Narrow Results

In the present communication, the monolayer characteristics of pyrene mixed with stearic acid (SA) at the air–water interface have been reported. The monolayer properties are investigated by recording and analyzing the surface pressure–area per molecule isotherm (π–A) of the pyrene–SA mixed films. It is observed that the pyrene and SA are miscible in the mixed monolayer. This miscibility/nonideality leads to phase separation between the constituent components (pyrene and SA). BAM image of the mixed monolayer confirms the miscibility or nonideal mixing at the mixed monolayer.

The amphiphilic TEMPO molecules consist of two dissimilar parts. One part is hydrophilic (head) and the rest part is hydrophobic (tail). The derivatives of 4-alkaneamino-2, 2, 6, 6-tetramethyl-1-piperidinyloxy radical (C_n-amino-TEMPO, n = 14, 16, 18, 20, 22) was synthesized with 4-amino-TEMPO and carboxylic acid. The C_n-amino-TEMPOs equilibrated at the air/water interface form Langmuir monolayer by classical Langmuir monolayer techniques. The stable monolayers of C_14-22-amino-TEMPOs were characterized by pressure–area isotherms. The features of collapse pressure of C_14-22-amino-TEMPOs were confirmed on alkyl chain length. Limiting area points and take-off area points from surface pressure-MMA isotherms were subjected to the influence of subphase. The monolayer of C₂₂-amino-TEMPO which has longer alkyl chain was characterized by Brewster Angle Microscopy. So we can confirm phase transition by BAM images as monolayer is expanding at the room temperature.