合成半薩倫二苯基鋁錯合物與催化環酯類開環聚合;The synthesis of hemi-salen diphenyl aluminum complexes and catalysis of open ring polymerizations with lactones

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题名:	合成半薩倫二苯基鋁錯合物與催化環酯類開環聚合;The synthesis of hemi-salen diphenyl aluminum complexes and catalysis of open ring polymerizations with lactones
作者:	呂志軒;Lu, Chih-Hsuan
贡献者:	化學學系
关键词:	開環聚合;聚酯;polymerizations;polyester
日期:	2023-08-15
上传时间:	2024-09-19 14:48:49 (UTC+8)
出版者:	國立中央大學
摘要:	塑膠造成的汙染已成為嚴重的全球性問題。以生質原料合成出環酯類化合物，再經過開環聚合得到的聚酯，大多具有生物可降解性與生物相容性，能夠降低對非再生能源的依賴，可作為傳統塑膠的替代。本實驗合成一系列hemi-salen配位基，與三苯基鋁反應形成錯合物，再將這些錯合物應用於催化各式環酯類的開環聚合反應，以常見的ε-己內酯(ε-caprolactone, ε-CL)、乳酸交酯(L-lactide, L-LA)建立反應系統，深入探討反應動力學。根據實驗結果，此系列錯合物能夠廣泛催化不同的環酯化合物；立障較大的配位基能使錯合物具有較佳的催化活性。動力學實驗顯示，直接將催化劑、醇類起始劑、環酯類單體混合，為對單體的零級反應；若先將催化劑和起始劑混合，預活化後再加入單體，可以大幅提高反應速率，且轉變為對單體及對催化劑的一級反應，在常溫下CL ROP的kobs 與kp最佳為0.1626 min−1 以及9.5 L mol-1 min-1；而在L-LA ROP的活化能為17.0 kcal mol−1 。將聚合產物以GPC分析，發現零級反應產物的圖譜僅有一個波峰，而一級反應的產物則有兩個波峰，推論活化過的催化劑會形成新的活性物質，加速聚合反應。;Plastic pollution has become a serious global issue. Synthesizing cyclic ester compounds from biomass feedstocks and subsequently undergoing ring-opening polymerization to obtain polyesters can provide biodegradability and biocompatibility, reducing reliance on non-renewable resources and serving as alternatives to traditional plastics. In this experiment, a series of hemi-salen coordination ligands were synthesized and reacted with triphenylaluminum to form complexes. These complexes were then applied in catalyzing the ring-opening polymerization of various cyclic ester compounds, such as ε-caprolactone (ε-CL) and L-lactide (L -LA), to establish reaction systems and explore the reaction kinetics in depth. According to the experimental results, this series of complexes demonstrated broad catalytic activity towards different cyclic ester compounds, with larger ligands providing better catalytic activity. Kinetic experiments showed that directly mixing the catalyst, alcohol initiators, and cyclic ester monomers constituted a zero-order reaction with respect to the monomer. However, pre-activating the catalyst and initiators before adding the monomer significantly increased the reaction rate and transformed it into a first-order reaction with respect to both the monomer and the catalyst. For the CL ROP reaction at room temperature, the optimal kobs and kp were determined to be 0.1626 min−1 and 9.5 L mol−1 min−1, respectively. For the L -LA ROP reaction at higher temperatures, the activation energy was found to be 17.0 kcal mol−1. Gel permeation chromatography (GPC) analysis of the polymerization products revealed that the spectra of the zero-order reaction products exhibited a single peak, while the spectra of the first-order reaction products displayed two peaks. This suggests that the activated catalyst forms new active species, accelerating the polymerization reaction.
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