High-performance recyclable cross-linked polyurethane with orthogonal dynamic bonds: The molecular design, microstructures, and macroscopic properties
High-performance recyclable cross-linked polyurethane with orthogonal dynamic bonds: The molecular design, microstructures, and macroscopic properties
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具有正交动态键的高性能可回收交联聚氨酯：分子设计、微观结构和宏观性能
DOI：
10.1016/j.polymer.2018.06.024
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发表时间：
2018-07-18
期刊：
影响因子：
4.6
通讯作者：
Sun, Pingchuan
中科院分区：
文献类型：
--
作者：
Li, Mei;Zhang, Rongchun;Sun, Pingchuan
聚氨酯材料因其化学性质的多样性而广泛应用于工业和日常生活中。然而，尽管合成化学的快速发展，它仍然是一个重大的挑战，易于制造的PU与嵌入具有优异的机械性能和可回收性的单一交联网络。因此，在本研究中，我们提出了一种简单的策略来制备高性能的可回收交联聚氨酯，并揭示了微观结构和宏观性能之间的关系。将UPy（2-脲基-4-[1H]-嘧啶二酮）基序引入PU的主链中，其中UPy二聚体之间的四重氢键相互作用可以显著提高机械强度和韧性。此外，使用单个小分子Diels-Alder加合物作为化学交联剂，使得最终交联的PU可愈合和可回收。DSC和固体核磁共振谱很好地验证了Diels-Alder反应的热可逆性。值得注意的是，发现UPy基序的掺入可以增强应变诱导结晶（SIC），导致大的断裂应力。通过质子多量子NMR光谱和SAXS实验定量地研究了SIC引起的结构和动力学变化，其中SIC进一步限制了软域中周围聚合物链的流动性，并导致微相分离纳米结构的变化。总体而言，这里提出了一个简单的策略，为高性能可回收PU的简易制造，和详细的调查，这里的结构-性能的关系，可以进一步提供见解，开发高性能的聚合物材料。(c)2018爱思唯尔有限公司版权所有
Polyurethane materials (PUs) have been widely used in industry and daily life due to the versatile chemistry. However, despite the rapid advance in synthetic chemistry, it still remains a significant challenge for the facile fabrication of PUs with a single cross-linked network embedded with excellent mechanical properties and recyclability. Herein, in this study, we proposed a simple strategy to fabricate a high-performance recyclable cross-linked PU and revealed the relationship between microscopic structure and macroscopic properties. The UPy (2-ureido-4-[lH]-pyrimidione) motifs were incorporated into the backbone chains of PUs, where the quadruple hydrogen bonding interactions between UPy dimers can significantly enhance the mechanical strength and toughness. Furthermore, a single small molecular Diels-Alder adduct was utilized as the chemical crosslinker, rendering the final cross-linked PUs healable and recyclable. The thermal reversibility of the Diels-Alder reaction was well verified by DSC and solid-state NMR spectroscopy. Notably, it was found that the incorporation of UPy motifs could enhance the strain-induced crystallization (SIC), leading to a large stress at break. The structural and dynamic changes induced by SIC were quantitatively addressed by proton multiple-quantum NMR spectroscopy and SAXS experiments, where SIC further imposed restrictions on the mobility of surrounding polymer chains in the soft domain and led to the change of microphase separated nanostructures. Overall, a simple strategy is proposed here for the facile fabrication of high performance recyclable PUs, and the detailed investigation here on the structure-property relationship may further provide insights into developing high performance polymeric materials. (c) 2018 Elsevier Ltd. All rights reserved.