Acid-base interactions compatibility

Compatible Polyblends. When the polymeric materials are compatible in all ratios, and/or all are soluble in each other, they are generally termed polyalloys. Very few pairs of polymers are completely compatible. The best known example is the polyblend of polyCphenylene oxide) (poly-2,6-dimethyl-l,4-phenylene oxide) with high-impact polystyrene (41). which is sold under the trade name of Noryl. It is believed that the two polymers have essentially identical solubility parameters. Other examples include blends of amorphous polycaprolactone with poly(vinyl chloride) (PVC) and butadiene/acrylonitrile rubber with PVC the compatibility is a result of the "acid-base" interaction between the polar substituents (1 ). These compatible blends exhibit physical properties that are intermediate to those of the components. 

The adhesion of paint films is influenced primarily by the chemical composition of the binder. Films may adhere by a mix of all possible mechanisms, for example. Dispersion forces, Acid-base interactions. Hydrogen bonding, covalent bond formation and other specific chemical interactions, such as chelation. In addition to these molecular interactions across an interface, the micro-roughness of the substrate can contribute by increasing the surface area and points of contact (see Mechanical theory of adhesion). In addition, if the substrate is itself another paint film (or a plastic), chain ends of the overcoating polymer can diffuse into the substrate, provided that the binder types are mutually compatible (see Theories of adhesion). 

The wetting kinetics of sized glass fibers by melt changed due to acid-base interactions and compatibility between the film former and surrounding bulk polymer matrix. The highest interfacial shear strength values corresponded to the... 

In the formulation of any pharmaceutical product, it is imperative to ensure that the ingredients used are compatible with one another. Incompatibilities can occur between drug and excipient as well as between the excipients themselves. Incompatibilities may be manifested through many modes, such as acid-base interaction and complex formation, resulting in lower potency and/or stability and eventually poor therapeutic efficacy of the product. It is therefore essential to avoid incompatibilities and this is achieved by carrying out studies to detect potential interactions between the components used in the formulation. 

Having found the proton carrier, the next step is to find a suitable host polymer that possesses the appropriate thermal stability and compatibility with phosphoric acid in the desired temperature range. Using a basic polymer is a general practice via acid-base interactions with the acid. For this, the most successful polymers are PBIs, a large family of heterocyclic polymers with excellent thermal, chemical, and mechanical stabilities. PBI variants, their blends as well as analogues such as pyridine containing aromatic polymers are chosen as the focal point of this book. 

In contrast to the Nafion-FEP system, in which the immiscibility of the polymer components is clearly shown in Fig. 14.8, greater compatibility of Nafion and polybenzimidazole (PBI) was expected due to acid-base interactions between imidazole nitrogens and sulfonic acid protons. PBI should function in such a system as a crosslinker (see Fig. 14.15), producing a reduction in membrane swelling and permeability by methanol. Although the idea of examining acid-base membrane blends in fuel cells is not new [9,11-13,30], little work has been carried out with Nafion. 

For the acid-base interaction in solutions, in 1963, Pearson proposed the hard-soft acid-base (HSAB) principle to describe some basic rules about the kinetics and equilibrium of the reaction. In this paper, we attempt to apply the HSAB principle to solid interactions with the aid of the frontier orbital method. We shall first describe the HSAB principle as it has been evolved in recent years " and then the band structures of solids. After we demonstrate the compatibility between the HSAB principle and the band structures in the solid state, we then illustrate with several examples of adhesion and tribointeractions between metals and... 

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