不同辐照剂量壳聚糖酰化改性产物的结构和性质比较

Structures and Properties of Chitosan Acylation Products after Irradiation with Different Doses

将不同辐照剂量的壳聚糖进行酰化改性,然后分别测定改性前后壳聚糖水溶性和粘度,并通过傅里叶红外光谱仪(FT-IR)、热重-差热综合分析仪(TG/DTA)、粉末X-衍射仪(XRD)和电子扫描电镜仪(SEM)对其结构进行表征。结果表明:辐照剂量越大,壳聚糖酰化改性产物产率越低;与壳聚糖相比,未辐照的酰化改性后壳聚糖水溶性和分子量大大增加,粘度明显下降;而随着辐照剂量的增加,经过辐照的酰化改性后壳聚糖水溶性和分子量没有明显的变化,粘度明显降低。FT-IR和TG/DTA图表明酰化改性后壳聚糖分子中成功引入了亲水基团(羧基),XRD和SEM图分别显示酰化改性后壳聚糖晶体结构被破坏,呈现疏松多孔结构,改性后壳聚糖的结构更有利于水分子的进入。结构决定性质,结构变化必然引起性质的变化。进行壳聚糖酰化改性产物结构和性质的比较,对壳聚糖的进一步应用具有理论参考价值。

Chitosan samples irradiated with different doses were modified by acylation, and then their water solubility and viscosity were determined. In addition, the structures of acylated products were characterized by Fourier transform infrared spectroscopy（FTIR）, thermogravimetric/differential thermal analysis（TG/DTA）, powder X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results indicated that the yield of chitosan acylation products decreased with increasing irradiation dose. Compared with chitosan, the water solubility and weight-average molecular mass of non-irradiated chitosan acylation products increased significantly and the corresponding viscosity declined dramatically. However, with increasing irradiation dose, the water solubility and weight-average molecular mass of irradiated chitosan acylation products showed no obvious changes, but the corresponding viscosity reduced significantly. FT-IR spectra and TG/DTA curves indicated that the hydrophilic group（carboxyl） was successfully introduced into chitosan via acylation. Meanwhile, XRD patterns and SEM images showed that the crystal structure of modified chitosan was damaged and porous structures were observed, which promotes the entrance of water molecules. Structure and properties are closely related; therefore, structural changes inevitably lead to changes in properties. Comparing the properties and structures of chitosan and its acylation products can provide a certain theoretical reference value for further applications of chitosan.