永續生質複合材料於高效能包裝之應用

Abstract

傳統石化塑膠長期主導包裝材料市場，主要歸因於其低成本、易於大規模製造能力以及良好的加工性。然而，這些材料往往因缺乏經濟誘因而難以回收，在廢棄處理過程中還會造成嚴重且長期的環境污染，例如塑膠微粒的釋放與高碳排放。隨著全球永續發展與循環經濟理念的推動，石化塑膠正逐漸受到來自社會與產業的挑戰與質疑。因此，如何尋找兼具性能與永續性的替代方案，成為材料科學與綠色製造領域亟需解決的課題。 本論文以「永續生質高分子取代石化塑膠包裝材料」為核心理念，選擇纖維素與木質素兩種自然界中含量豐富、容易取得、可再生且尚未被充分利用的生質資源作為材料設計基石。透過由上而下(top-down)與由下而上(bottom-up)的雙重策略，建構出兼顧結構強度、阻隔性能與多重複合功能的材料發展平台。整體規劃涵蓋三個研究主題，分別從宏觀結構、介觀組裝到分子設計三個層面，逐層展現核心概念的技術可行性與價值。 在宏觀層級(macroscopic system)，研究一著重於木材資源的再利用。雖然傳統發泡聚苯乙烯(EPS)材料良好的絕熱性質，但在耐溶劑、阻燃性及永續性方面表現不足。本研究利用回收木材(RW)為基材，透過氣相反應形成多孔的纖維素骨架，再填充二氧化矽氣凝膠(silica aerogel)製備木材複合材料(SAWc)。經結構導入後，SAWc同時展現低熱傳導率、高抗壓強度、優異耐溶劑性與耐燃性，能應用於冷鏈運輸、保溫建材及高值化綠色包裝材料，為傳統發泡塑膠提供低碳且具生物降解性的替代方案，凸顯宏觀結構設計在循環經濟中的潛在貢獻。 在介觀層級(mesoscopic system)，研究二以細菌纖維素(BC)為主要基材。BC具有高結晶度與奈米纖維網絡結構，能提供優異的機械強度與氣體阻隔性，然而原生BC膜在耐水性與光學透光性上仍有不足。為克服此挑戰，本研究引入水性聚氨酯(WPU)與海藻酸鈉(SA)作為輔助相，並透過金屬離子(Zr4+)螯合進一步提升結構緊密性。所得到的BC/WPU/SA@Zr-0.10多層薄膜兼具高透明度、耐水性與優異氧氣阻隔性。同時由於完全採用天然高分子，更能夠符合可降解與環境友善的需求。此成果驗證了介觀層次的多相組裝策略能有效將生質高分子轉化為具競爭力的綠色功能薄膜。 在分子設計(molecular design)層級，研究三則聚焦於木質素的高值化利用。木質素因富含芳香族結構而具備天然剛性與本質阻燃性，然而其高度複雜且不均一的化學結構限制了其規模化的工業應用。本研究透過化學改質將木質磺酸鹽(lignosulfonate)修飾為可反應的環氧基體，並進一步製備成類玻璃態高分子(vitrimer)。藉由引入動態共價鍵 (DCBs)，賦予該材料可回收性、自我修復與熱觸發再加工特性。在最佳化配方下，木質素基可以取代80%傳統雙酚A二縮水甘油醚(DGEBA)，且該木質素基vitrimer同時展現高玻璃轉換溫度(Tg)、良好機械強度與優異阻燃性，不僅可應用於結構黏著劑或玻纖複合材料基體，也突顯木質素作為功能性高分子的潛力，突破其過往僅作為燃料或低值填料的侷限。 綜合三個研究案例，本論文建構出一套跨尺度的永續材料發展藍圖：宏觀層級的木材複合材料，提供隔熱與阻燃解決方案；介觀層級的BC多層膜，展現高透明與阻隔性能，適用於綠色食品包裝；分子設計層級的木質素vitrimer，則帶來可回收、再加工與黏著功能。纖維素提供穩固結構與阻隔效能，木質素則賦予高性能與動態可設計性。兩者互補，不僅展現其取代石化塑膠的可行性，更拓展功能材料的應用場域及產品化的可能性。相關成果可望推廣至冷鏈物流、食品安全包裝、可回收黏著劑與綠色建材等產業。此研究強調唯有從結構、功能與循環全方位思考，才能建立真正的綠色材料的典範轉移(paradigm shift)，為全球減碳與資源再利用目標貢獻實質力量。

Conventional petrochemical plastics have long dominated the packaging industry, primarily due to their low cost, scalability in mass production, and excellent processability. However, these materials are difficult to recycle because of limited economic incentives, and their disposal generates severe and long-lasting environmental issues, including microplastic release and high carbon emissions. With the global advancement of sustainability and circular economy concepts, petrochemical plastics are increasingly subject to societal scrutiny and industrial challenges. Consequently, the urgent task for materials science and green manufacturing is to identify alternatives that balance high performance with sustainability. This dissertation embraces the central concept of “sustainable bio-polymers as substitutes for petrochemical plastics in packaging applications” by selecting cellulose and lignin as the foundational resources. These natural polymers are abundant, renewable, easily accessible, and remain underutilized. By integrating top-down and bottom-up design strategies, this work establishes a multiscale materials platform that simultaneously addresses structural robustness, barrier performance, and multifunctionality. The overall framework encompasses three research themes, investigated across the macroscopic, mesoscopic, and molecular levels, thereby validating the technical feasibility and intrinsic value of this approach. At the macroscopic level, the first study focuses on the reutilization of wood resources. While conventional expanded polystyrene (EPS) exhibits favorable thermal insulation, it lacks solvent resistance, flame retardancy, and sustainability. In this work, recycled wood (RW) serves as the base material, which is modified through vapor-phase processing to form a porous cellulose scaffold subsequently impregnated with silica aerogel, yielding a silica aerogel-wood composite (SAWc). This engineered composite exhibits low thermal conductivity, high compressive strength, and superior resistance to solvents and flames. These properties position SAWc as a low-carbon and biodegradable alternative to traditional foamed plastics, with potential applications in cold-chain transport, thermal insulation in construction, and high-value green packaging. This outcome underscores the role of macroscopic structural design in advancing the circular economy. At the mesoscopic scale, the second study utilizes bacterial cellulose (BC) as the major substrate. BC has high crystallinity and nanoscale fibrous network structures that are endowed with superior mechanical toughness as well as excellent gas barrier capability. In spite of that, pure BC films are handicapped by poor water resistance as well as optical non-transparency. In an endeavor for mitigation, waterborne polyurethane (WPU) as well as sodium alginate (SA) served as working phases, with the addition of zirconium ion (Zr4+) chelating functioning to advance structural density further. Obtained BC/WPU/SA@Zr-0.10 multilayer film possesses high visibility, impressive water resistance, with remarkable barrier performance. In addition, consisting solely of natural polymers, it completely corresponds with biodegradability as well as environmental compatibility specifications. This paper substantiates that mesoscopic multiphase assembling chemistry strategies could efficiently convert bio-polymers into competitive functional green films. At the molecular design level, the third study valorization of lignin. Largely due to its rigid-construct aromatic skeleton, lignin intrinsically possesses stiffness as well as flame retardancy, but its highly complexed heterogenic-chemical constitution has limited bulk quantities large-scale deployments. In the current study, lignosulfonate was chemically converted to an accessible reactive epoxy precursor, subsequently compounded to a vitrimer network. Insertion of dynamic covalent bonds (DCBs) grants recyclability, self-healing, with heat-triggered reprocessability. With optimized formulation settings, lignin-centered vitrimers successfully substitute up to 80% contents for the traditional diglycidyl ether of bisphenol A (DGEBA), retaining high glass transition temperature (Tg), high mechanical property, with high flame retardancy. With these materials possessing the possibility for structural adhesive or matrix application in the situation for the glass fiber reinforcement matrix formats, lignin indicates its potential for becoming a useful high-performance polymer with its historical contemplative reservations for becoming simply combustion material or filler. In summary, the three researches create multiscale roadmaps for sustainable material construction: macroscopic silica aerogel-wood hybrids providing thermal insulation and flame retardancy; mesoscopic BC multilayered sheets providing optical transparency and barrier property for sustainable food packaging; and molecular-level lignin vitrimers providing recyclability, reprocessability, and adhesive properties. Cellulose provides structural reinforcement and barrier property, while lignin provides high-performance functionality and dynamic tunability. Correlative findings will also be put to use on the cold-chain logistics, multi-function food package, reusable adhesive, and green construction material. In the current research, this dissertation has also indicated that the paradigm shift for the green material will only become reality by adopting an ecosystem perspective on structural performance, performance, and lifecycle circularities. Through doing so, the current research will fulfill the carbon mitigation and resource reusing goals for the entire planet.