Soluble poly(imide-siloxane)s were obtained by carefully designing the synthesis and introducing poly(ethylene glycol) (PEG) units, thereby making the system amphiphilic in nature. The solubility of the synthesized PEG containing poly (mide-siloxane)s (PPIS) in various solvents was tested and their thermal properties were investigated. Polymeric siloxane networks were prepared by combining imide groups and hydrophilic PEG components with sufficient variability in their composition to analyze their physicochemical details. The amine groups of the imides were varied in their rigidity and bulkiness, and their effect on the mechanical and thermal properties was studied. Here we have also examined the surface property of the networks through contact angle measurements, morphology through SEM, existence of amorphous nature by WAXD, and their structure-property relationships were correlated. The thermal analysis revealed the phase separation of the three components poly(dimethyl siloxane) (PDMS), PEG, and imide, showing a tricomponent amphiphilic conetworks. The mechanical properties were found to be improved by the phase separated PPIS containing more rigid imide groups. The overall properties of the amphiphilic conetwork has the features of differing hydrophilicity, mobility, and morphology distributed across a matrix, which has a microphase separated design suitable for gas separation and biomedical applications. (c) 2007 Wiley Periodicals, Inc.