*2.4. Characterization of RCMs and RPMs*

The RCMs and RPMs were investigated by FT-IR (MagnA-IR550, Thermo Fisher Scientific, Waltham, MA, USA) in the range 4000–400 cm−1. The analysis of the size and morphology of the RCMs and RPMs were performed using field-emission scanning electron microscopy (SEM, Supra 55 Sapphire, Carl Zeiss, Jena, Germany)). Thermogravimetric analysis of the RCMs and RPMs performed using TGA-DSC/DTA analyzer (STA 449 F5, NETZSCH-Gerätebau GmbH, Selb, Germany). The RCMs and RPMs were weighed by analytical balance with an accuracy of 0.1 mg (Practum124-1cn, Sartorius AG, Göttingen, Germany). The zeta potentials of the RCMs and RPMs were measured using a Laser Nanoparticle Size and Zeta Potential Analyzer (Zetasizer Nano, Malvern, UK). The RCM and RPM pore and specific surface area were measured at 77 k using surface area and pore size analyzer (ASAP2020, Micromeritics, Norcross, GA, USA). The mechanical properties of RCM were tested by an electronic universal testing machine (JDL-10000N, Yangzhou Tianfa test Machinery Co., Ltd., Yangzhou, China).
