聚苯乙烯基偶氮聚合物的合成研究

改进了聚苯乙烯的硝化、还原、重氮化和偶合反应路线 (NRDC) ,使每步反应都得到很高的产率 ,并利用大分子重氮盐 (MDS)分别与苯胺、N 烃基苯胺和酚等三类化合物偶合 ,得到相应的聚苯乙烯基偶氮聚合物 .核磁共振分析结果证明了产物的高偶联率 .通过对大分子重氮盐热稳定性的研究 ,发现偶合反应之后需要一步加热反应以消除残余重氮基团 .还研究了这些聚合物的紫外 可见吸收光谱性质 ,氨 (胺 )基偶氮产物的水溶液表现出了明显的pH敏感性

SYNTHESIS AND CHARACTERIZATION OF POLYSTYRENE BASED AZO POLYMERS

Azo polymers were reported to be prepared from polystyrene through a nitration\|reduction\|diazotization\|coupling (NRDC) reaction route.However,azo\|coupling rates of the products were rather low because of the several steps of macromolecular reaction with low reaction yield in each step,or the obtained azo polymers could not be dissolved in any solvent due to the use of cross\|linked polystyrene as precursor.Recently,photoresponsive azo polymers have become actively researched objects,but no PS\|based azo polymers have been used as photo\|responsive polymers so far due to above reasons.In this work,three kinds of soluble polystyrene\|based azo polymers with high coupling rates have been synthesized through a modified NRDC procedure from polystyrene matrix.Both steps of the nitration and the reduction have nearly 100% reaction yields.Macromolecular diazonium salts (MDS) prepared were reacted with N alkyl aniline,substituted aniline and phenol type compounds through the azo coupling reaction.The intermediates and final products were characterized by 1H NMR,IR and UV\|Vis spectroscopy.Even though high coupling rates were obtained,diazonium salt groups could not be totally consumed due to the steric hindrance in the macromolecular reactions.The decomposition and cross\|linking of these residual diazo groups were found to be the reason for losing of solubility of the products.The thermolysis process of the diazonium salt group was studied and a heating step of reaction mixture was added after the azo coupling reaction.In this step,the unreacted diazo groups were converted to phenolic hydroxyl groups,which was found to be essential for preparing soluble PS\|based azo polymers.