Surface Modification of a PET Substrate Through the Controlled Graft Polymerization and Application to the PET / Apatite Hybrids Formation

Organic ⁄ inorganic hybrid materials have attracted much attention because they are capable of combining the characteristic features of both organic and inorganic substances. This study aims to fabricate novel hybrids consisting of PET and apatite as components and to improve the mechanical properties of the hybrid through designing the interfacial structure between PET and an apatite layer. To this end, a PET substrate was modified with graft polymer chains bearing Si(OCH3)3 functions through the surface-initiated atom transfer radical polymerization (ATRP) and then subjected to the hybrid formation with apatite by a process mimicking biomineralization. This process was achieved by soaking the surface-modified PET substrate in a simulated body fluid (SBF) with ion concentrations nearly equal to human blood plasma. In this study, the PET substrate was modified with hyperbranched graft polymers with pendant Si(OCH3)3 functions, then coated with a calcium silicate gel and finally soaked in SBF for 3d to form the target PET ⁄ apatite hybrid. To evaluate the effects of the surface modification with grafted polymers on the mechanical properties of the PET ⁄ apatite hybrid, the interfacial bond strength between the PET substrate and the apatite layer was estimated by a peel test using a commercial adhesive tape.