Preparation of microporous carbon materials via in-depth sulfonation and stabilization of polyethylene

Microporous carbon material was fabricated via the in-depth sulfonation and carbonization of commercial polyethylene (PE) pellets for the first time. The change in thermal-stability, chemical structure, crystallinity and morphology of PE during the fabrication process was systematically analyzed. Porous polyethylene (PPE) clumps were firstly fabricated in a toluene/water mixed system via reprecipitation. Due to the efficient and homogenous sulfonation of PPE, the thermal-stability of sulfonated PE was improved significantly, with a weight retention as high as 51.9% at 700 °C. Sulfonation lead to the appearance of alkenyl and aromatic carbons. differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses showed that the crystallinity of PE decreased significantly after sulfonation. The crystallinity results obtained from DSC are much lower than those from XRD due to the decomposition involved in the DSC testing. Furthermore, many new pores were formed in PPE during sulfonation and the subsequent loss of the sulphonate groups. These pores were further expanded during the carbonization process which may be due to the direct solid weight loss as well as the fast diffusion of the gases produced in pyrolysis. This study opens a simple and new approach for the fabrication of microporous carbon material via in-depth sulfonation of PE.