Poly(p-phenylene vinylene)s (PPVs) are some of the most widely studied conjugated polymers in academia and industry, but most production methods lack precise control over molar masses and alkene stereochemistry. These critical parameters have a large influence on processability, polymer morphology, and optical properties. Herein, we report the stereoretentive ring-opening metathesis polymerization (ROMP) of [2.2]paracyclophane dienes bearing either a linear alkyl substituent or a branched alkoxy substituent to form all-cis PPVs with great solubility in organic solvents. The introduction of 2-ethylhexyloxy side-chains permits the preparation of PPV with uncharacteristically high molar masses (up to 108.8 kg/mol) for a polymerization with living characteristics. Exposure to UV light (365 nm) rapidly induces isomerization of all-cis alkenes leading to the formation of all-trans PPV. This study proposes an attractive strategy to synthesize soluble all-cis and all-trans PPVs with tunable, high molar masses through careful design of the ROMP monomer.

中文翻译：

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通过具有各种芳基取代基的[2,2]对环芳二烯的立体保持开环复分解聚合获得具有高摩尔质量和快速光异构化速率的全顺式聚（对苯撑乙烯）

聚对苯撑乙烯 (PPV) 是学术界和工业界研究最广泛的共轭聚合物之一，但大多数生产方法缺乏对摩尔质量和烯烃立体化学的精确控制。这些关键参数对加工性能、聚合物形态和光学性能有很大影响。在这里，我们报道了带有直链烷基取代基或支链烷氧基取代基的 [2.2] 对环芳二烯的立体保持性开环复分解聚合 (ROMP) 形成全顺式PPV 在有机溶剂中具有很好的溶解性。2-乙基己氧基侧链的引入允许制备具有异常高摩尔质量（高达108.8 kg / mol）的PPV，用于具有活性特性的聚合。暴露于紫外光（365 nm）会迅速诱导全顺式烯烃异构化，从而形成全反式PPV。本研究提出了一种有吸引力的策略，通过仔细设计ROMP单体来合成具有可调、高摩尔质量的可溶性全顺式和全反式PPV。