Vitrimers represent an environmentally friendly class of materials, which behave like thermosets at room temperature but exhibit thermoplastic flow behavior when heated, making them processable and recyclable, thus extending material life and reducing waste. However, to fully meet the current demand for a sustainable economy, biodegradability at the end of the material life should also be considered, a property that not all vitrimers possess. Based on the above issues, this work aimed to develop biodegradable vitrimers based on polycaprolactone (PCL), a biodegradable polyester potentially derived from biomass fermentation. In detail, three different ad hoc synthesized star-shaped acrylated PCLs, characterized by different number of arms and molecular weight, were synthesized and used to prepare vitrimeric systems. Indeed, the above polymers were cross-linked with a fast exchangeable diboronic ester dithiol (2,2′-(1,4-phenylene)-bis[4-mercaptan-1,3,2-dioxaborolane], DBEDT), in solventless conditions. The formation of a dynamic network was proven by Fourier transform infrared, differential scanning calorimetry, thermogravimetric analysis, gel fraction, rheological, and dynamic mechanical analyzer measurements. In particular, the activation energies for the relaxation process of these materials were verified by rheological measurements in the range 44–62 kJ/mol. Moreover, all vitrimers, which were completely degraded by enzymatic hydrolysis within 12 days, exhibited excellent recyclability and self-healing properties when heated to 180 °C before processing.

中文翻译：

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基于聚己内酯的可持续 Vitrimer

Vitrimers 代表了一类环保材料，其在室温下的行为类似于热固性材料，但在加热时表现出热塑性流动行为，使其可加工和可回收，从而延长材料寿命并减少浪费。然而，为了充分满足当前可持续经济的需求，还应该考虑材料寿命结束时的生物降解性，这是并非所有玻璃体都具备的特性。基于上述问题，本工作旨在开发基于聚己内酯（PCL）的可生物降解的玻璃体，聚己内酯（PCL）是一种可能源自生物质发酵的可生物降解聚酯。具体来说，合成了三种不同的临时合成的星形丙烯酸酯化PCL，其特征在于不同的臂数和分子量，并用于制备玻璃化系统。事实上，上述聚合物与快速可交换的二硼酸酯二硫醇（2,2'-(1,4-亚苯基)-双[4-硫醇-1,3,2-二氧硼杂硼烷]，DBEDT）在无溶剂中交联状况。动态网络的形成通过傅里叶变换红外、差示扫描量热法、热重分析、凝胶分数、流变学和动态机械分析仪测量得到证明。特别是，这些材料松弛过程的活化能通过流变测量验证在 44-62 kJ/mol 范围内。此外，所有的vitrimer在加工前加热至180℃时，均在12天内通过酶水解完全降解，表现出优异的可回收性和自修复性能。