Chemically recyclable copolyesters from bio-renewable monomers: controlled synthesis and composition-dependent applicable properties

The development of chemically recyclable polymers is a promising solution to address the dual challenges of the environment and resources caused by petroleum-based plastics. Despite recent advancements, it is highly desirable for developing recyclable polymers to meet the requirements of both practical uses and well-performed recyclability. Bio-renewable monomers have been paid great attention recently as promising potential candidates for establishing a sustainable circular polymer economy. Herein, a sequential copolymerization of various bio-renewable n-alkyl substituted δ-valerolactone ((R)VLs) and p-dioxanone (PDO) is conducted to synthesize novel chemically recyclable diblock copolymers poly(p-dioxanone)-block-poly(n-alkyl-valerolactones) (PPDO-b-P(R)VLs) with well-defined and controlled structures. The properties of copolymers including thermal property, crystallization, mechanical property, hydrophilicity and transport property can be tuned effectively to meet the requirements of practical uses by alternating the alkyl substituents (R) and the P(R)VLs content. In addition, the high-efficiency and facile chemical recycling of copolymers to PDO and (R)VL comonomers is realized with a high yield of>96.5% and a high purity of 99%.