TPPS在EVAL膜表面的吸附及超分子自组装

Adsorption of TPPS and supramolecular self-assembly on EVAL membrane surface

TPPS(四-(4-磺酸基苯基)卟啉)在一定条件下可以自组装形成超分子聚集体.将TPPS超分子聚集体与膜材料结合,可制备一种超分子负载膜.本实验以EVAL(乙烯-乙烯醇共聚物)为基膜,以DMAEMA(甲基丙烯酸N,N-二甲氨基乙酯)为单体,采用紫外接枝的方法制备了EVAL-g-PDMAEMA接枝膜,利用氢键、静电作用等非共价键作用将TPPS负载于EVAL原膜及EVAL-g-PDMAEMA接枝膜上.研究了pH值、离子强度、接枝率对吸附过程的影响及等温吸附机理.结果表明,当pH=3.6时接枝膜对TPPS的吸附容量最大,pH=7时,原膜对TPPS的吸附容量最大;离子强度的增大不利于膜对TPPS的吸附;EVAL-gPDMAEMA接枝率的增大,接枝膜对TPPS的吸附容量也随之增大;Langmuir吸附等温方程可以对吸附过程进行很好的描述.改变EVAL/TPPS负载膜的pH条件,利用紫外漫反射光谱表征膜表面TPPS的聚集状态,考察不同DMAEMA接枝率的负载膜实现超分子结构的条件.实验结果显示,当pH<1时,TPPS在接枝膜和原膜表面均形成超分子J-聚集体,而pH>1时,TPPS仅在接枝膜表面形成H-聚集;并且DMAEMA的接枝率越高,越有利于TPPS聚集体的形成,进而有利于超分子负载膜的构筑.

TPPS can spontaneously assemble into supramolecular aggregates under certain conditions. A supramolecular membrane was prepared based on TPPS supramolecular aggregates and membrane materials. In this paper, EVAL-g-PDMAEMA membrane was prepared by ultraviolet radiation grafting with EVAL as the raw membrane and DMAEMA as the monomer. The TPPS was loaded on EVAL and EVAL-g-PDMAEMA membrane via non-covalent as hydrogen bonds, electrostatic interactions, etc. The effects of pH, ionic strength and grafting degree on the adsorption process and isothermal adsorption mechanism of TPPS were studied. The results show that the maximum absorption of TPPS on the grafted membrane appeared at pH= 3.6, while on the raw membrane at pH= 7. The increase of ionic strength caused an adverse impact on the adsorption of TPPS on the membrane surface. While the adsorption amount of TPPS increasedwith the increase of EVAL-g-PDMAEMA grafting degree. The adsorption process can be well described by Langmuir isotherm model. The aggregation state of TPPS and the conditions of constructing asupramolecular structure were studied by changing the pH of the EVAL-g- PDMAEMA/TPPS membrane with aid in the method of UV reflectance spectroscopic. The results show that, at pH〈1, TPPS formed supramolecular Jaggregates on the EVAL and EVAL-g-PDMAEMA membrane surface, while at pH〉 1, only formed H- aggregates on EVAL- g- PDMAEMA membrane surface. Besides, the higher grafting degree of DMAEMA contributed to the formation of TPPS aggregates, further to the building of supramoleeular membrane.