高頻低介電生質聚對苯二甲酸丁二酯與深共熔溶劑輔助二醇解聚回收製程開發

Abstract

近年來，因應石化資源有限與環保需求日益迫切，由生質來源合成之高分子材料逐漸受到學術界與產業界的高度關注。其中，聚酯材料因其優異的機械性質、熱穩定性與耐化學性，已被廣泛應用於電子、包裝與塑膠等領域。因此，開發具高生質含量之聚酯材料，並建立相應的回收與再利用策略，已成為兼具應用潛力與永續發展的重要研究方向。本論文擬引入源自植物油之脂肪族二聚體二醇與1,4-丁二醇作為生質單體，期望合成兼具高生質含量與良好性能之聚酯材料，並推動其於軟性電子領域中的應用，後續亦將探討新穎之聚酯二醇解聚途徑，以深入評估其應用可行性。 本研究第二章透過單體結構設計，開發具高生質含量與低介電特性的熱塑性共聚酯，並系統性探討生質二醇單體（二聚體二醇、1,4-丁二醇）與芳香族二酯單體（對苯二甲酸二甲酯、間苯二甲酸二甲酯、萘二甲酸二甲酯）對材料機械與介電性質之影響。結果顯示，共聚間苯二甲酸二甲酯可增加自由體積，顯著提升材料柔韌性，其斷裂延伸率由109%提升至607%，惟介電常數與損耗因子略有上升；而共聚剛性較高之萘二甲酸二甲酯則有助提升機械強度並抑制介電性質，其在29 GHz下的介電常數由2.43降至2.32。上述結果為柔性電子材料設計與生質聚酯開發提供重要參考。而本研究第三章引入近年興起之新型環保溶劑──深共熔溶劑，應用於聚對苯二甲酸丁二酯之二醇解聚製程，並首度嘗試以金屬鹽與反應溶劑直接組成深共熔溶劑，兼具溶劑與催化劑功能，無需額外添加成分。本研究成功合成並定義由氯化鋅與丁二醇構成之深共熔溶劑，並與氯化鋅/乙二醇系統一同進行解聚探討。結果顯示，兩類系統皆可有效促進聚對苯二甲酸丁二酯之二醇解聚，其中以氯化鋅/乙二醇系統在200 °C、莫耳比1:8至1:100條件下表現最佳，轉化率達88–100%，雙（2-羥乙基）對苯二甲酸酯產率最高達57%。本章結果不僅驗證金屬鹽與溶劑可直接構成深共熔溶劑的可行性，也展現其於聚酯解聚中兼具溶劑與催化劑之應用潛力。 綜合第二與第三章之研究，分別從高生質共聚酯的材料設計與廢棄物回收兩個面向進行探討，若進一步將回收所得的雙（2-羥乙基）對苯二甲酸酯與雙（2-羥丁基）對苯二甲酸酯單體可以和二聚體二醇再共聚回O1或O2，可實現閉環完整循環體系，建立一套具體可行的生質高分子功能化開發與再利用策略，未來可應用於低碳排放與高附加價值的永續材料產業。

In recent years, the scarcity of petrochemical resources and growing environmental concerns have brought increasing attention to bio-based polymeric materials from both academia and industry. Among them, polyesters are widely used in electronics, packaging, and plastics because of their outstanding mechanical characteristics, thermal stability, and chemical resistance. Developing polyesters with high bio-based content, along with effective recycling and reuse strategies, has thus become a key research direction with strong application potential and sustainability value. This study employs aliphatic dimer diol (DDO) derived from plant oils and 1,4-butanediol (BDO) as bio-based monomers to synthesize polyesters with both high bio-based content and desirable performance, aiming at applications in flexible electronics. In addition, novel glycolysis routes for polyester depolymerization are explored to evaluate their practical feasibility. In Chapter 2, bio-based thermoplastic copolyesters with low dielectric properties were developed through monomer structure design. The effects of bio-based diols (DDO and BDO) and aromatic diesters (dimethyl terephthalate (DMT), dimethyl isophthalate (DMI), and dimethyl naphthalenedicarboxylate (NDC)) on the mechanical and dielectric properties were systematically examined. Results showed that copolymerizing DMI increased free volume and significantly enhanced flexibility, with elongation at break rising from 109% to 607%, though with a slight increase in dielectric constant and loss factor. In contrast, incorporating the more rigid NDC improved mechanical strength and reduced dielectric properties, lowering the dielectric constant from 2.43 to 2.32 at 29 GHz. These findings provide valuable insights for designing flexible electronic materials and developing bio-based polyesters. Chapter 3 introduces deep eutectic solvents (DESs), a new class of green solvents, into the glycolysis of poly(butylene terephthalate) (PBT). This study is the first to directly combine metal salts and reaction solvents to form DESs that function simultaneously as solvent and catalyst, without the need for additional components. A DES composed of ZnCl2 and BDO was successfully synthesized and evaluated alongside a ZnCl2/EG system. Both systems effectively promoted the glycolysis of PBT, with the ZnCl2/EG system showing the best performance at 200 °C and a molar ratio of 1:8 to 1:100, achieving a conversion rate of 88–100% and a bis(2-hydroxyethyl) terephthalate (BHET) yield of up to 57%. These results confirm the feasibility of directly forming DESs from metal salts and solvents and demonstrate their dual function in polyester depolymerization. Integrating the results of Chapters 2 and 3, this study addresses both the design of high bio-based copolyesters and polymer waste recycling. The recovered monomers—BHET and BHBT—can be repolymerized with DDO to regenerate O1 or O2, forming a complete closed-loop system. This establishes a practical strategy for the functional development and reuse of bio-based polymers, with potential applications in low-carbon, high-value sustainable materials.