Friedel–Crafts alkylation was employed for the preparation of benzyl chlorine-free branched poly(4-acetoxystyrene) (PSTO). Firstly, the cationic polymerization of 4-acetoxystyrene (STO) was conducted in CH₂Cl₂ at − 15 °C with 1-phenylethyl chloride (St–Cl)/SnCl₄/nBu₄NBr initiating system. Then, the chlorine end-groups would further slowly undergo alkylation reactions (mainly intra-molecular) at 0 or − 15 °C. The Friedel–Crafts alkylation can be accelerated by elevating the reaction temperature to 25 °C, which finally led to a complete conversion of terminal benzyl chlorine groups. ¹H NMR and Triple-detection GPC equipped with multi-angle laser light scattering detector (MALLS), a viscosity detector (VIS), and a refractive index detector (RI) revealed the occurrence of inter-molecular alkylation at 25 °C, which resulted in the formation of branch topology. Because of the advantages of chlorine-free and branched structures, the product is expected to be applied as photoresists to meet the requirements for high pattern resolution requirement.

Graphical abstract

The benzyl chlorine-free branched poly(4-acetoxystyrene) (PSTO) was synthesized after full monomer consumption at higher temperature through Friedel–Crafts alkylation between living chain ends and benzene rings of the PSTO backbones.

中文翻译：

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通过活性聚合和傅克烷基化合成支化和无苄基氯的聚（4-乙酰氧基苯乙烯）

Friedel-Crafts 烷基化用于制备无苄基氯的支化聚（4-乙酰氧基苯乙烯）（PSTO）。首先，4-乙酰氧基苯乙烯 (STO) 的阳离子聚合在 CH ₂ Cl ₂中在 - 15 °C 下使用 1-苯乙基氯 (St-Cl)/SnCl ₄ /nBu _​​4 NBr 引发体系进行。然后，氯端基将在 0 或 - 15 °C 下进一步缓慢地进行烷基化反应（主要是分子内）。将反应温度提高到 25 °C 可以加速 Friedel-Crafts 烷基化反应，最终导致末端苄基氯基团的完全转化。¹H NMR 和配备多角度激光散射检测器 (MALLS)、粘度检测器 (VIS) 和折光率检测器 (RI) 的三检测器 GPC 揭示了在 25 °C 发生分子间烷基化，导致形成分支拓扑。由于无氯和支化结构的优点，该产品有望用作光刻胶，以满足高图案分辨率的要求。

图形概要

无苄基氯的支化聚（4-乙酰氧基苯乙烯）（PSTO）是在较高温度下通过活性链末端和 PSTO 主链的苯环之间的傅克烷基化反应合成单体。