Polymer blends thermodynamics

It is known that, in a polymer blend, thermodynamic incompatibility between polymers usually causes demixing of polymers. If the polymer is equilibrated in air, the polymer with the lowest surface energy (hydrophobic polymer) will concentrate at the air interface and reduce the system s interfacial tension as a consequence. The preferential adsorption of a polymer of lower surface tension at the surface was confirmed by a number of researchers for a miscible blend of two different polymers. Based on this concept, surface modifying macromolecules (SMMs) as surface-active additives were synthesized and blended into polymer solutions of polyethersulfone (PES). Depending on the hydro-phobic or hydrophilic nature of the SMM, the membrane surface becomes either more hydrophobic or more hydrophilic than the base polymeric material. ... 

In the early years (prior to 1980), the effect of deuterium substitution on polymer blend thermodynamics was assumed to be negligible. In a pioneering publication, Buckingham and Hentschel [43] estimated x between protonated and deuterated polymers that are otherwise identical (isotopic blends) to be about 10 . They thus came to the surprising conclusion that isotopic blends should be phase separated at modest molecular weights (V IO ). Elegant experimental proof for this effect was provided by Bates and CO workers [44]. 

Similar to polymer blends, thermodynamically stable moleculaj composites could be achieved by favorable interactions by balancing the unfavorable entropic contributions to the free energy of mixing. Indeed, it is unlikely to overcome the immiscibility by dipole-dipole interactions, and therefore it has been suggested to introduce hydrogen bonding or ionic interactions. 

POLYMER BLEND THERMODYNAMICS FLORY HUGGINS THEORY AND ITS APPLICATION TO EXCIMER FLUORESCENCE STUDIES... 

Multicomponent polymer blends can offer a vast array of possible morphologies. Three factors can have an important effect on morphology formation in immiscible multicomponent polymer blends thermodynamic properties of the blend, and more specifically the interfacial tensions of the different polymer pairs [1-5] viscosity of the constituents [6] and elasticity of the constituents [7, 8]. 

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