Poly(tetram ethylene ether) glycol containing acetal linkages: New PTMG-based polyol for chemically recyclable polyurethane thermoplastic elastomer
Poly(tetram ethylene ether) glycol containing acetal linkages: New PTMG-based polyol for chemically recyclable polyurethane thermoplastic elastomer
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DOI：
10.1002/pola.22501
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发表时间：
2008-03-01
影响因子：
--
通讯作者：
Urushisaki, Michio
中科院分区：
文献类型：
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作者：
Hashimoto, Tamotsu;Mori, Hiroaki;Urushisaki, Michio
在聚氨酯材料的回收方法中，化学回收是一种很有前途的方法，通过这种方法，聚氨酯可以转化回多元醇等起始材料。1适用于聚氨酯化学回收的工艺包括水解、氨解、醇解、糖酵解等。1，2然而，由于氨基甲酸酯键固有的化学稳定性，这些工艺通常需要苛刻的反应条件，如高温（> 200 ℃），因此涉及复杂的降解化学，以产生许多降解产物的混合物。1，2本研究涉及一种新型的可化学回收的聚氨酯弹性体的开发，该弹性体可以在室温下清洁地降解以再生高纯度的多元醇。最终的关键是在聚合物的设计阶段将合适的可降解官能团引入聚合物的概念。为此，使用缩醛嵌入的多元醇作为原料将缩醛基团引入聚氨酯主链中。方案1说明了本研究中制备的聚氨酯弹性体的合成路线和结构，其中使用聚（四亚甲基醚）二醇（PTMG），因为这是热塑性聚氨酯弹性体的代表性多元醇。3、PTMG与4-乙酰氧基丁基乙烯基醚（AcBVE）的加成反应生成了酯封端的缩醛连接的PTMG（PTMG-Acetal-OCOCH 3），PTMG-Acetal-OCOCH 3的酯端基经碱水解生成了相应的羟基封端的缩醛连接的PTMG（PTMG-Acetal-OH）。以4，40-二苯基甲烷二异氰酸酯（MDI）为二异氰酸酯，1，4-丁二醇（BD）为扩链剂，合成了主链含缩醛键的PTMG基聚氨酯（PTMG-Acetal-PU）。本文报道了PTMG-缩醛-OH和PTMG-缩醛-PU的合成，并与传统的无缩醛键的PTMG基聚氨酯（PTMG-PU）的热性能和力学性能进行了比较。还建立了PTMG-缩醛-PU的酸诱导降解过程以再生用于化学回收的PTMG（方案2）。
Among recycling methods of polyurethane materials, chemical recycling is a promising means by which the polyurethanes can be converted back to starting materials like polyols. 1 The processes applicable to chemical recycling of polyurethanes include hydrolysis, aminolysis, alcoholysis, glycolysis, etc. 1, 2 Because of inherent chemical stability of urethane linkages, however, such processes usually require severe reaction conditions like high temperature (> $200 8C) and hence involve complicated chemistry of degradation to give a mixture of a number of the degradation products. 1, 2 The present study concerns the development of a type of new chemically recyclable polyurethane elastomers, which can be cleanly degraded at room temperature to regenerate polyols in high purity. The key to the end is the concept that suitable degradable functional groups are incorporated into the polymers in their design stage. For this, acetal groups were introduced into polyurethane backbones using acetal-embedded polyols as a raw material. Scheme 1 illustrates the synthetic route and structure of the polyurethane elastomer prepared in this study, where poly (tetramethylene ether) glycol (PTMG) was employed because this is a representative polyol for thermoplastic polyurethane elastomers. 3 The addition reaction of PTMG with 4-acetoxybutyl vinyl ether (AcBVE) gave an ester-capped, via acetal connections, PTMG (PTMG-Acetal-OCOCH3), and the subsequent alkaline hydrolysis of the ester terminal groups of PTMG-Acetal-OCOCH3 produced the corresponding hydroxy-capped PTMG with acetal linkages (PTMG-Acetal-OH). The PTMG-Acetal-OH was then utilized for usual polyurethane synthesis involving the reactions with 4, 40-diphenylmethane diisocyanate (MDI) as a diisocyanate and 1, 4-butanediol (BD) as a chain extender to give the PTMG-based polyurethane with acetal linkages in the main chain (PTMG-Acetal-PU). In this article, we report the synthesis of the PTMG-Acetal-OH and PTMG-Acetal-PU, and compare the thermal and mechanical properties of PTMG-Acetal-PU with those of the conventional PTMG-based polyurethane without acetal linkages (PTMG-PU). Acid-induced degradation process of PTMG-Acetal-PU to regenerate PTMG for chemical recycling was also established (Scheme 2).