Experimental investigation of interfaces in hydroxyapatite/polyacrylic acid/polycaprolactone composites using photoacoustic FTIR spectroscopy
✍ Scribed by Devendra Verma; Kalpana Katti; Dinesh Katti
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 451 KB
- Volume
- 77A
- Category
- Article
- ISSN
- 1549-3296
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✦ Synopsis
Abstract
Molecular interactions in hydroxyapatite (HAP) polymer composites have been studied using photoacoustic spectroscopy. HAP is mineralized by wet precipitation under two conditions: first is in the absence of polyacrylic acid (PAAc) (ex‐situ HAP) and second in the presence of PAAc (in‐situ HAP). Porous and solid composites of ex‐situ and in‐situ HAP with polycaprolactone (PCL) have also been made to evaluate their applicability as bone scaffolds. Photoacoustic Fourier transform infrared (PA‐FTIR) spectroscopy studies indicate that both in‐situ and ex‐situ HAP have HPO~4~^2−^ in their structure, which leads to Ca^2+^ deficiency. During crystallization of in‐situ HAP, PAAc dissociates to form carboxylate ions, which binds to calcium ions and act as suitable site for nucleation for HAP crystallization. PA‐FTIR spectra of porous and solid composites indicate that porous composites adsorb more water, which is hydrogen bonded with carbonyl of PCL. Mechanical tests on solid samples indicate that ex‐situ HAP/PCL composites have higher elastic modulus than in‐situ HAP/PCL composites. However, in case of porous composites, in‐situ HAP/PCL composites are found to have higher elastic modulus. In‐situ HAP is chemically and structurally different from ex‐situ HAP. This modified HAP causes variation in microstructure of porous composite and hence alteration of its load transfer mechanisms and hence mechanical properties. © 2005 Wiley Periodicals, Inc., J Biomed Mater Res, 2006