ARGET ATRP法制备氮氧自由基聚合物刷及其应用研究

发布时间：2018-06-23 09:16

本文选题：氮氧自由基聚合物刷 + 醇选择性氧化　；参考：《河北科技大学》2016年硕士论文

【摘要】：2,2,6,6-四甲基哌啶-N-氧自由基(TEMPO)是一种稳定的自由基,有很多潜在的应用价值。其中,TEMPO作为催化剂应用在醇的选择性催化氧化过程中,表现出反应条件温和、活性高和选择性高等优点。另一方面其毒性小,可以作为高效的阻聚剂。但是TEMPO价格偏高,反应后难以回收,是其广泛应用的瓶颈。将TEMPO负载到载体上,实现其多次循环使用,是将其进行大规模应用的有效方法。本文首先以交联聚苯乙烯微球(PS)为基质,甲基丙烯酸甲酯(MMA)、甲基丙烯酸缩水甘油酯(GMA)和2,2,6,6-四甲基-4-哌啶基甲基丙烯酸酯(TMPM)为功能单体,利用表面引发电子转移活化再生催化剂原子转移自由基聚合(ARGET ATRP)法成功制得不同链结构聚合物刷,包括均聚物刷PS-PMMA、PS-PGMA和PS-PTMPM;嵌段共聚物刷PS-P(MMA-b-TMPM)和PS-P(MMA-b-GMA);无规共聚物刷PS-P(MMA-co-TMPM)。然后利用氧化法和开环法制备含有TEMPO结构单元的聚合物刷。氧化法是通过3-氯过氧苯甲酸(mCPBA)将TMPM的哌啶基氧化为氮氧自由基,分别制备了均聚物刷PS-PTMA、嵌段共聚物刷PS-P(MMA-b-TMA)、无规共聚物刷PS-P(MMA-co-TMA)。开环法是利用聚合物刷PS-PGMA和PS-P(MMA-b-GMA)上含有大量环氧基团与4-羟基-2,2,6,6-四甲基哌啶氮氧自由基(4-OH-TEMPO)的羟基间的开环成醚反应,制得含氮氧自由基的PS-PGMA-TEMPO均聚物刷和PS-P(MMA-b-GMA-TEMPO)嵌段共聚物刷。最后将氧化法制得的氮氧自由基聚合物刷作为催化剂应用在醇的选择性催化氧化中,探索了聚合物刷在两种醇的选择性催化氧化体系中的催化规律及催化机理,发现氮氧自由基聚合物刷的催化性能优于氮氧自由基聚合物链,具有催化性能高、循环使用性能好等优点。将开环法制得的氮氧自由基聚合物刷作为阻聚剂应用在合成环氧大豆油丙烯酸酯中,阻聚效果良好,且通过过滤即可将其回收。进而将聚合物刷阻聚剂与小分子阻聚剂4-OH-TEMPO组成复合阻聚体系,反应后回收出聚合物刷,剩余的小分子阻聚剂留在体系中,满足了反应和贮存过程中对阻聚剂的不同需求量。所有类型的聚合物刷都进行了6次以上循环测试,发现多次循环使用后酯化率基本不变,循环使用性能良好。
[Abstract]:Tetramethylpiperidine-N- (TEMPO) is a stable free radical and has many potential applications. The application of tempo as catalyst in the selective catalytic oxidation of alcohols shows the advantages of mild reaction conditions, high activity and high selectivity. On the other hand, its toxicity is small, can be used as an effective inhibitor. However, the high price of TEMPO, which is difficult to recover after reaction, is the bottleneck of its wide application. It is an effective method to load TEMPO on the carrier and to recycle it for many times. Firstly, crosslinked polystyrene microspheres (PS) were used as functional monomers, methyl methacrylate (MMA), glycidyl methacrylate (GMA) and TMPM were used as functional monomers. Atom transfer radical polymerization (ARGET ATRP) was used to prepare different chain structure polymer brushes, including homopolymer brushes PS-PMMA-PS-PGMA and PS-PTMPM; block copolymers PS-P (MMA-b-TMPM) and PS-P (MMA-b-GMA); random copolymers brush PS-P (MMA-co-TMPM). Then polymer brushes containing TEMPO structure units were prepared by oxidation and ring opening methods. PS-PTMA-block copolymers (MMA-b-TMA) and random copolymers (PS-P (MMA-co-TMA) were prepared by oxidation of the piperidinyl group of TMPM to nitroxyl radical by 3-chloro peroxy benzoic acid (mCPBA), and block copolymers PS-P (MMA-b-TMA) and random copolymers PS-P (MMA-co-TMA) were prepared respectively. The ring opening reaction of PS-PGMA and PS-P (MMA-b-GMA) containing a large number of epoxide groups on polymer brushes was used to form ethers between the hydroxyl groups of 4-OH-TEMPO radical (4-OH-TEMPO) and PS-PGMA-TEMPO block copolymers of PS-PGMA-TEMPO (MMA-b-GMA-TEMPO) block copolymers of PS-PGMA-TEMPO (MMA-b-GMA-TEMPO) block brushes. Finally, the nitrogen-oxygen radical polymer brush was used as a catalyst in the selective catalytic oxidation of alcohol, and the catalytic law and mechanism of the polymer brush in the system of selective catalytic oxidation of two alcohols were explored. It is found that the catalytic performance of nitroxyl radical polymer brush is better than that of nitroxyl radical polymer chain, which has the advantages of high catalytic performance and good recycle performance. The nitrogen-oxygen radical polymer brush prepared by ring-opening method was used as an inhibitor in the synthesis of epoxy soybean oil acrylate. The polymerization inhibition effect was good and it could be recovered by filtration. Then the polymer brush inhibitor and the small molecular inhibitor 4-OH-TEMPO were used to form a composite polymer inhibitor system, and the polymer brush was recovered after the reaction. The remaining small molecular inhibitor remained in the system, which satisfied the different demand for the inhibitor in the reaction and storage process. All kinds of polymer brushes were tested for more than 6 cycles. It was found that the esterification rate was basically unchanged and the recycling performance was good.
【学位授予单位】：河北科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O631.3

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