Structural, Mechanical and Morphological Characterizations of PMMA/PS Blends: Influence of Polystyrene on Poly(methyl methacrylate) Films

This study reports the structural, morphological, mechanical and dielectric behavior of solution-cast poly(methyl methacrylate) (PMMA) films containing trace fractions (0.5 and 1%) of polystyrene (PS). X-ray diffraction shows that all films are amorphous, exhibiting broad halos whose position reflects the average inter-chain spacing; PS incorporation shifts the halo slightly, indicating modestly looser chain packing rather than any crystalline change. FTIR and Raman spectroscopy reveal no new bands and only marginal shifts, confirming the absence of chemical bonding and consistent with the known immiscibility of PMMA and PS. Atomic force microscopy uncovers a composition-driven morphological transition: at 0.5% PS the surface develops a diffusion-limited dendritic network, which reorganizes into a phase-separated pore structure at 1%. Microhardness varies systematically with composition, and dielectric spectroscopy shows that ε′, ε″ and tanδ change measurably with PS content, which we attribute to interfacial polarization at the phase-separated domains. The results establish trace-PS addition as a simple route to tune the morphology and permittivity of PMMA films for dielectric-coating and flexible electronic applications.