Sensitivity to the physical and chemical structure of hard‐segment‐reinforced polyurethane elastomers with variable percentage of hydrogen bonding

A series of segmented polyurethane elastomers was achieved with similar structures but with various percentages of hydrogen bonding. The effect of the hard segment (crystallizing or not) was followed by the inclusion of a conventional rigid diisocyanate, 4,4'-diphenyl methane diisocyanate, and an isocyanate with a large conformational mobility, 4,4'-dibenzyl diisocyanate. Hydrogen substitution was carried out with the following procedures: (1) the substitution of hydrogen bonding by direct exchange with deuterium of liquid D(2)O, (2) deuterafion by synthesis with deuterated chain extenders (CEs) or deuterated macrodiols (MDs), and (3) hydrogen substitution with inert -CH(3) groups. The stress-strain data and hysteresis in uniaxial tension indicated a dramatic softening and weakening when the hydrogen of the urethane groups was replaced by inert -CH(3) groups, which were incapable of undergoing intermolecular interactions. This was in contrast with the observations made on the materials synthesized with deuterated CEs, where the elastomeric behavior of the materials was observed to improve. For the materials obtained with deuterated MDs, significant modifications in the mechanical response were not observed relative to the analogous normal materials. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3544-3550, 2011