偶氮苯型侧链液晶聚合物的阻隔特性研究

合成了偶氮苯侧链液晶聚合物聚甲基丙烯酸(3-4-(4′-氰基偶氮苯)苯氧基]丙酯)(PM3ABCN),采用原位掠入射X射线衍射(GIXRD)方法研究了该聚合物膜在向列相和各向同性态(无定形相)时对气体的阻隔特性.并采用X射线能谱仪(EDS)分析铁片氧化后的氧含量,计算得到渗透通过聚合物膜的氧气的量.结果表明,当PM3ABCN膜处于各向同性态时,通过聚合物膜的氧气平均渗透量为1.92×10-3cm3 day-1m-2;而处于液晶态的膜对氧气的阻隔性提高了4.4倍,氧气平均渗透量为4.38×10-4 cm3day-1 m-2.结合样品表面的显微分析结果,探讨了液晶凝聚相结构对气体小分子的阻隔机理.

BARRIER PROPERTY OF AZOBENZENE-CONTAINING SIDE-CHAIN LIQUID CRYSTALLINE POLYMER

In order to study the properties of azobenzene-containing side-chain liquid crystalline polymer for preventing the permeation of small molecule,poly(3-4-(4′-cyanophenylazo) phenoxy]propyl methacrylate)(PM3ABCN) was synthesized in this study.The barrier properties of PM3ABCN was individually determined using in-situ glancing incidence X-ray diffraction(GIXRD) scanning technology under the amorphous state and the liquid crystalline(nematic) state.GIXRD was used to collect the metal surface oxidation,which is a quantitative result of oxygen permeated through the polymer films covering the metal surface.The content of oxygen element in oxidized iron matrix samples was analyzed by means of X-ray energy dispersive spectroscopy(EDS),and the amount of oxygen permeated through the synthesized polymer films was calculated based on the results gained from the XRD patterns and EDS analysis.The results indicated that the average permeation rate of oxygen through the PM3ABCN films was 1.92 × 10-3 cm3day-1 m-2 and 4.38 × 10-4 cm3day-1 m-2 under the isotropic phase and liquid crystalline phase respectively,and the permeation property of liquid crystalline PM3ABCN was 4.4 times slower than that of the amorphous state.In combination with the results of microscopic analysis on the specimen surface,the barrier mechanism of condensed state structure in liquid crystalline PM3ABCN was also investigated.