The properties and morphology of nano-calcium carbonate (nano-CaCO3) modified with the titanate coupling agent isopropyl trioleoyl titanate (IPTT) were characterized by Fourier transform infrared, thermogravimetric analyses, surface tension, and transmission electron microscopy. The results showed that the grafting ratio of IPTT on the surface of nano-CaCO3 (IPTT-Ca) increased with IPTT content. IPTT-Ca/PBA/PMMA (IPTT-Ca/ACR, PBA/PMMA core-shell polymer, referred to ACR) latexes were prepared by seeded emulsion polymerization. They were then used to mix with PVC resin. The outer layer (PMMA) enhanced the dispensability of IPTT-Ca/ACR in the PVC matrix by increasing the interfacial interaction of these composite particles with PVC. The notched impact strengths of the blends were influenced by the weight ratio of IPTT-Ca to BA/MMA monomers, the weight ratio of BA/MMA. The relationships between the mechanical properties and the core-shell composite structures were elaborated. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 1336-1346, 2010