ATR-FTIR is used to investigate the hydrogen-bonding properties of urethane/urea polymers with two soft segments, poly(propylene oxide) and polybutadiene. The polymers are prepared by extending a poly(propylene oxide)-based triisocyanate-terminated prepolymer (PU) with poly(butadienediol) (PBDO). The C=O and N-H stretching bands in the spectra of the polymers are deconvoluted into five components, which are ascribed to different free and hydrogen-bonded groups. Results gave evidence of hydrogen bonding between hard/hard segments, leading to the formation of aggregates of urethane/urea groups. This aggregation changed upon variation of the proportion of the two soft segments in the membranes. The increase of PBDO content in the membranes leads to an improvement of the mixing of the two soft segments and also the decrease of the urethane/urea aggregation.