透過動態共價鍵實現可重組之量子點-類玻璃高分子複合材料

Abstract

量子點(quantum dots; QDs)因其優異之光學特性而備受關注，然而應用於顯示器時須仰賴熱固性高分子(thermoset polymer)載體以提供支撐與穩定性，CdSe系列量子點雖發展技術最為成熟，然而其含重金屬鎘元素，對環境與回收利用構成挑戰，為解決此問題，本研究開發一種具可回收特性之複合材料，將CdSe@CdZnSeS/ZnS量子點以一鍋法均勻摻入聚酯型類玻璃高分子(polyester-based vitrimer; PEV)中，製成QD@PEV複合放光材料，其中PEV含動態共價鍵(dynamic covalent bond)之特性，使其兼具熱固性材料之機械穩定性與熱塑性材料(thermoplastic polymer)之可重塑特性，藉由鋅離子催化醇解(alcoholysis)反應，可於中性條件下實現量子點與高分子基材之分離與再利用，接著離心(centrifuge)、蒸餾(distillation)與混入量子點再製，建立閉環回收製程(closed-loop system)，回收量子點(recycled-QD; r-QD)維持其晶體結構與光學表現，回收PEV (recycled-PEV; r-PEV)經感應耦合電漿光學發射光譜儀(inductively coupled plasma optical emission spectroscopy; ICP-OES)與同步輻射X光吸收邊緣結構(X-ray absorption near-edge structure; XANES)分析確認幾乎無鎘離子殘留。此外，掃描穿透式電子顯微鏡(scanning transmission electron microscope; STEM)與同步輻射穿透式小角度X光散射(transmission small angle X-ray scattering; TSAXS)分析顯示量子點於PEV中之分散性優於傳統熱固性高分子光固膠，最後將QD@PEV光學膜應用於量子點背光液晶顯示器(quantum-dot liquid crystal display; QD-LCD)裝置中，於國際照明委員會(Commission Internationale de l'éclairage; CIE) 1931色彩座標下接近白光色點(0.28,0.32)，並實現99.9% sRGB與99.7% DCI-P3之色域覆蓋率。本研究提出一種兼具光學性能與永續回收潛力之綠色材料設計策略，為奈米材料之環保應用提供新方向。

Quantum dots (QDs) have attracted significant attention due to their excellent optical properties. However, their application in display devices often requires thermoset polymer matrices to provide mechanical support and structural stability. CdSe-based QDs, which represent the most technically mature class of quantum dots, pose environmental and recyclability challenges due to their heavy metal cadmium content. To address this issue, this study developed a recyclable composite material by uniformly incorporating green and red CdSe@CdZnSeS/ZnS QDs into a polyester-based vitrimer (PEV) via a one-pot synthesis to prepare QD@PEV luminescent composites. The PEV matrix features dynamic covalent bonds, providing the material with the mechanical robustness of thermoset polymers and the reprocessability of thermoplastics. Through a zinc-catalyzed alcoholysis reaction, QDs and the polymer matrix can be effectively separated and reused under neutral conditions. Following centrifugation, distillation, and reintegration of QDs, a closed-loop recycling system was established. The recycled-PEV (r-QDs) retained their crystal structure and optical performance, while the recycled-PEV (r-PEV) showed negligible cadmium residue based on inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray absorption near-edge structure (XANES) analysis. Furthermore, scanning transmission electron microscopy (STEM) and transmission small-angle X-ray scattering (TSAXS) confirmed the superior dispersibility of QDs within the PEV matrix compared to conventional thermoset UV glue polymers. Finally, the QD@PEV optical film was applied in a quantum-dot liquid-crystal display (QD-LCD) device, achieving a nearly white emission point at (0.28, 0.32) in the Commission Internationale de l'éclairage (CIE) 1931 chromaticity diagram, with 99.9% sRGB and 99.7% DCI-P3 color gamut coverage. This study presents a green materials design strategy that combines excellent optical performance with sustainable recyclability, offering a new direction for the eco-friendly application of nanomaterials.