具有多个侧链 2-ureido-4[1H]-pyrimidone 单元的线性聚氨酯中氢键组装的特性和机理,Journal of Applied Polymer Science

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具有多个侧链 2-ureido-4[1H]-pyrimidone 单元的线性聚氨酯中氢键组装的特性和机理
Journal of Applied Polymer Science ( IF 2.7 ) Pub Date : 2022-12-19 , DOI: 10.1002/app.53520
Yimei Chen _{1,

2} , Wei Yang _{1,

2} , Juan Liu _{1,

2} , Yuanliang Wang _{1,

2} , Yanfeng Luo _{1,

2}

Affiliation

2-Ureido-4[1 H ]-pyrimidone (UPy) 可形成强四重氢键（H 键），广泛用于构建超分子。尽管含 UPy 聚合物的氢键组装已被广泛报道，但很少有人关注含 UPy 聚氨酯的氢键特性和机理。在这里，通过使用具有多个 UPy 侧链单元的线性聚氨酯 UPy- p -PDLLA-SMPU 作为模型聚合物，系统地研究了溶液、固体膜和熔体中的氢键组装特性。发现UPy单元在DMSO中主要以游离单体形式存在，在CHCl _{3中以UPy二聚体形式存在}, 以及 DMF 中的游离单体和二聚体。UPy的二聚化可以促进脲基和氨基甲酸酯基团的氢键结合，从而形成硬链段聚集体。因此，UPy- p -PDLLA-SMPU 薄膜和熔体中 H 键的耐热性和可逆性均显着增强。UPy- p -PDLLA-SMPU 可以从橡胶态 (70°C–85°C) 转变为粘流态 (≥120°C)，呈现化学交联和线性聚氨酯的特性。这项工作清晰地展示了 UPy 单元与 UPy- p中的尿素和氨基甲酸酯基团的氢键组装-PDLLA-SMPU。获得的组装特性和机理有利于UPy基物理交联聚氨酯的设计和加工。

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The characteristics and mechanism of hydrogen bonding assembly in linear polyurethane with multiple pendant 2-ureido-4[1H]-pyrimidone units

2-Ureido-4[1H]-pyrimidone (UPy) can form strong quadruple hydrogen bonding (H-bonding) and is widely used to construct supramolecules. Though the H-bonding assembly of UPy-containing polymers has been widely reported, little attention is paid to the H-bonding characteristics and mechanism of UPy-containing polyurethanes. Here, by using UPy-p-PDLLA-SMPU, a linear polyurethane with multiple pendant UPy units as the model polymer, the H-bonding assembly characteristics in solution, solid film and melt are systematically investigated. It is found that the UPy units mainly exist as free monomers in DMSO, UPy dimers in CHCl₃, and both free monomers and dimers in DMF. The dimerization of UPy can promote the H-bonding of urea and urethane groups and thus the formation of hard segment aggregates. Thereby, the thermal resistance and reversibility of the H-bonds are significantly enhanced in both UPy-p-PDLLA-SMPU film and melt. UPy-p-PDLLA-SMPU can transition from a rubber state (70°C–85°C) to a viscous flow state (≥120°C), presenting the characteristics of both chemically crosslinked and linear polyurethanes. This work provides a clear picture on the H-bonding assembly of UPy units together with urea and urethane groups in UPy-p-PDLLA-SMPU. The obtained assembly characteristics and mechanism are beneficial for the design and processing of UPy-based physically crosslinked polyurethanes.

更新日期：2022-12-19

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