可溶液加工的聚(多金属氧簇降冰片烯)和聚(己酸降冰片烯)嵌段和无规共聚物的合成及催化功能的研究

Synthesis of Solution-processable Block and Random Copolymers of Poly(polyoxometalate norbornene) and Poly(hexanoic acid norbornene) and Study on their Catalytic Activity

将一种可有机功能化的Wells-Dawson POM与降冰片烯相连接,制备了多金属氧簇降冰片烯单体.再利用活性可控的开环易位聚合方法(ROMP),在Grubbs 3^(rd)催化剂的作用下,合成了聚(多金属氧簇降冰片烯)-聚(己酸降冰片烯)的杂化嵌段和无规共聚物(H-CPs),分别简写为Poly(POM)_m-b-Poly(COOH)_n和Poly(POM)_m-r-Poly(COOH)_n.采用~1H-NMR、^(31)P-NMR和FTIR等方法对共聚物结构进行表征,确认我们成功地合成了由共价键连接这2种单体形成的H-CPs.最后,利用带有光散射和红外探测器的凝胶渗透色谱(SEC)测定聚合物的绝对分子量和分子量分布,证明所得到的H-CPs不仅分子量可控,而且分子量分布系数较窄.最后,研究了H-CPs催化氧化四氢噻吩(THT)成环丁亚砜(THTO)反应,结果表明,相比于聚(多金属氧簇)的均聚物(Poly(POM)),H-CPs的催化活性有所下降,原因是POM催化剂含量较低以及H-CPs在催化介质中溶解性的差异.

Polyoxometalates（abbreviated as POM）, are a class of anionic metal-oxygen clusters, which consist of early transition metals in their highest oxidation states. Thus they show excellent catalytic function. In the past years we have concentrated on synthesizing POM-containing polymers, so-called poly（polyoxometalate）s, to obtain a class of novel organic-inorganic hybrid materails with good processabililty and mechnical properties of organic polymers and catalytic function of inorganic POM clusters. We connected an organic-functionalized Wells-Dawson POM with norbornene to prepare a POM-containing norbornene monomer. Then, using the ring-opening metathesis polymerization（ROMP） approach, hybrid block and random copolymers of poly（POM norbornene） and poly（hexanoic acid norbornene）（denoted as Poly（POM）m-b-Poly（COOH）n） and Poly（POM）mr-Poly（COOH）n） were synthesized in the presence of Grubbs 3^rd catalyst. These copolymers thus prepared included block copolymers with m = 5 and n = 50, 100, 200 and 300, as well as a random copolymer with m = 5 and n = 100, i.e., Poly（POM）5-r-Poly（COOH）100. The chemical structures of these hybrid copolymers were characterized by ^1H-NMR, ^31P-NMR and FTIR. The characterization results indicated that all the copolymers were successfully synthesized. Their absolut molecular weights and polydispersity indexes were determined by size exclusion chromatography（SEC） equipped with light scattering and infrared detectors. The results indicated that the molecular weights of the obtained hybrid copolymers were well-controlled with narrow molecular weight distribution coefficient. These hybrid copolymers were solution-processable. Their solid samples, prepared from their solution, were flexible. These hybrid copolymers also demonstrtated the catalytic activity of the parent POM cluster. The study on their capacity in catalytic oxidation of tetrahydrothiophene（THT） into cyclobutylsulfoxide（THTO） showed that their catalytic efficiencies were lower than that the hybrid homopolymer, poly（polyoxometalate） and decreased with increasing length of Poly（COOH） blocks. The findings obtained in this study offer a competitive strategy for developing novel hybrid materials with both functions of inorgnaic compnents and mechanical properties and pocessebility of the organic polymers.