Enhanced poly(butylene adipate‐co‐terephthalate) composite films reinforced with nano‐calcium carbonate modified by a comb‐like polyacrylic superdispersant

Abstract A comb‐like polyacrylic superdispersant (CPS) consisting of polyacrylic acid‐co‐poly(isobutyl alcohol polyoxyethylene ether) (PBAT) was synthesized as a dispersant for preparing nano‐calcium carbonate/PBAT (nano‐CaCO₃/PBAT) composite through internal mixing. Chemical structure analysis revealed that CPS adsorbed onto the surface of nano‐CaCO₃ via coordination between carboxyl groups and calcium ions, effectively dispersing particles using a comb‐shaped side chain and electrostatic repulsion. This improved compatibility between nano‐CaCO₃ and PBAT resulted in enhanced crystallinity, tensile stress, and elongation at break. By incorporating only 0.4 wt% CPS into 10 wt% nano‐CaCO₃ (based on PBAT weight), the dispersion of nano‐CaCO₃ was significantly improved, leading to a superior two‐phase interface in the composite material. Consequently (in the film's machine direction), elongation at break increased from 882 ± 49% to 1047 ± 31%, while tensile strength increased from 22.10 ± 2.06 MPa to 26.70 ± 1.14 MPa. These findings facilitate the production of high‐performance PBAT composites suitable for blow molding into biodegradable films. Highlights Comb‐like polyacrylic superdispersant synthesized by aqueous polymerization. Nano‐CaCO₃ modified via the adsorption and dispersion of CPS. Stress and elongation of PBAT composite reinforced by CPS‐modified nano‐CaCO₃. CPS‐modified nano‐CaCO₃/PBAT composite films processed through blow molding. Enhancement by coordination, hydrogen‐bond action, and microphase separation.