Janus nanoparticle interfacial modulation for enhanced PP/PMMA composites performance: A mechanistic elucidation via fluorescence tracing

The compatibility of polypropylene (PP) and poly(methyl methacrylate) (PMMA) critically governs their properties, yet inherent immiscibility causes phase separation and weak interfacial adhesion. To overcome these limitations and simplify compatibilization, amphiphilic fluorescent Janus nanoparticles (TPE@Janus NPs) were synthesized via emulsion polymerization and applied as a novel compatibilizer in PP/PMMA blends prepared by melt blending. Fluorescence tracing confirmed preferential localization of TPE@Janus NPs at the PP/PMMA interface, which reduced interfacial energy and inhibited phase separation. At an optimal loading of 0.9 wt%, the PMMA domain size decreased by 42 %, while impact and tensile strengths increased by 31 % and 23 %, respectively. Thermal stability was also enhanced, with T 50 increasing by nearly 150 °C (from 410.8 to 557.0 °C). This study establishes the dual functionality of TPE@Janus NPs—as a highly effective compatibilizer and an in situ fluorescent probe for interfacial dynamics—offering a practical strategy for the rational design of advanced polymer composites with tailored interfacial properties.