Ternary Polymer Blends as Model Surfactant Systems

Abstract

An investigation of the ternary phase prism for low molecular weight poly(ethylene oxide), squalane, and poly(ethylene oxide-b-ethylenepropylene) is presented. Comparisons are made between this ternary polymer system and classic water/oil/surfactant mixtures to establish further a universal phase diagram description for amphiphilic systems. A combination of visual isothermal measurements, small-angle X-ray scattering, smallangle neutron scattering, and dynamical mechanical spectrometry was used to characterize phases and determine phase boundaries. A rich phase diagram was revealed, including most of the equilibrium liquid crystalline phases associated with diblock copolymers, regions of two-phase and three-phase coexistence, and a bicontinuous microemulsion. Differences between this polymer phase diagram and those from water/oil/ surfactant systems highlight the strong effect of water in the latter.

Lithium Salt-Induced Microstructure and Ordering in Diblock Copolymer/Homopolymer Blends

“…A value of f a = −1 indicates that the system is lamellar, while a value of f a = 0 corresponds to the crossover at which the spontaneous formation of interface is no longer energetically favorable. 21,22,51 Thus, a value of the amphiphilicity factor close to −1 indicates that the system is highly structured but still globally disordered.…”

“…In such blends, the domains of the lamellae-forming diblock swell with the addition of the homopolymers, increasing the characteristic length scale. 21 At a homopolymer loading near that of the predicted Lifshitz composition, it is hypothesized that the bending energy of the interface becomes comparable to the energy of thermal fluctuations in the system, and the lamellae give way to a bicontinuous microemulsion (BμE) morphology, which consists of cocontinuous domains that are locally correlated but globally disordered. 20 This phase behavior appears to be universal and has been seen in a large number of polymer blends.…”

Approach to block entropy modeling and optimization

“…see the phase ternary diagrams, corresponding to mixtures, in: Ref. [45].) However, extracting the optimal partition between or upon the persistent modes is not the only case.…”

Morphology and Properties of Novel Blends Prepared from Simultaneous In Situ Polymerization and Compatibilization of Macrocyclic Carbonates and Maleated Poly(propylene)

“…The extruded samples were microtomed to thicknesses less than 100 nm, and stained for 30 min with OsO 4 . This staining step provided electron scattering contrast between the polycarbonate and poly(propylene) domains.…”