The effect of annealing on latex film surface structure was followed b
y atomic force microscopy. The films were prepared from poly(butyl met
hacrylate) particles (PBMA, d = 337 nm) prepared by surfactant-free em
ulsion polymerization. The film surfaces were highly ordered, consiste
nt with face-centered cubic packing in the film interior, and each par
ticle maintained a truncated spherical shape. The peak-to-valley dista
nce DELTAz was monitored as a function of annealing time. From DELTAz,
the remaining surface per particle was calculated. With the aid of a
simple diffusion model, we conclude from these data that polymer chain
s near the latex surface diffuse much faster than those within the fil
m.