Meng Zihao, Wang Ying, Luo Yanlong, Luo Zhenyang, Li Linling, Sha Ye
Department of Chemistry and Material Science, College of Science, Nanjing Forestry University, Nanjing 210037, China.
Institute of Critical Materials for Integrated Circuits, Shenzhen Polytechnic University, Shenzhen, Guangdong 518055, China.
Langmuir. 2024 Sep 10;40(36):19220-19227. doi: 10.1021/acs.langmuir.4c02411. Epub 2024 Aug 27.
Using a "core-first" approach with atom transfer radical polymerization, fluorescent center-functional star polymers of equivalent molecular weight but with varying numbers of arms (di-, tri-, and tetra-arm) were prepared. The sensitivity of fluorescence, combined with a dye-labeling technique introducing a fluorescent donor (carbazole) and an acceptor (anthracene) at the center of poly(methyl methacrylate) (PMMA) chains, enabled the application of time-resolved fluorescence resonance energy transfer to obtain quantitative insights into the conformation of the star polymer chains in the film state. When the results of star-branched polymers were compared with those of linear polymers of identical type and molecular weight, the impact of branching on polymer behavior was isolated for examination. Although the star topology does not alter the average intercoil distance, it affects the distance dispersity. Star polymers with higher arm numbers display decreased dispersity from distance due to reduced intermolecular aggregation at their geometric centers. This study presents the first spectroscopic evidence regarding the distribution of geometric centers in star polymers, offering a physical understanding of chain interpenetration and entanglement within star polymers.
采用“先核后臂”的原子转移自由基聚合法，制备了具有相同分子量但臂数不同（二臂、三臂和四臂）的荧光中心功能化星形聚合物。荧光的敏感性，结合在聚甲基丙烯酸甲酯（PMMA）链中心引入荧光供体（咔唑）和受体（蒽）的染料标记技术，使得时间分辨荧光共振能量转移得以应用，从而定量了解薄膜状态下星形聚合物链的构象。当将星形支化聚合物的结果与相同类型和分子量的线性聚合物的结果进行比较时，就可以单独研究支化对聚合物行为的影响。尽管星形拓扑结构不会改变平均线团间距离，但它会影响距离分散性。臂数较多的星形聚合物由于其几何中心处分子间聚集减少，距离分散性降低。这项研究提供了关于星形聚合物中几何中心分布的首个光谱证据，有助于从物理角度理解星形聚合物内的链相互渗透和缠结。
