RDF法对非晶态聚醚砜共聚物的近程有序结构研究

用径向分布函数(RDF)研究了聚醚砜共聚物(PES)在r=1.5 nm范围内的近程结构, 结果表明, 分子链间存在近程有序结构, 有序周期约为0.5 nm; 聚醚砜共聚物经退火处理后, 由g(r)图可以看出, 第一个峰变高、变窄; 由G(r)图可以看出, 分子链间第一个有序区内, 分子链间贡献大于链内贡献; 于200 ℃退火处理后有序畴尺寸(rs)略有增大, 原子平均位移(σ)变小, 使得分子链内原子间距分布更加均匀, 相邻分子链间距(rv)变小. 同时透射电镜(TEM)的形态结构分析表明, 经退火处理后, 其聚集态确实形成了某种局部有序的结构.

Investigation of Short Range Ordering in Amorphous PES Copolymer by Means of Radial Distribution Functions Derived from X-ray Diffraction

The short range order(0—1.5 nm) in polyether sulfone(PES) copolymer samples were studied. The result showed that two intra-molecular distances in the copolymer repeat unit were successfully resolved in the RDF pattern. However, there were only a suggestions of broad peaks at r≈0.55 nm and r≈1.1 nm attributable to intermolecular ordering, indicating that little intermolecular ordering occurred in either sample. The appearance of the two peaks at ~0.5 nm period suggested the existence of more or less parallel chain segments in PES copolymers. A annealed sample was examined to assess the sensitivity of the RDF method to short range intermolecular ordering. The RDF plot of this annealed sample showed a small variety compared with the quenched PES copolymer sample. The RDF parameter showed that the short range order in PES copolymer samples was essentially affected by the annealing procedures. The results of electron-microscopy investigation of PES copolymer sample, heat-treated at 200 ℃ for 72 h, indicate that the copolymer molecular aggregation is changed from a randomly coiled amorphous phase to an ordered one.