A series of novel organotin containing core cross linked knedels and shell cross linked knedels were first synthe sized facilely from poly(styrene) b-poly(acrylate acid) nanopar tides in different selective solvents [Tetrahydrofuran (THF)/H2O or THF/n octane] by using organotin compound 1 3 dichloro tetra n butyl distannoxane as a new cross linker The formation of the 1 chloro 3 carboxylato tetra n butyl distannoxane layer in our cross linking reaction was supported by Fourier trans form infrared (FT IR) and inductive coupled plasma emission spectrometer (ICP) analysis of the resulting shell cross linked knedels and core cross linked knedels Transmission electron microscopy (TEM) study showed the spherical morphology and the size of the core cross linked knedels and shell cross linked knedel Especially the layer structure of the core cross linked knedels was clearly displayed in TEM image The increase of extent of cross linking lead to the increasing of di ameter for the shell cross linked knedels whereas there was no significant effect on the core cross linked knedels Dynamic light scattering (DLS) measurements gave hydrodynamic diam eters of the core cross linked knedels that were in agreement with the TEM diameters Moreover the wall thickness of the shell layer of the core cross linked knedels could be easily modified by varying the block copolymer composition Nota bly the organotin containing core cross linked knedel exhibited highly efficient catalytic activity for the aqueous esterificiation reaction under nearly neutral conditions (C) 2010 Wiley Periodi cals Inc J Polym Sci Part A Polym Chem 48 5992-6002 2010