Saha Joyanta K, Rahman Mohammad Mizanur, Haq Md Bashirul, Al Shehri Dhafer A, Jang Joonkyung
Department of Chemistry, Jagannath University, Dhaka 1100, Bangladesh.
Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
Polymers (Basel). 2022 Apr 21;14(9):1701. doi: 10.3390/polym14091701.
Hydrogen bonding in polyurethane (PU) is imposed by molecular parameters. In this study, the effect of structural isomerism of certain monomers on hydrogen bonding of waterborne polyurethane (WBPU) was studied theoretically and experimentally. Two dihydroxybenzene (DHB)-based structural isomers such as catechol (CC) and hydroquinone (HQ), with different OH positions on the inner benzene core, had been used. Two series of WBPU dispersions were prepared using CC and HQ with defined contents. The binding energies between the catechol (CC)/hydroquinone (HQ) (respective OH group) and urethane/urea were calculated theoretically. By using a density functional theory (DFT) method, it was found that the largest binding energy between the urea and CC was higher than that of urea and HQ. The FT-IR analysis of synthesized polymer was also carried out to compare the results with the theoretical values. The CC-based polymers showed a stronger hydrogen bond both theoretically and experimentally than those for HQ-based polymers. The higher level of hydrogen bond was reflected in their properties of CC-based polymers. The adhesive strength, thermal stability, and hydrophobicity were higher for CC-based materials than those for HQ-based materials. The adhesive strength was increased 25% with the addition of 2.0 wt% CC content. This adhesive strength slightly deviated at a moderately high temperature of 80 °C.
聚氨酯（PU）中的氢键由分子参数决定。在本研究中，从理论和实验两方面研究了某些单体的结构异构对水性聚氨酯（WBPU）氢键的影响。使用了两种基于二羟基苯（DHB）的结构异构体，如儿茶酚（CC）和对苯二酚（HQ），它们在苯环内核上的OH位置不同。使用具有特定含量的CC和HQ制备了两个系列的WBPU分散体。从理论上计算了儿茶酚（CC）/对苯二酚（HQ）（各自的OH基团）与聚氨酯/脲之间的结合能。通过密度泛函理论（DFT）方法发现，脲与CC之间的最大结合能高于脲与HQ之间的最大结合能。还对合成聚合物进行了傅里叶变换红外光谱（FT-IR）分析，以将结果与理论值进行比较。基于CC的聚合物在理论和实验上均显示出比基于HQ的聚合物更强的氢键。较高水平的氢键反映在基于CC的聚合物的性能上。基于CC的材料的粘合强度、热稳定性和疏水性均高于基于HQ的材料。添加2.0 wt%的CC含量时，粘合强度提高了25%。在80°C的中等高温下，这种粘合强度略有偏差。
