A new method transforms waste PET plastic into monolithic materials with impressive mechanical strength and stability under extreme conditions

It has always been a great challenge to transform the huge waste PET plastic (wPET) resources into reusable monolithic materials under atmospheric pressure and low temperature. Herein, we reported a novel one-step method for transforming wPET into 3D monolithic structure material (3DMSM) at atmospheric pressure and low temperature (98 °C) without catalyst. The main idea of this paper is to use special solvent (a mixture of C6H5OH and C2H2Cl4 with a 1:1 vol ratio) to dissolve wPET, then introduce polymethyl methacrylate (PMMA) and aluminum dihydrogen phosphate (AHP) to react and generate new chemical bonds in 3DMSM, so as to transform wPET into 3DMSM with excellent mechanical strength and stability even under extreme conditions. The resulting 3DMSM (0.546 g) can support a beaker containing 5000 mL of water without deformation, and max compressive strength and compressive modulus reaches 5.5 ± 0.5 MPa and 34.3 ± 0.5 MPa 3DMSM can maintain structural stability in extreme conditions such as strong acid and alkali. XRD, FTIR and 13C solid-state NMR analysis confirmed that the chemical bonds of wPET will not break when dissolved in a special solvent, and chemical bond breakage mainly occurred in the reaction process. Utilizing chemical bonds to break and recombine, two new substances, C9H9ClO3 (benzoicacid, 5-chloro-2-methoxy-, methylester) and Al3(PO4)2(OH)3, were formed, and the possible structure formula was provided. The innovation of this work is that it presents a novel method to dispose of wPET at atmospheric pressure and low temperature, which provides a possibility for the subsequent large-scale realization of wPET resources.