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

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-CaCO 3 /PBAT) composite through internal mixing. Chemical structure analysis revealed that CPS adsorbed onto the surface of nano-CaCO 3 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-CaCO 3 and PBAT resulted in enhanced crystallinity, tensile stress, and elongation at break. By incorporating only 0.4 wt% CPS into 10 wt% nano-CaCO 3 (based on PBAT weight), the dispersion of nano-CaCO 3 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-CaCO 3 modified via the adsorption and dispersion of CPS. Stress and elongation of PBAT composite reinforced by CPS-modified nano-CaCO 3 . CPS-modified nano-CaCO 3 /PBAT composite films processed through blow molding. Enhancement by coordination, hydrogen-bond action, and microphase separation.