[30][31][32][33][34][35] The combination of enhanced ordering kinetics with reduced domain spacing makes blending of wet brush homopolymers especially appealing for nanolithographic applications, motivated by decreased dimensions required by continued device scaling 3,5 or patterned magnetic media. 36 Blending is also a powerful approach to rationally control self-assembled nanodomain morphology, 35,[37][38][39][40][41] in some cases obtaining ordered morphologies that are inaccessible using neat (unblended) BCPs. 13,[42][43][44][45][46] Considering the advantages of using wet brush homopolymers, however, investigations of their morphological behavior in ternary blends with BCPs have been relatively rare.…”