TEM Investigation and Electron Diffraction Study on Dispersion of Gold Nanoparticles into a Nylon 11 Thin Film during Heat Treatment.

We have investigated the effect of heat treatment on the changes in the microstructure of nylon 11 thin films containing nanosized Au particles by means of lateral and cross-sectional transmission electron microscopy. It was observed that, on heat treatment, the Au islandlike particles initially deposited on the nylon 11 surface penetrated into the polymer layer to form a composite film consisting of nanosized spherical Au particles dispersed in a polymer matrix, while the initially amorphous nylon 11 matrix crystallized to the alpha-crystalline form. The surface stress coefficient of the Au particles, calculated from the lattice constant determined by the electron diffraction patterns, decreased as the Au particles penetrated into the polymer matrix, which can be due to both coalescence of the particles to a spherical shape and reduction of the surface free energy of the particles by embedding in the matrix. The molecular chain motion of the nylon 11 matrix during the crystallization process is suggested to be responsible for the dispersion of Au particles into the polymer matrix. Copyright 1999 Academic Press.