红外光谱法研究磺化间规聚苯乙烯离聚物离子间相互作用

FT-IR SPECTROSCOPIC STUDIES OF IONIC INTERACTIONS IN SULFONATED SYNDIOTACTIC POLYSTYRENE IONOMERS

采用红外光谱法研究了不同金属阳离子及水合作用对磺化间规聚苯乙烯 (SsPS)离聚物阴、阳离子间相互作用的影响 .实验结果表明 :离间相互作用的强弱可通过红外光谱表现出来 ,SsPS离聚物中磺酸根阴离子 (SO-3 )的红外吸收谱带与金属阳离子的性质及离聚物所处的环境有关 .在干燥状态下 ,SsPS离聚物中磺酸根阴离子 (SO-3 )由于受到金属阳离子静电场作用的影响 ,S—O键被极化而使其对称伸缩振动和不对称伸缩振动吸收峰移向高波数 ,移动的幅度与金属阳离子的性质有关 .离聚物吸水后 ,由于水合作用的影响 ,金属阳离子的极化作用减弱 ,因而使S—O键相应的对称伸缩振动和不对称伸缩振动吸收谱带移向低波数 .对于未中和的磺化间规聚苯乙烯 (SsPS H)样品 ,水合作用会使磺酸基团部分离解 ,产生磺酸根阴离子 (SO-3 ) .在干燥状态下 ,磺酸基团仍以—SO3H形式存在 。

The effects of cation and hydration on cation\|anion interactions in sulfonated syndiotactic polystyrene(S s PS) ionomers were examined by FTIR spectroscopy.Ionic interactions in S s PS ionomers are reflected in their FTIR spectra directly,affecting the vibrations of the sulfonate anion.It is found that the counterion and hydration have a profound influence on cationanion interactions in the S s PS ionomers containing divalent transition metal cations (such as Mn 2+ ,Zn 2+ and Co 2+ ) and alkali metal cations (such as Na\++ and K\++).In the dry materials,the counterion imposes a strong electrostatic field on the sulfate anion that polarizes the S\_O dipole and shifts the asymmetric and symmetric vibrations of the sulfonate anion to higher frequencies.While in the hydrated materials,the polarization by the cation weakens and shifts the cooresponding vibrations to lower frequencies.For the unneutralized sulfonated syndiotactic polystyrene,in the hydrated form,the proton of the sulfonic acid is removed from the anion,yielding the sulfonate anion,SO\+-\-3.While in the dry form,the FTIR spectra of the sample exhibit characteristic absorbances of the sulfonic acid,\_SO\-3H,group.