Macrocrystal swelling: AFM in situ observation of particle and film deformation and motion

The surface of a poly(styrene-hydroxyethylmethacrylate), macrocrystalline f ilm was observed by atomic force microscopy in the contact mode, before and during film immersion in water. The swelling effect on film morphology is strongly dependent on the quality of the macrocrystalline surface: film int egrity is preserved or concerted many-particle displacement is observed in well-organized areas with few defects, but extensive particle displacement is observed in highly defective areas. The lateral particle dimensions incr ease by ca. 10-15% only and particle aspect ratio is unaltered in the highl y crystalline areas. However, him roughness is greatly decreased, and hat m irror-like surface domains are obtained due to the concerted effects of par ticle swelling and latex-water interfacial tension. (C) 2001 Academic Press .