Integration of Halochromic <scp>PLA</scp>/<scp>PBAT</scp> Blends in <scp>3D</scp> Printing Technologies

ABSTRACT Halochromic polymers offer innovative pH‐sensing capabilities essential for smart applications in environmental monitoring and biomedical diagnostics. In this study, we enhance the compatibility of poly(lactic acid) (PLA) and poly(butylene adipate terephthalate) (PBAT) blends for fused deposition modeling (FDM) by incorporating 3‐Glycidoxypropyltrimethoxysilane (GPTMS) as a reactive compatibilizer and methyl orange (MO) dye as a halochromic agent. Halochromic polymer filaments were prepared via twin‐screw extrusion, blending PLA and PBAT at 80PLA/20PBAT and 20PLA/80PBAT ratios, with 5 phr GPTMS and 0.03 wt% methyl orange (MO) dye. The filaments were 3D printed and analyzed for mechanical, thermal, and morphological properties. The introduction of GPTMS facilitates the formation of new ester and ether linkages at the polymer interface, as evidenced by the increased intensity of CO stretching peaks in FTIR spectra, which correlates with improved interfacial adhesion and enhanced mechanical properties such as tensile strength and elongation at break. In PLA‐rich regions, GPTMS induces a slight increase in the glass transition temperature ( T g ) and reduces the cold crystallization enthalpy, indicative of a more organized yet less flexible structure, while in PBAT‐rich phases, GPTMS markedly enhances crystallinity and promotes a well‐defined melting peak due to PBAT's strong nucleating effect. Furthermore, the incorporation of MO dye subtly lowers T g and modifies the crystalline structure, aligning with FTIR observations and mechanical performance variations. These synergistic effects ultimately optimize both the thermal and functional properties of the blend, making it a promising candidate for advanced multifunctional applications.