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The thermogravimetric analysis (TGA) and differential scanning calorimetric analysis (DSC) were used to study the thermal degradation of poly(acrylic acid) PAA and poly(acrylamide) PAAm as well as the compound obtained from their interactions. The examination of the thermal curves revealed that the characteristics of the curves of the compound resulting from the cooperative interactions are different from those of the constituent polymers. The differences in the characteristics of the thermal curves were attributed to the formation of an interpolymer complex resulting from the interaction of PAA with PAAm at low pH value. These two thermal techniques were also used to investigate the thermal behavior of the compounds obtained from the interaction of PAA and (PAAPAAm) mixture with bone powders (BP) and hydroxyapatite (HA). It was found that the TGA, DTG, and DSC curves do not show the peak of formation and degradation of PAA anhydride which provided strong evidence for the consumption of PAA in the reaction between the polymer and BP. The interaction between PAA and the thermally treated BPs and HA was investigated. Moreover the interaction between the mixture of PAA and PAAm at different pH values and the BPs and HA was discussed.

Nanoparticles hydroxyapatite (HAp) was prepared via an in situ biomimetic process with polyacrylic acid (PAAc) as a host polymeric material. Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry were used to test the physical and chemical characteristics of biocomposites. The formation of HAp is confirmed by energy dispersion X-ray analysis. Chemical binding between inorganic HAp and PAAc was investigated and discussed. HAp formation was initiated through the interaction of Ca 2þ ions with the negative side groups of the polymer surface. The results showed that the biocomposites were formed with good homogeneity and thermal stability. Nanoparticles of HAp were uniformly distributed in the polymeric matrices. The resulting new materials are hoped to be applicable in the biomedical fields.

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