The conformational studies of polymers confined at the nanoscale remain challenging and controversial due to the limitations of characterization techniques. In this study, we utilized the high sensitivity of time-resolved fluorescence resonance energy transfer (trFRET) and a site-specific dye-labeling strategy to characterize the conformation of polymer chains confined in anodic aluminum oxide (AAO) nanopores. This strategy introduced a fluorescent donor (carbazole) and acceptor (anthracene) at the center of poly(butyl methacrylate) (PBMA) chains grown by atom transfer radical polymerization (ATRP). By quantitatively analyzing fluorescence decay through the Förster mechanism and the Drake–Klafter–Levitz (DKL) formalism, we can determine both the energy transfer efficiency and the spatial distribution of the dyes. This analysis revealed that the PBMA chains, with a molecular weight of 40 kDa, maintained their bulk-like conformation even when confined within nanopores as small as 10 nm in diameter. This study is the first to demonstrate the use of trFRET for investigating chain conformation in confined polymer systems, which can be generalized to other polymer types and polymer topologies in different confined geometries.

中文翻译：

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通过时间分辨荧光共振能量转移对限制在纳米孔中的聚合物链构象的定量检查和机理见解


由于表征技术的局限性，受限于纳米尺度的聚合物的构象研究仍然具有挑战性和争议。在这项研究中，我们利用时间分辨荧光共振能量转移 （trFRET） 的高灵敏度和位点特异性染料标记策略来表征局限在阳极氧化铝 （AAO） 纳米孔中的聚合物链的构象。该策略在原子转移自由基聚合 （ATRP） 生长的聚甲基丙烯酸丁酯 （PBMA） 链的中心引入了荧光供体 （咔唑） 和受体 （蒽）。通过通过 Förster 机制和 Drake-Klafter-Levitz （DKL） 形式定量分析荧光衰变，我们可以确定染料的能量传递效率和空间分布。该分析表明，分子量为 40 kDa 的 PBMA 链即使局限在直径小至 10 nm 的纳米孔内，也能保持其块状构象。这项研究首次证明了使用 trFRET 研究受限聚合物系统中的链构象，这可以推广到不同受限几何形状中的其他聚合物类型和聚合物拓扑结构。