Polyurethane coatings reinforced with poly(MMA-co-HPMA)@Mo2Ti2AlC3 as flexible EMI shielding solutions

Abstract

Lightweight materials, valued for their mechanical strength and efficiency, are widely applied in aerospace, automotive, civil, electronic, and biomedical fields. Recent advances in defense and high-speed communication technologies have intensified interest in their use for electromagnetic interference (EMI) shielding. This study explores the synthesis and characterization of flexible polyurethane (PUR) films embedded with reactive poly(methyl methacrylate-co-hydroxypropyl methacrylate)microparticles containing Mo₂Ti₂AlC₃ (MXenes). The poly(MMA-co-HPMA)@Mo₂Ti₂AlC₃ microparticles were prepared via suspension polymerization, utilizing the surface hydroxyl functionality to react with isophorone diisocyanate (IPDI) during PUR formation. This ensured uniform dispersion and stable incorporation of MXenes within the matrix. Characterization included FT-IR spectroscopy, SEM, XRD, DMA, mechanical testing, and EMI shielding evaluation. FT-IR confirmed successful copolymerization with complete monomer conversion. SEM revealed the microparticles as a well-dispersed phase within the PUR matrix, while XRD validated the intact MAX phase with minimal delamination. PUR films exhibited high flexibility and tensile resilience, reaching 0.7 MPa at ∼85% strain. EMI shielding improved with increasing microparticle concentration, with 2 wt% composites achieving 3 dB attenuation and reflecting 50% more power than lower-loaded samples in the 8.2–12.4 GHz range.