国内精品国产三级国产在线专_欧美日韩在线播放一区二区_成人xxxx视频_欧美激情视频一区_色女人综合av_久久久亚洲影院_久久久久久九九_成人免费网站在线_日韩美女毛茸茸_狠狠干一区二区

Risedronate-anchored hydroxyapatite (HA-RIS) nanocrystals were prepared with 4.1 wt % RIS and used for controlled surface-initiated ring-opening polymerization (ROP) of L-lactide (L-LA). The strong adsorption of RIS to HA surface not only led to enhanced dispersion of HA nanocrystals in water as well as in organic solvents but also provided alkanol groups as active initiating species for ROP of L-LA. HA-RIS was characterized by thermogravimetric analysis, dynamic light scattering, ¹H NMR, Fourier transform infrared spectrometer, and X-ray diffraction. The graft polymerization of L-LA onto HA-RIS took place smoothly in the presence of stannous octoate in toluene at 120 °C, resulting in HA/poly(L-LA) nanocomposites with high yields of 85–90% and high poly(L-LA) contents of up to 97.5 wt %. Notably, differential scanning calorimetry measurements revealed that the poly(L-LA) in HA/poly(L-LA) nanocomposites exhibited considerably higher melting temperatures (T_m = 173.3−178.1 °C) and higher degrees of crystallinity (X_c = 41.0−43.1%) as compared to poly(L-LA) homopolymer (T_m = 168.5 °C, X_c =25.7%). In addition, our initial results showed that these HA/poly(L-LA) nanocomposites could readily be electrospun into porous matrices. This study presented a novel and controlled synthetic strategy to HA/RIS/poly(L-LA) nanocomposites that are promising for orthopedic applications as well as for bone tissue engineering. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.