Epoxy resins rank among the most significantly used thermosets, showing high thermal and mechanical properties. Unfortunately, current polymerization processes to reach these properties are energy-intensive, characterized by high temperatures and long processing duration. Addressing this problem, recent years have witnessed the emergence of curing methods under mild and ecofriendly conditions, aligning with societal and ecological challenges. Mild conditions were delineated in this review as a polymerization without solvent and at temperatures not exceeding 80 °C. This work highlights three methods, by focusing on research works from 2015 to date: i) polyadditions via step-growth ring opening polymerization, ii) photopolymerization leading to homopolymerization of bio-based monomers and iii) redox polymerization achieved through the release of cations or acidic protons species, initiating the cationic polymerization. In the context of ecofriendly conditions, the replacement of bisphenol-A present in many epoxy monomers is also a huge challenge to keep both good mechanical properties and fast polymerization kinetics. In this context, this review aims at underlining the increasing importance of epoxy curing under mild conditions, in possible combination with bio-based monomers for bisphenol-A replacement and to guide both researchers and industries to explore and develop new curing systems.

中文翻译：

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在温和和环保的条件下进行环氧树脂固化：迈向无双酚 A 体系


环氧树脂是应用最广泛的热固性材料之一，表现出高热性能和机械性能。不幸的是，目前达到这些特性的聚合工艺是能源密集型的，其特点是高温和较长的加工时间。为了解决这个问题，近年来见证了在温和和环保条件下的固化方法的出现，这与社会和生态挑战相一致。在本综述中，温和条件被描述为无溶剂且温度不超过 80 °C 的聚合反应。 这项工作重点介绍了 2015 年至今的研究工作，重点介绍了三种方法：i） 通过阶梯生长环开环聚合进行加聚，ii） 光聚合导致生物基单体的均聚，以及 iii） 通过释放阳离子或酸性质子物质实现氧化还原聚合，引发阳离子聚合。在环保条件下，替代许多环氧单体中存在的双酚 A 对于保持良好的机械性能和快速聚合动力学也是一个巨大的挑战。在此背景下，本综述旨在强调在温和条件下环氧树脂固化的重要性日益增加，可能与生物基单体结合以替代双酚 A，并指导研究人员和工业界探索和开发新的固化系统。