Polyester polyols of 2000 g mol⁻¹ M mass were synthesized via polyesterification reaction of butane‐1,4‐diol (1,4‐BDO) with linear dicarboxylic acids (DCAs) of odd and even carbon numbers, ranging from C₄ to C₁₀. Melt transition temperatures and crystallization enthalpies of polyester polyols demonstrated differing trends between odd and even chain lengths of their DCA monomeric units, with the latter possessing higher melt transition temperatures and melting enthalpies. The underlying cause of this difference may be attributable to the formation of a crystalline phase between the polyols' alkyl groups, which leads to proper alignment of ester bonds to allow for formation of dipoles that effectively cancel the local polarization. Thermoplastic urethanes (TPUs) were prepared by reacting the polyester polyols with 4,4′‐methylene bis(phenyl isocyanate) (4,4′‐MDI) and 1,4‐BDO chain extender at mole ratio of 1:2:1, respectively. Morphology, thermal and mechanical properties of TPUs were measured. Mechanical properties of TPUs also differ according to even vs. odd chain length of DCA monomeric units: higher hardness, tensile strength, hysteresis and tensile set for the former. The difference in properties is likely related to differences in phase segregation between hard and soft segments as a result of formation of hydrogen bonds as well as dipole–dipole interactions. Therefore, these findings have practical significance in the selection of polyester polyols to design TPUs for their specific applications.

中文翻译：

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聚酯多元醇二元羧酸单体链长对热塑性聚氨酯形态，热力学性能的影响

通过丁烷-1,4-二醇（1,4-BDO）与奇数和偶数碳数为C ₄至C的线性二羧酸（DCA）的聚酯化反应合成了2000 g mol ^-1 M质量的聚酯多元醇₁₀。聚酯多元醇的熔融转变温度和结晶焓显示出其DCA单体单元的奇数和偶数链长之间的趋势不同，后者的熔融转变温度和熔融焓更高。造成这种差异的根本原因可能是由于多元醇烷基之间形成了结晶相，这导致酯键正确对齐，从而形成了可有效抵消局部极化的偶极子。通过使聚酯多元醇与4,4'-亚甲基双（苯基异氰酸酯）（4,4'-MDI）和1,4-BDO扩链剂以1：2：1的摩尔比反应制备热塑性聚氨酯（TPU），分别。测量了TPU的形态，热和机械性能。TPU的机械性能也根据DCA单体单元的偶数链和奇数链长度而有所不同：前者的硬度，拉伸强度，滞后性和拉伸永久变形较高。由于形成氢键以及偶极-偶极相互作用，性质的差异可能与硬链段和软链段之间的相分离不同有关。因此，这些发现对于选择聚酯多元醇来设计用于其特定应用的TPU具有实际意义。