AFM of poly(vinyl alcohol) crystals next to an inorganic surface

Crystallization of poly(vinyl alcohol) in the presence of an inorganic fill er surface (sodium montmorillonite, MMT) was observed and compared to the c rystallization of the neat polymer. For this purpose, several atomic force microscopy modes, providing spatial resolution between amorphous and crysta lline polymer, are employed to observe filled and unfilled PVA films. The v arious AFM modes utilized are detailed, with the emphasis on how they can c ontrast stiff (crystalline) and softer (amorphous) domains on a polymer sur face. The study revealed changes in the PVA crystal morphology, with bulk c rystallites growing to sizes of more than 5 mum, whereas next to the inorga nic surfaces grow to only 1-2 mum in size. Moreover, complementary X-ray di ffraction and DSC investigations indicate a new crystal structure formed ne xt to the MMT surfaces, at the expense of the bulklike crystal.