Theoretical study of hydrogen bonding interactions on MDI-based polyurethane
Theoretical study of hydrogen bonding interactions on MDI-based polyurethane
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DOI：
10.1007/s00894-010-0645-4
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发表时间：
2010-08-01
影响因子：
2.2
通讯作者：
Ji, Fenglong
中科院分区：
文献类型：
--
作者：
Zhang, Cuili;Hu, Jinlian;Ji, Fenglong
采用密度泛函理论（DFT）研究了4，4'-二苯基甲烷二异氰酸酯（MDI）聚氨酯硬段和软硬段之间的氢键作用。B3LYP/6 - 31 G * 和B3PW91/6 - 31 G * 方法都给出了较好的结构、合理的Mulliken电荷、结合能、偶极矩和较好的红外光谱趋势。键距R（N-H. O），羰基键合的氢键在3.005 - 3.028埃范围内，酯键合的氢键在3.074 - 3.075埃范围内，与实验值基本一致。聚氨酯中大部分羰基氧以氢键形式存在。具有两个羰基氢键的配合物（c）具有最大的偶极矩，而具有两个酯氢键的配合物（d）具有最小的偶极矩，即，低于孤立的单体，这可能是由于两个单体的对称性。这些结果证实了密度泛函方法是研究弱相互作用的一个很好的工具，并表明羰基和N-H或酯和N-H之间确实形成了氢键，前者更强。
Hydrogen bonding among hard hard segments and hard soft segments in 4,4'-diphenylmethane diisocyanate (MDI)-based polyurethane was investigated theoretically by density functional theory (DFT). Both B3LYP/6-31G* and B3PW91/6-31G* methods gave good structures, reasonable Mulliken charges, binding energies, dipole moments, and good infrared (IR) spectra trends in predicting hydrogen bonding. Bond distances R(N-H ... O), which were in the range of 3.005-3.028 angstrom for the carbonyl bonded hydrogen-bond, and 3.074-3.075 angstrom for the ester bonded hydrogen-bond, are in reasonable agreement with experimental values. Most of the carbonyl oxygen in polyurethane exists in a hydrogen-bonded form. Complex (c), with two carbonyl hydrogen bonds, features the largest dipole moment, while complex (d) with two ester hydrogen bonds, possesses the smallest dipole moment, i.e., lower than that of the isolated monomer, which may be due to the symmetry of the two monomers. These results confirm that the DFT method is a good tool with which to study weak interactions, and indicate that hydrogen bonds are indeed formed between carbonyl and N-H, or ester and N-H, with the former being stronger.