INVESTIGATION AND GAS-PERMEABILITY OF POLYURETHANE COMPLEXES

Ionic polyurethane (PU) membranes of hydroxyl-terminated polybutadiene (HTPB) and 4,4'-dicyclohexylmethane diisocyanate (H12MDI) were polyme rized by a two-stage method. The ionic group was introduced by adding N-methyldiethanolamine (MDEA) as the chain extender of which the terti ary amines were complexed with cobalt ions. It was found that the bind ing of hard segments and the flexibility of soft segments had subtle e ffects on the gas permeability. The effects of hard segment content an d the amount of cobalt ion on the gas permeability and morphological p roperties were investigated. Fourier transform infrared (FTIR) spectro scopy was utilized to identify the segregation between hard and soft s egments and structure change, which affect the transport properties. T he hydrogen bonding index (HBI), frequency difference, and shift as a measure of the phase segregation and the average strength of the inter polymer hydrogen bonds were utilized to study the intermolecular inter action and transport property of the prepared PUs. The results of diff erential scanning calorimetry, thermogravimetric analysis (TGA), and F TIR measurements explain the complexation and, hence, the gas permeabi lity. (C) 1998 John Wiley & Sons, Inc.