Syntheses and Characterizations of Soluble PDMS-Grafted Polyimides

Abstract

Polydimethylsiloxane (PDMS) grafted polyimides with different backbone structures were prepared by polycondensation of 3,5-bis(4-aminophenoxy)benzyloxypropyl-terminated PDMS with 4,4'-oxydiphtalic dianhydride (ODPA) and 4,4'-hexafluoroisopropylidene diphthalic anhydride (6FDA) followed by chemical imidization to afford PI-g-PDMS and FPI-g-PDMS, respectively. Another PDMS-grafted polyimide, MPI-g-PDMS, was also prepared by similar procedure from 3,5-bis(4-amino-3-methylphenoxy)benzyloxypropyl-terminated PDMS and ODPA.1 H-NMR and FT-IR spectra clearly demonstrated that the desired PDMS-grafted polyimides were successfully synthesized. FPI-g-PDMS and MPI-g-PDMS exhibited the high solubility, which were soluble in chloroform, THF, DMF, NMP, toluene, benzene as well as acetone, while PI-g-PDMS was soluble only in chloroform. Therefore, the membranes could be prepared by solvent-casting method using chloroform. Interestingly, the obtained membranes became insoluble in any solvents after the thermal imidization at 200℃ in vacuo for 24 h.