辐射合成聚丙烯酰胺、聚丙烯酸钠及其共聚物水凝胶微观结构的扫描电镜研究

Studies on Microstructure of Radiation-Synthesized PAM, PNaA and P(AM-NaA) Copolymer Hydrogels by Scanning Electron Microscope

用６０Ｃｏ－γ射线辐射合成了低交联度的聚丙烯酰胺、聚丙烯酸钠及丙烯酰胺－丙烯酸钠共聚物水凝胶，用扫描电子显微镜研究了水凝胶经过丙酮脱水的干态试样的微观结构特征。发现聚合物中丙烯酰胺与丙烯酸钠单体单元的比例对其微观结构影响很大，并且从聚合物链段之间存在氢键和静电排斥这两种对立作用力相对强度的角度，定性地阐述了各水凝胶微观结构之间的差异。

The polymer hydrogels polyacrylamide (PAM),poly sodium acrylate (PNaA) and P(AM-NaA) in different AM/NaA monomer unit ratios with lower crosslinking densities were synthesized by 60Co-γ ray radiation polymerization in aqueous solutions.The microstructure of these dry hydrogel samples in which water was extracted by acetone was observed by scanning electron microscope, The results indicate that different ratios of AM/NaA in these homopolymer and copolymer hydrogels have much influence on their microstructure. It is attributed to the relative strength of two kinds of opposite forces──hydrogen bond attraction and electrostatic repulsion which exist in chain segments of polymers. However,the relative strength depends on different ratios AM/NaA,and finally affects the ways of polymer chain packing. As a result, there are obvious differences in microstructure between homopolymers and copolymers.