Synthesis and structure–property relationships of PVAc–VAE hybrid polymers: a comparative evaluation of in situ and physical blending methods

Hybrid polymer emulsions were synthesized through a semi-batch emulsion polymerization process using vinyl acetate monomer in the presence of commercial ethylene vinyl acetate (VAE) emulsion. Comparative studies were conducted by preparing physical blends of polyvinyl acetate (PVAc) and VAE emulsions in equivalent ratios. The influence of VAE incorporation on PVAc performance was systematically investigated through both in situ polymerization and blending methodologies. Thermal and viscoelastic properties were characterized using differential scanning calorimetry and dynamic mechanical analysis, while morphological assessments were carried out via scanning electron microscopy (SEM). SEM revealed enhanced miscibility and unimodal particle size distribution in hybrid systems synthesized through in situ polymerization, in contrast to the more heterogeneous morphology of physically blended counterparts. The novelty of this work lies not in the incorporation of VAE into PVAc, which has been previously reported, but in the systematic comparison of in situ seeded emulsion polymerization and conventional physical blending at comparable PVAc/VAE compositions. The effect of the hybridization route on particle morphology, thermal transitions, rheological behavior, viscoelastic properties, and adhesive performance was systematically investigated. The results demonstrate that the synthesis route strongly influences particle-level structural integration and consequently governs the balance between cohesive strength, flexibility, interfacial wetting, and adhesion. In situ polymerized systems exhibited greater structural homogeneity and generally superior performance compared with physically blended systems at equivalent nominal compositions.