Preparation and properties of phosphogypsum/amino acid copolymer porous composite for medical application

Phosphogypsum (PG) materials with the ratio of calcium and phosphorus (Ca/P) of 1.50 and 1.67 were synthesized by the chemical coprecipitation, poly(lactide-amino acid) copolymer (PAA4) was synthesized through the melt polycondensation, and two kinds of PG/PAA4 porous composites for the medical application with Ca/P of 1.50 and 1.67 were prepared by the extrusion foaming method. The morphology, microstructure and composition of the composites were characterized by TGA、XRD、IR、SEM、EDS, and the in vitro degradability of the composites were investigated through phosphate buffer solution (PBS). The results show that the porous composites have good uniformity with the phosphogypsum of around 60% (mass fraction) dispersed in the PG/PAA4 composites. The porous composites have the pore size ranging from 100 to 400 μm with the porosity of 60%. Some chemical interactions occur between the inorganic (PG) and organic phases (PAA4) in the composites. The composites exhibit good degradability in PBS and their degradability is enhanced by the increase of the Ca/P of PG. No obvious change of pH value of the solution is found during the composites soaking into PBS, which ranges from 6.9 to 7.4. Presumably, the composites have bioactivity with the apatite deposited on their surfaces after soaking in PBS.