The development of robust methods for the synthesis of chemically recyclable polymers with tunable properties is necessary for the design of next-generation materials. Polyoxazolidinones (POxa), polymers with five-membered urethanes in their backbones, are an attractive target because they are strongly polar and have high thermal stability, but existing step-growth syntheses limit molar masses and methods to chemically recycle POxa to monomer are rare. Herein, we report the synthesis of high molar mass POxa via ring-opening metathesis polymerization of oxazolidinone-fused cyclooctenes. These novel polymers show <5% mass loss up to 382–411 °C and have tunable glass transition temperatures (14–48 °C) controlled by the side chain structure. We demonstrate facile chemical recycling to monomer and repolymerization despite moderately high monomer ring-strain energies, which we hypothesize are facilitated by the conformational restriction introduced by the fused oxazolidinone ring. This method represents the first chain growth synthesis of POxa and provides a versatile platform for the study and application of this emerging subclass of polyurethanes.

中文翻译：

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通过开环易位聚合获得可化学回收的高摩尔质量聚恶唑烷酮


开发合成具有可调性能的化学可回收聚合物的稳健方法对于下一代材料的设计是必要的。聚恶唑烷酮 (POxa) 是一种主链具有五元氨基甲酸酯的聚合物，是一个有吸引力的目标，因为它们具有强极性且具有高热稳定性，但现有的逐步增长合成限制了摩尔质量，并且以化学方式将 POxa 回收为单体的方法很少。在此，我们报道了通过恶唑烷酮稠合环辛烯的开环复分解聚合合成高摩尔质量 POxa。这些新型聚合物在高达 382–411 °C 的温度下质量损失 <5%，并且具有由侧链结构控制的可调玻璃化转变温度 (14–48 °C)。尽管单体环应变能较高，但我们证明了化学回收到单体和再聚合的简便性，我们假设这是由稠合恶唑烷酮环引入的构象限制促进的。该方法代表了 POxa 的首次链增长合成，并为这一新兴聚氨酯子类的研究和应用提供了一个多功能平台。