Plastics are nowadays essential to our daily life for a wide range of applications. In order to face the demand of polymer markets, given the depletion of fossil feedstocks from which they are still most commonly produced, and with the aim to develop more ecofriendly plastic materials, the need for renewable and/or recyclable polymers is huge. Polyhydroxyalkanoates (PHAs) are a class of polyesters that could meet the challenges of such a circular economy, as they currently stand as promising bio-based, degradable and recyclable alternatives to traditional non-degradable commodity polymers that are polyolefins. PHAs typically feature different side-chain substituents on the repeating units, which beside the stereochemistry along the polymer backbone and the intrinsic characteristics of the macromolecules, are key parameters that dictate and enable tuning of their thermal, mechanical, and recyclability performances. PHAs are thus a large family of versatile polymers that are currently of topical interest in light of their end-of-life options. This review discusses the chemical recycling of natural, biosynthetic and synthetic PHAs, mainly focusing on the most common examples, namely poly(3-hydroxybutyrate) (PHB), and its related copolymers. The most relevant non-biotechnological approaches, including pyrolysis-type processes, and solvolysis with especially hydrolysis and alcoholysis, whether they are catalyzed or not, are then addressed. The latest advances on the degradation, depolymerization and upcycling of PHAs, show promising outcomes for a close-carbon cycle economy with a favorable environmental impact, as exemplified from the most recent literature.

如今，塑料对于我们的日常生活至关重要，用途广泛。为了满足聚合物市场的需求，考虑到仍然最常生产聚合物的化石原料的枯竭，并且为了开发更环保的塑料材料，对可再生和/或可回收聚合物的需求是巨大的。聚羟基脂肪酸酯 (PHA) 是一类可以应对循环经济挑战的聚酯，因为它们目前是传统不可降解商品聚合物（聚烯烃）的有前景的生物基、可降解和可回收替代品。PHA 的重复单元通常具有不同的侧链取代基，除了沿着聚合物主链的立体化学和大分子的固有特性之外，这些取代基也是决定和调节其热、机械和可回收性能的关键参数。因此，PHA 是一个多功能聚合物大家族，目前因其报废选择而备受关注。本综述讨论了天然、生物合成和合成 PHA 的化学回收，主要关注最常见的例子，即聚（3-羟基丁酸酯）（PHB）及其相关共聚物。然后讨论最相关的非生物技术方法，包括热解型过程和溶剂分解，特别是水解和醇解，无论它们是否被催化。正如最新文献所证明的那样，PHA 降解、解聚和升级循环方面的最新进展显示了闭碳循环经济的良好成果，并具有良好的环境影响。