Carbonated Nano Hydroxyapatite Crystal Growth Modulated by Poly(ethylene glycol) with Different Molecular Weights

The effects of poly(ethylene glycol) (PEG) molecular weights on nano hydroxyapatite (n-HA) crystal growth were studied, and a possible mechanism was proposed. n-HA crystals were synthesized in the presence of PEG with different molecular weights via hydrothermal method. Transmission electron microscopy (TEM) analysis showed that the presence of PEG increased the size of n-HA crystals; PEG with larger molecular weights produced larger n-HA crystals. High-resolution TEM observation indicated that all of the n-HA crystals tended to grow along the < 002 > axis. X-ray diffraction patterns showed that all of the samples consisted of only the HA phase. Besides, PEG increased the crystallinity of n-HA crystals, and this effect was more significant for PEGs with larger molecular weights. Fourier transform infrared results further revealed that all of the crystals were carbonated HA. Thermogravimetry/differential scanning calorimetry analysis detected PEG residues on n-HA particles mechanism of PEGs on n-HA crystal growth, n-HA samples heat-treated for various PEG20000, and a possible mechanism in which PEG modulated the growth of n-HA. To thoroughly study the modulating times were prepared in the presence of crystals was discussed.