AbstractA new type of layered zirconium glycine‐N,N‐dimethylphosphonate (ZGDMP), with enlarged interlayer d‐spacing and a polar carboxylate group (COO–), was prepared and characterized by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), and scanning electron microscopy (SEM). ZGDMP was intercalated by n‐butylamine which further increased the d‐spacing to 1.76 nm. The modified ZGDMP (hereafter BA‐ZGDMP) was used as a nanofiller in a glycerol‐plasticized thermoplastic pea starch (PS) matrix. Compared with previous studies on PS/α‐ZrP, the present system of BA‐ZGDMP reinforced pea starch (PS/BA‐ZGDMP) presents two significant points: (i) the tensile strength was enhanced to 12.14 MPa, which was higher than that of the PS/ZrP system (9.44 MPa); and (ii) the moisture uptake of PS/BA‐ZGDMP was reduced to 59.1%, which was lower than that of the PS/ZrP system (63.1%). These results can be attributed to the introduction of functional carboxylate groups, which resulted in Van der Waals forces, stronger hydrogen bonding, and stronger interfacial adhesion and interaction between the polar BA‐ZGDMP and the polar starch matrix. POLYM. COMPOS., 31:1938–1946, 2010. © 2010 Society of Plastics Engineers.