荧光法研究交联聚苯乙烯氯甲基化过程的结构形态衍变

本文以St/DVB凝胶、St/DVB超髙交联凝胶为参比网络结构,用荧光光谱方法跟踪研究了St/DVB交联凝胶氯甲基化反应过程中网络结构形态的衍变.发现随着凝胶中氯百分含量的增加,其苯基激基缔合物320nm荧光谱带趋于消失;在最初反应阶段.苯基多环聚集体420nm荧光谱带强度迅速上升.而后急剧下降,同时在488nm左右出现一新的荧光谱带,与超高交链凝胶荧光谱带相近似:红外光谱证实了氯甲基化凝胶中亚甲基交联桥的增加.结果表明,伴随氯甲基化反应发生的后交联反应可使交联凝胶疏松网络区结构趋向紧密,使溶剂难以逾渗的微凝胶核松弛解体,从而使St/DVB交联凝胶网络涨落趋向均匀.

Fluorescence Studies on Morphological Change of St/DVB Crosslinked Gels During Chloromethylation

The morphological change of St/DVB crosslinked gels during chloromethylation was studied by fluorescence spectroscopy using St/DVB crosslinked and hypercrosslinked gels as control samples. It has been found that with increase of chlorine content, the excimer emission band (~325nm) approaches to vanish, while the intensity of multi-ring aggregate emission band (~420nm) quickly reaches a maximum,and then decreases sharply accompanied by appearance of a new broad band centred at ca 488nm which roughly coincides with the typical emission band of hypercrossllinked St/DVB gels. Mearwhile, the result of IR measurement suggests that methylene bridge between phenyl rings forms and increases with chloromethylation process. These results are explained in terms of a side reaction of post-crosslinking, which densifies the loosely crosslinked networks and undoes the densely entangled microgel nuclei. As a result, the morpology of the crosslinked gels becomes more homogeneous with chloromethylation.