A Comparison of Hydrogen Bonding and Order in a Polyurethane and Poly(urethane−urea) and Their Blends with Poly(ethylene glycol)

Abstract

The effect of hydrogen bonding on the phase behavior of a chemically similar polyurethane and polyurea and their blends with poly(ethylene glycol) is examined. The polyurethane and polyurea were synthesized from the same diisocyanate, 1,5-diisocyanato-2-methylpentane, using an aromatic diol and aromatic diamine, respectively. Fourier transform infrared spectroscopy was used to characterize the distribution of hydrogen bonds in these polymers and their blends. The distribution of hydrogen bonds in the polyurethane homopolymer was found to be quite similar to that found in an amorphous polyurethane studied previously in this laboratory. However, upon annealing, some sort of ordered structure was detected spectroscopically. The polyurea formed an equivalent ordered structure much more readily at room temperature. Ordered hydrogen-bonded domains were also detected in the spectra of the blends, either after an extended time at room temperature or after annealing at an elevated temperature. The formation of ordered structures occurred at temperatures well below the thermally measured glass transition. Melting endotherms could not be detected in most of these samples. It is suggested that the order present in these blends might be largely two-dimensional. The hydrogen bonds between adjacent urethane (or urea) units can align to form a sheet, with the methyl group that is part of each segment essentially laying in a plane that is perpendicular to this structure. Because the methyl group is asymmetrically placed in the diisocyanate used to synthesize these polymers, packing between sheets would be imperfect at best.

Novel phenyl‐POSS/polyurethane aqueous dispersions and their hybrid coatings

“…PU12 had the highest T d among all these hybrids. The T d of the hybrids increased slightly, with a maximum increase of about 22 C from 285 to 307 C with the increasing POSS content from 0 to 12 wt %. The characteristic temperatures of PU0, PU4, PU8, and PU12 for the 50% weight loss were 393, 415, 422, and 424 C, respectively (Table V).…”

“…22 The peak at 1530 cm 21 is assigned to the NAH bending vibration present in the PU samples, and the bands at $1240 cm 21 can be collectively attributed to the ester CAOAC asymmetric stretching vibration. 23 The wide AA-POSS peak between 1078 and 1145 cm 21 is ascribed to SiAO stretching vibrations.…”

Effect of Backing Films on the Transdermal Delivery of Donepezil from Patches

“…However, this exceptional phenomenon was not contradictive to the above-mentioned redshift criterion. Since, the C=O acceptor groups and N-H donor groups in polyurethane can form intermolecular hydrogen bond (13,14), while the H bond acceptors in DP might disrupt the original intermolecular hydrogen bond by forming new hydrogen bond with N-H donor groups in polyurethane. According to literatures (15), it could be concluded that all H bond acceptors in DP had weaker electronegativity than the C=O H bond acceptor in polyurethane, thus inducing the electron rearrangement of H atom in the N-H group and the blueshift of the N-H group stretching absorption (16).…”

Synthesis and Characterization of New Polyurea Elastomers by Sol/Gel Chemistry

“…[13,14] Generally, the reaction for obtaining linear polymers (thermoplastic block copolymers) takes place between a diisocyanate (aromatic or aliphatic) with an aminoterminated prepolymer or resin (generally aliphatic). [8,10,[14][15][16][17][18][19][20][21][22][23] The prepolymer or resins contains both soft segments with low glass transition temperatures and amorphous melts, and hard domains with high glass transition and high melting temperatures due to hydrogen bonding [24,25] as physical crosslinks. Little work has been done for the synthesis and study of polymer networks because of the fast reactivity during chemical crosslinking, except by using spray or reaction injection molding.…”