Here, 0.5vol% of PMMA-grafted gold nanoparticles* are dispersed into a solution of PMMA:SAN (50:50) in MIBK, followed by spin-coating to make homogeneous composite film with a thickness of ~120nm. Fig (a) shows homogeneous depth distribution of gold particles with some substrate segregation, due to the preannealing process used to remove the solvent (120°C, 24hr). After annealing at high temperature (200°C, 5hr), preferential wetting of PMMA at the surface and substrate caused redistribution of gold particles along with the PMMA phase, leading to a pseudo-trilayer formation in Fig (b). Glancing angle technique (75° tilt of sample goniometer) was used to improve depth resolution.

Submitted by Hyun-joong Chung, Department of Materials Science and Engineering

* PMMA-grafted gold nanoparticles (~2.7nm, MPMMA=27[Kda]) were kindly provided by Dr. Kohji Ohno in Kyoto University.