Monolayer of amphiphilic functionalized gold nanoparticles at an air-water interface.
Langmuir films at the air-water interface exhibit a variety of surface phases which arise primarily due to the molecular interaction governed by intermolecular separation. We have studied the thermodynamical aspects of Langmuir monolayers of amphiphilic functionalized gold nanoparticles (AGNs) at the air-water (A-W) interface. Interestingly, the AGN monolayer exhibits phases like gas, a low-ordered liquid (L1) , a high-ordered liquid (L2) , and a collapsed state. We find that the first-order phase transition between L1 and L2 vanishes above a critical temperature of 28.4 degrees C . Surprisingly, for a range of higher temperatures ( > or = 29.4 degrees C and < or = 36.3 degrees C ), the L1 phase undergoes a transition to a bilayer of the L2 phase before entering into the collapsed state.
Birla Institute of Technology and Science, Pilani, Physics Group, Rajasthan 333031, India. raj@bits-pilani.ac.in
Raj Kumar
RK
Gupta
K A
KA
Suresh
Sandeep
S
Kumar