To improve the mechanical properties and structure of poly(vinyl chloride) (PVC)/nano-CaCO3 nanocomposite, a core (nano-CaCO3)/shell (SR) structured filler (40-60 nm) was successfully prepared by refluxing methyl vinyl silicone rubber (SR) and nano-CaCO3 particles (coupling agent KH550, KH560, or NDZ-101 as interfacial modifier) in toluene with vigorous stirring, according to an encapsulation model. It is effective in rigid PVC composite's toughness and reinforcement. The interfacial modifier's structure and interaction of nanocomposites of PVC/SR/nano-CaCO3 were studied. The results indicate that KH560 has the optimal interfacial modificatory effect. The environmental scanning electron microscope (ESEM) study testified that PVC/SR/nanoCaCO(3) nanocomposites had a typical rubber-plastics-toughening mechanism. (c) 2006 Wiley Periodicals, Inc.