The moderation of the dielectric properties of polymer composites and their environmental stability need to be considered comprehensively in the design of microwave-absorbing materials. In this work, polypyrrole/polystyrene (PPy/PS) composited particles were synthesized through a facile in situ bulk polymerization procedure. The PS component can be modulated conveniently by controlling the polymerization time. FTIR and Raman analyses disclosed that the PS component was immobilized in PPy via covalent bonds. The electromagnetic characterization results indicated that the dielectric properties and, thus, the microwave absorption could be controlled when the styrene polymerization was prolonged from 6 h (PPy-6) to 19 h (PPy-19). The composite PPy-19 displayed an optimal reflection loss of -51.7 dB with a matching thickness of 3.16 mm, and the effective absorption bandwidth (EAB) even reached 5.8 GHz at 2.4 mm. The PS component endowed PPy/PS composites with more robust environmental stability than homogeneous PPy. After being exposed to air for 365 days and hydrothermally treated at 100 °C for 12 h, PPy-19 still exhibited a reflection loss superior to -20 dB. The present work provides a new insight into the adjustment of the electromagnetic properties of PPy composites to fabricate high-performance microwave absorbers with superior environmental stability.
Keywords: in situ bulk polymerization; microwave absorption; polypyrrole composite; polystyrene.