Advanced Textile Technology

   

Influence mechanism of microphase structure on the strength and toughness properties of multi-block reactive polyurethane materials

  

  • Published:2025-05-19

"多嵌段反应性聚氨酯材料的微相结构 对其强韧性能的影响机制"

  

Abstract: "With the advancement of the ""dual carbon"" goals (carbon peaking and carbon neutrality), environmental friendliness has emerged as one of the pivotal directions in the development of materials science. Reactive polyurethane (RPU) has garnered widespread application in fields such as high-performance coatings, elastomers, and synthetic leathers, owing to its excellent weather resistance, chemical stability, and mechanical properties achieved through a highly cross-linked molecular structure under solvent-free conditions. Compared with traditional solvent-based and waterborne polyurethane systems, RPU demonstrates significant advantages in reducing volatile organic compound (VOC) emissions and improving production efficiency. However, the mechanical properties of polyurethanes often face a trade-off between strength and toughness: an increase in strength typically leads to a decline in toughness, thereby elevating the risk of brittle fracture. This issue becomes particularly pronounced under solvent-free synthesis routes, where the lack of solvent's fluidity and processing convenience exacerbates the challenge. This paper proposed an innovative approach: in a solvent-free system, a rigid-flexible integrated silicone polyurethane (Six-RPU) system was constructed through a two-component in situ polymerization strategy. Polydimethylsiloxane (PDMS), polytetramethylene ether glycol (PTMEG), and castor oil (CO) were selected as the soft segments, while hexamethylene diisocyanate (HMDI), binaphthol (BIONL), and 1,4-butanediol (1,4-BDO) were chosen as the hard segments. This strategy aims to synthesize Six-RPU materials that possess both high rigidity and high toughness. Contact angle measurements revealed that with the introduction of 15% PDMS into the polyurethane main chain, the hydrophilicity of Six-RPU underwent a significant transformation to hydrophobicity, with the hydrophobicity angle reaching 117.3°. Furthermore, the Si-O layer formed during the thermal degradation of PDMS significantly increased the high-temperature char yield of RPU, as confirmed by TGA tests. The rigid network formed between the flexible Si-O-Si soft segments provided by PDMS and the binaphthyl hard segments constructed a robust and complementary structure, successfully achieving outstanding mechanical properties that harmonized rigidity and flexibility. Mechanical tensile test results indicated that, compared to Si0%-RPU, the tensile strength of Si15%-RPU increased from 26.6 MPa to 30.8 MPa, the elongation at break rose from 550.4% to 704.1%, and the toughness escalated from 56.3 MJ/m3 to 138.8 MJ/m3. Through characterization analyses such as AFM, XRD, and DSC, the formation mechanism of the rigid-flexible structure and microstructure were further elucidated: PDMS disrupted the ordered stacking of hard segments through multiple hydrogen bonding interactions with the hard segments and its inherent incompatibility with them, thereby promoting ordered microphase separation and the formation of a more stable two-phase structure. This, in turn, optimized the mechanical properties and microstructure of the polyurethane."

Key words: multi-block, reactive polyurethane, microphase separation, strength and toughness

摘要: 为了解决反应性聚氨酯(RPU)高强度与高韧性之间的矛盾,在无溶剂体系中,以聚二甲基硅氧烷(PDMS)、聚四氢呋喃醚二醇(PTMEG)和蓖麻油(CO)为软段,二环己基甲烷二异氰酸酯(HMDI)、联萘酚(BIONL)和1,4-丁二醇(1,4-BDO)为硬段,通过双组分原位聚合构筑了刚柔结构单元互补的有机硅RPU。系统分析了BIONL@PDMS对RPU微观结构、疏水性、热性能及力学性能的影响。结果表明:当质量分数为15%的PDMS引入RPU主链后,Six-RPU展现出优异的疏水性,接触角达到117.3°。此外,PDMS还可促进Si−O炭层形成,提升RPU的残炭量。PDMS的柔性Si−O−Si软段与联萘硬段之间的刚性网络共建了强韧的互补结构,显著增强了其力学性能。与Si0%-RPU相比,Si15%-RPU的拉伸强度提高至30.8 MPa,断裂伸长率达到704.1%,韧性增至138.8 MJ/m3,显示出优异的力学性能。研究结果可为高性能聚合物材料的设计提供新思路。

关键词: 多嵌段, 反应性聚氨酯, 微相分离, 强韧性

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