聚乙烯醇/二氧化硅互穿网络膜的研究

采用溶胶凝胶法制备了聚乙烯醇/二氧化硅有机/无机互穿网络结构。扫描电子显微镜(SEM)观察到样品表面光滑,均匀;原子力显微镜(AFM)观察到样品中无机相与有机相呈互穿网络结构,且随无机物的增多两相分布更均匀;元素分析结果为纯PVA中w(O)为38%,随着无机物的增多w(O)逐渐降低为24.9%,是硅羟基与醇羟基之间脱去水,两相之间进行交联的结果;29SiNMR表明随无机物的增多,化学位移Q3的强度有所降低而化学位移Q4值却略有上升,说明硅羟基含量逐渐减少,两相交联程度逐渐增大,与元素分析结果相印证;热重曲线(TG)表明,无机物的加入使PVA的热降解温度由400℃提高到420℃,进一步证明两相之间已形成网状结构。

Study of Novel PVA/SiO2 Interpenetrating Polymer Network Membranes

Organic/inorganic interpenetrating polymer network (IPN) was prepared through sol-gel reaction of poly(vinyl alcohol)(PVA) with tetraethylorthosilicate (TEOS).The structure of the PVA/TEOS membranes was characterized by scanning electron microscopy (SEM),atomic force microscope (AFM),energy dispersive spectroscopy (EDX),elementary analysis and 29Si-NMR.The SEM micrographs showed the surface of membranes to be uniform and homogeneous.AFM indicated that there is good compatibility in the system due to the resulting cross-linked network of organic and inorganic phases.w(O)% of PVA/SiO2IPN decreases from 38%(as in pure PVA) to 24.9%,indicating the condensation reaction between Si—OH groups from hydrolyzed TEOS and C—OH groups from PVA.It was also established by 29Si-NMR that the intensity of Q3 decreases,but the intensity of Q4 increases.The thermal property of PVA/SiO2 IPN was examined by thermogravimetric analysis (TGA).The decomposition temperature of the main chain is raised from 400 ℃ to 420 ℃.The PVA/SiO2 IPN exhibits high thermal stability,which suggests that some kind of bonds is formed between PVA and SiO2 and enhances the thermal stability of the materials.