Surface Chemistry of Unexposed and Exposed Powders

0 surfactant. Unamine 0 is a 1-hydroxy-ethyl 2-heptadecenyl 2-imidazoline which consists of a five member heterocyclic ring with an alcohol at the one position and an aliphatic chain at the two position as depicted in the reaction below  

In acidic aqueous solutions at room temperature, the imidazoline has not been observed to undergo hydrolytic ring fissure The imidazoline ring is extremely reactive in the presence of water in non-aqueous and aqueous solutions that are neutral or basic. The imidazoline undergoes a base-catalyzed hydrolisis ring opening resulting in an amide reaction product (Reaction 

The surface chemistry of the SioN surfaces and their interactions with TM 

The hydroxylatlon of the sllazane surface species to a level of 1.5 wtZ, results In a calculated SI2-NH site density of 4 s1tes/nm. Beyond 1.5 wtX, a slower weight gain regime results. This Is attributed to physically (or hydrogen bonded) adsorbed water. The amount of physically axlsorbed water Is seen to be proportional to the relative humidity. 

The Karl Fisher measurements of the heated evacuated powder yield a total water content of 3.73 wt%, while an exposed powder has a total water concentration of 5.72 wt%. Titration measurements indicate that the physi sorbed water content of the heated evacuated powder is 1.73 wt%. Thus, the remaining 2.00 wtX corresponds to the concentration of Si-OH sites. This is considered to be in good agreement with the weight gain data (described above). 

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