Transformation of PEI to the Polymer Having Water-Crosslinkable Function Using Silane Couplers Having Isothiocyanato Group

For the transformation of PEI into a water-crosslinkable polymer, the reactivity of PEI with silane couplers having a isothiocyanato group 3-alkoxysilylpropyl isothiocyanate (ASPI), especially 3- (diethoxymethylsilyl) propyl isothiocyanate (1a), preparation of their adduct polymer (PEIASP), and its water-crosslinking ability were examined. The reaction of PEI with ASPI proceeded at a similar rate to that of the model reaction, and a the adduct polymer PEIASP. The percent introduction of the ASP unit into PEI chain increased with the molar ratio of 1a to PEI toward saturation at ca. 70%. The PEIASP became soluble in non-polar solvents in addition to polar ones, and the film-forming property was improved with increasing ASP unit. The water-crosslinkability of PEIASP was clarified from the gelation of their alcoholic solutions by the addition of water, and insolubilization of their cast films or viscous liquid films by the steam-exposure.