Model butanediol–MDI–polypropylene oxide polymers have been synthesized to explore the structure–property relationships in urethane/polyether polymers. The results of mechanical, thermal, and spectroscopic analyses agree remarkably well. The phase mixing in these polymers decreases with increasing hard‐segment length, while the hard‐segment stability increases with increasing hard‐segment length. This is demonstrated clearly by dynamic mechanical, differential scanning calorimetry, infrared, and NMR studies. The importance of hydrogen bonding to the stability of the hard segment is strongly supported by the variable‐temperature infrared experiments. The critical hard‐segment size for phase segregation was shown to be two butanediols per hard segment. The temperature limit of the flatness of the storage modulus was tied to the thermal stability of the hard‐segment hydrogen bonding which is controlled largely by the length of the hard segment and the extent of the hydrogen bonding.

We describe a new modeling approach to prediction of Young's modulus of segmented polyurethanes. This approach combines micromechanical models with thermodynamic considerations based on the theory of block copolymers. The resulting model predicts both the equilibrium morphology and the ''ideal'' Young's modulus of a segmented polyurethane polymer as a function of its formulation (hard segment chemical structure, hard segment weight fraction, soft segment equivalent weight) and temperature.

Eight infants with histories of apnea and cyanosis were referred to the Southwest SIDS Research Institute for evaluation of apparent life threatening events (ALTE). All of the infants had been treated for colic with a 1:1 concentration of dimenhydrinate (Dramamine) and phenobarbital, hyoscyamine sulfate, atropine sulfate and scopolamine hydrobromide (Donnatal). The medication was pre-mixed by local pharmacists. A comprehensive work-up failed to reveal a cause for the ALTE in any infant. The Dramamine/Donnatal mixture was withdrawn and polygraphic evaluation was conducted. Cardiorespiratory abnormalities were identified in all eight infants and significant gastroesophageal reflux (GER) was documented in four. The possibility that colic medication contributes to cardiorespiratory instability and GER in vulnerable infants requires serious consideration and further evaluation.

Model urethane elastomers consisting of 4,4'-methylene diisocyanate, l,Cbutanediol, and a 2000 molecular weight poly(oxypropylenedio1) were examined by solid-state carbon-13 NMR spectroscopy. T, values were determined for the aromatic and butanediol carbons as a function of cross polarization fiefd strength and temperature. The results for the aromatic carbons correlate well with observed hightemperature behavior of the elastomer as determined by dynamic mechanical spectroscopy. The biexponential decay of the butanediol resonances indicated that two types of motional populations can be associated with the phase-segregated portion of the hard segment. These results demonstrate the intimate connection between molecular motion and mechanical properties in urethane polymers. This understanding provides an important framework for optimizing physical properties in urethane polymers.