利用聚碳酸酯回收中間體合成可再加工熱固性聚氨酯

Abstract

石油開採的蓬勃發展，對於合成高分子材料的研究推波助瀾，高分子已經成為日常不可或缺的材料，產品應用範圍廣泛，與人類生活的關係更加密切。然而，多數人工合成的高分子在大自然中因為其穩定的分子結構而難以分解，造成廢棄物回收與環境的問題，漸漸成為環保議題的一大隱患。為了提升材料利用的永續性，綠色化學逐漸受到重視，因此如何開發出對環境友善能自然分解的高分子材料，或發展出屬於高分子的材料循環利用模式，使高分子對環境的傷害降到最低，甚至達到無汙染的目標，讓科技的發展與環境保護之間能相互並進，是高分子領域的科學家共同的使命。 因此，本研究中，針對擁有廢棄物議題之工程塑料-聚碳酸酯(PC)，將其作為原料利用雙胺進行胺解，使聚碳酸酯轉換為反應中間體，透過簡單的一鍋二步法，將PC轉化為回收的聚氨酯(PU) ，將其製備成具有優秀機械性質的回收熱固性聚氨酯材料。同時，透過導入觸媒動態鍵結機制，讓其成為具有可逆動態交聯結構，並藉由回收製程的調整，使其動態可逆性大幅增加。實驗過程中，使用雙胺將聚碳酸酯PC分解為胺基甲酸酯反應中間體 (DP-biscarbamates, DP-C)，可以免去複雜的純化步驟，無高溫高壓，將其製備成具優秀機械性質之回收熱固性聚氨酯材料，並透過傅立葉轉換紅外光譜儀 (FT-IR)搭配核磁共振(NMR)進行結構鑑定，同時測定熱性質與機械性質，還有最重要的回復性測試，來了解材料是否有循環利用的潛力。論文中亦使用了核磁共振(NMR)及質譜儀（MS）探討交聯熱固性聚胺酯之動態可逆反應機制。回復性測試結果顯示，熱固性聚胺酯經過三次熱壓回收的PU 樣品，仍能維持原先(14.94 MPa, 3115%)之56%的應力強度以及60%延展性(8.49 MPa, 1890%)。運用新回收方法，不僅能夠以高效率將聚碳酸酯進行回收，並進一步藉由添加催化劑的方法，使熱固性材料具有動態可逆共價鍵，成功賦予其回收再塑形的能力。

With the development of science and technology, polymers have become indispensable materials in daily life. However, polymers are not easy to recycle and easily cause environmental pollution. Therefore, the significance of green chemistry has gradually received attention in the development of recent years. In this study, using a new recycling method to not only makes polycarbonate into versatile intermediates efficiently, but also synthesize a thermosetting polyurethane material with excellent mechanical properties. The success of the useful method was based on an efficient aminolysis process via amine carbonylation reaction in the absence of catalysts under mild conditions. Meanwhile, the dynamic reversible covalent bond is introduced into the thermosetting materials, which gives it the ability of reshaping and repeated recycling. The process was based on a model study between various biscarbamate compounds to come up with a suitable dynamic reversible condition as our reprocessing basis. With the NMR and MS result, the condition for the dynamic network featuring for urethane reversion could be achieved. Consequently, through the crosslinking process physically and chemically, the thermosetting PUs have the possibility of recycling over and over aganin by introducing covalent adaptable networks. Consequently, these polymer network were cracked into pieces and compress-molded into the original shape again. Most importantly, researching on its dynamic reversibility mechanism and the possibility of reprocessing. As a result, this polymer networks possessed covalent adaptably networks.