Amphoteric groups

If the surface is populated with these amphoteric groups at N sites/unit area, the surface charge density of the surface is (e = protonic charge)... 

The function depends on the type of surface oxygens. For gibbsite type (amphoteric) groups a combination of Eq. (60) and (62) with = 0 can describe the local... 

Various acidic, basic and amphoteric groups can be attached to the silica surface in this way (Table 10.8). 

On the surface of crystals there are always the non-compensated charges, derived from the non-equilibrated valences of snrface atoms, as well as from the iso-morphous substitutions. Finally, they can be related to the hydrolysis of amphoteric groups (Figs. 5.13, 5.14). 

The majority of silicone polymers/surfactants that are used in today s personal care industry are of the nonionic types. Since the derivatives of polysiloxanes could be ionic completely or partially, the properties exhibited by such compounds are different and therefore provide an entirely new range of properties and benefits. For example, cationic and amphoteric functional groups, because of increased substantivity on the hair surfaces and durable surface covering, provide antistatic effects. Polymethoxylsiloxanes modified with cationic and amphoteric groups provide both antistatic benefit as well as high gliding ability, which are very useful in personal care applications. ... 

Fraction C will contain the water-insoluble basic compoimds as well as amphoteric compounds alkalinization will precipitate the former but not the latter. From fraction D the insoluble acids may be removed by acidification. How will you test for the amphoteric group ... 

Phenolic groups, as in phloroglucinol residues introduced into chloromethylated polystyrene after the amination of half the chloro groups with trimethylamine to give 15, would be expected to be only about 3% ionised at pH 6. A polymer of this type is 80% as effective as a purely cationic one, but is four times more facile in regeneration. A further route to the desired charge reversal behavior is via the introduction of amphoteric groups into a cationic polymer as in 16. 

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