Hole formation and size evolution on the surface of thin films of symmetric diblock copolymers is simultaneously investigated as a function of time, t, temperature, T, and film thickness, h. The hole size h approaches a steady state value at long times where this limiting value increases as the temperature increases. A model of the hole growth kinetics is introduced to describe these observations. The time constant characterizing the rate of approach of h to its asymptotic value first decreases and then increases with increasing T. These observations suggest a reduction of the surface elasticity of the outer block copolymer layer with increasing temperature and a critical slowing down of the film equilibration to its steady state. These effects are tentatively interpreted to arise from thermal fluctuations associated with the disordering transition.
Pub Type: Journals
block copolymers, critical fluctuation effects on dynamics, defects, hole formation, kinetics, order-disorder transition, surface pattern formation