In Situ Atomic Force Microscopy Tracking of Nanoparticle Migration in Semicrystalline Polymers

We present in situ tracking of silica nanoparticle (NP) migration from a poly(ethylene oxide) (PEO) melt into interlamellar region using in situ atomic force microscopy (AFM). Our results confirm the previous hypothesis that NPs migrate into the interlamellar regions at crystallization growth rates smaller than a critical value under isothermal conditions. Under these slow crystallization conditions, bare silica NPs are rejected as defects by the growing crystal of PEO, and the in situ imaging on the large (50 nm) NPs helps track the migration into the amorphous zones. We extend this AFM technique to estimate lamellar growth rates that correlate with spherulite growth rates determined by polarized light optical microscopy (PLOM) but at smaller undercoolings than are typical for PLOM.