With microstructures that typically favor crystallization at low temperatures, commercial polybutadiene elastomers often suffer from poor toughness and limited elongation when utilized in applications near room temperature. By controlling competition between primary and secondary metathesis through phosphite inhibition of ruthenium catalysts during the ring-opening metathesis polymerization of cyclooctadiene and a bis-norbornene cross-linker, we effectively tune the proportion of cis and trans alkenes and the resulting polybutadiene microstructure. With microstructural control, a wide range of room temperature mechanical responses are revealed by simply tuning the phosphite to catalyst ratio. Importantly, toughening due to the presence of crystalline domains initially or those formed in situ through strain-induced crystallization is possible at room temperature, and polybutadiene elastomers with room temperature elongation at failure greater than 600% are obtained. Further, strain-mediated crystallization allows for storage of strain energy and on-demand actuation upon application of a mild thermal stimulus. Our results suggest a scalable synthetic route to high-toughness polybutadiene elastomers with a single catalytic system and hold promise for enabling excellent toughness in polybutadiene elastomers over a broad temperature range.

中文翻译：

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通过亚磷酸盐控制聚丁二烯弹性体的微观结构和机械响应抑制开环复分解聚合


由于微观结构通常有利于在低温下结晶，因此在接近室温的应用中使用时，商业聚丁二烯弹性体的韧性通常较差且伸长率有限。在环辛二烯和双降冰片烯交联剂的开环复分解聚合过程中，通过亚磷酸盐抑制钌催化剂来控制初级和次级复分解之间的竞争，我们有效地调节了顺式和反式烯烃的比例以及所得的聚丁二烯微观结构。通过微观结构控制，只需调整亚磷酸盐与催化剂的比例，即可揭示广泛的室温机械响应。重要的是，由于最初存在晶畴或通过应变诱导结晶原位形成的晶畴而引起的增韧是在室温下可能的，并且可以获得失效时室温伸长率大于 600% 的聚丁二烯弹性体。此外，应变介导的结晶允许在施加温和的热刺激时存储应变能和按需驱动。我们的结果表明，具有单一催化系统的高韧性聚丁二烯弹性体的可扩展合成路线有望在较宽的温度范围内实现聚丁二烯弹性体的出色韧性。