RAFT dispersion polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) is performed in n-dodecane at 90 °C using a relatively short poly(stearyl methacrylate) (PSMA) precursor and 2-cyano-2-propyl dithiobenzoate (CPDB). The growing insoluble poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA) block results in the formation of PSMA–PTFEMA diblock copolymer nano-objects via polymerization-induced self-assembly (PISA). GPC analysis indicated narrow molecular weight distributions (M_w/M_n ≤ 1.34) for all copolymers, with ¹⁹F NMR studies indicating high TFEMA conversions (≥95%) for all syntheses. A pseudo-phase diagram was constructed to enable reproducible targeting of pure spheres, worms, or vesicles by varying the target degree of polymerization of the PTFEMA block at 15–25% w/w solids. Nano-objects were characterized using dynamic light scattering, transmission electron microscopy, and small-angle X-ray scattering. Importantly, the near-identical refractive indices for PTFEMA (1.418) and n-dodecane (1.421) enable the first example of highly transparent vesicles to be prepared. The turbidity of such dispersions was examined between 20 and 90 °C. The highest transmittance (97% at 600 nm) was observed for PSMA₉–PTFEMA₂₉₄ vesicles (237 ± 24 nm diameter; prepared at 25% w/w solids) in n-dodecane at 20 °C. Interestingly, targeting the same diblock composition in n-hexadecane produced a vesicle dispersion with minimal turbidity at a synthesis temperature of 90 °C. This solvent enabled in situ visible absorption spectra to be recorded during the synthesis of PSMA₁₆–PTFEMA₈₆ spheres at 15% w/w solids, which allowed the relatively weak n→π* band at 515 nm assigned to the dithiobenzoate chain-ends to be monitored. Unfortunately, the premature loss of this RAFT chain-end occurred during the RAFT dispersion polymerization of TFEMA at 90 °C, so meaningful kinetic data could not be obtained. Furthermore, the dithiobenzoate chain-ends exhibited a λ_max shift of 8 nm relative to that of the dithiobenzoate-capped PSMA₉ precursor. This solvatochromatic effect suggests that the problem of thermally labile dithiobenzoate chain-ends cannot be addressed by performing the TFEMA polymerization at lower temperatures.

中文翻译：

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通过RAFT分散甲基丙烯酸2,2,2-三氟乙基酯在正构烷烃中的聚合制备高度透明的二嵌段共聚物囊泡

甲基丙烯酸2,2,2-三氟乙基酯（TFEMA）的RAFT分散聚合反应是在90°C的正十二烷中使用较短的聚甲基丙烯酸硬脂酯（PSMA）前体和2-氰基-2-丙基二硫代苯甲酸酯（CPDB）进行的。不断增长的不溶性聚（2,2,2-三氟乙基甲基丙烯酸甲酯）（PTFEMA）嵌段通过聚合诱导自组装（PISA）导致形成PSMA–PTFEMA二嵌段共聚物纳米物体。GPC分析表明窄分子量分布（中号_瓦特/中号_Ñ ≤1.34）的所有共聚物，用¹⁹F NMR研究表明，所有合成均具有较高的TFEMA转化率（≥95％）。伪相图可以通过改变PTFEMA嵌段在15–25％w / w固含量下的目标聚合度来实现可重现的纯球体，蠕虫或囊泡靶向。使用动态光散射，透射电子显微镜和小角X射线散射对纳米物体进行表征。重要的是，PTFEMA（1.418）和正十二烷（1.421）的折射率几乎相同，因此可以制备高度透明的囊泡的第一个示例。在20至90℃之间检查了这种分散体的浊度。对于PSMA ₉ –PTFEMA ₂₉₄，观察到最高透射率（在600 nm处为97％）于20°C的正十二烷中的小泡（直径237±24 nm；固体含量为25％w / w制备）。有趣的是，在90°C的合成温度下，以正十六烷中相同的二嵌段组成为目标，可制得具有最小浊度的囊泡分散液。这种溶剂可以在固含量为15％w / w的PSMA ₁₆ –PTFEMA ₈₆球体合成过程中记录原位可见光吸收光谱，从而允许在515 nm处将相对弱的n→π*谱带分配给二硫代苯甲酸酯链端。被监视。不幸的是，在90°C下TFEMA的RAFT分散聚合过程中，发生了该RAFT链端的过早丢失，因此无法获得有意义的动力学数据。此外，二硫代苯甲酸酯的链端表现出λ相对于二硫代苯甲酸酯封端的PSMA ₉前体的_最大位移为8 nm 。这种溶剂化显色效应表明，通过在较低温度下进行TFEMA聚合无法解决热不稳定的二硫代苯甲酸酯链端问题。