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二乙烯三胺及其衍生物在ATRP中作用的研究
The Investigation of Diethylenetriamine and Its Derivatives Effect on ATRP
【作者】 杨俊；
【导师】 张可达；
【作者基本信息】 苏州大学 ， 应用化学， 2010， 硕士
【摘要】 本论文主要讨论了DETA及其衍生物对于原子转移自由基聚合（ATRP）的影响,本论文主要包括三个部分:1. PMDETA及MA5-DETA作为还原剂的AGET-ATRP本文在使用ATRP引发剂EBiB/MBP/DCT作引发剂, PMDETA或MA5-DETA作配体,分别在高价金属催化剂CuCl2·2H2O和FeCl3·6H2O存在下能够引发MMA进行聚合,并且经过一段时间的诱导期后能够得到分子量可控的聚合物.通过空白实验的对照我们可以知道: MMA必须在EbiB, DCT或MBP等引发剂、高氧化态过渡金属卤化物和配体同时存在下,才能以合适的速度聚合,并得到分子量分布窄的聚合产物.其机理可表示如下:实验结果表明:在聚合体系中一部分PMDETA或者MA5-DETA作为还原剂,能够还原聚合体系中的Cu[Ⅱ]得到一部分Cu[Ⅰ],从而引发R-X产生自由基R? ,进行原子转移自由基聚合.2.有氧条件下的AGET-ATRP正常的ATRP需要在无氧的环境下进行,我们发现在使用CuCl作催化剂, MA3-DETA作配体时,在有氧气存在的条件下也能够得到分子量分布可控的聚合物,与无氧条件下得到的聚合物并无多大的差别;而且其动力学和扩链都符合活性聚合的特征.这样可以使正常的ATRP体系在有氧气存在下进行,并且得到分子量可控的聚合物.在存在氧气的条件下,使用DETA作为还原剂时,在适当的配比条件下能够得到分子量分布很窄的聚合物,对其进行动力学研究和扩链反应,整个聚合体系符合活性聚合的特点.3. DETA及其衍生物作为添加剂对ATRP的影响不同的多胺配体对反向原子转移自由基聚合有较大影响,使用MA3-DETA的聚合速度最快,除去DETA,其中从一取代到五取代的络合剂分子量以及分子量分布呈递减的趋势,说明取代基越多,可控性更好.当在反应前加入PMDETA时,使聚合速度减慢,同时能够很好的起到控制分子量分布的速度;在体系中加入DETA时,聚合速度反而加快,分子量增大,分子量分布变宽;当加入的物质变成MA3-DETA时,聚合速度加快,分子量分布先增大后减小.在反应过程中加入MA3-DETA或DETA时能够在短时间内增大转化率.由于DETA或MA3-DETA中存在的活泼H,能够还原CuⅡ,使得体系中自由基浓度的增大,从而影响聚合速度和分子量分布,而PMDETA的还原能力并不强,主要起到络合金属离子的作用,随着络合剂的增多,聚合会体现出更好的可控性.
【Abstract】 The thesis contains three parts that research the effect of diethylenetriamine and its derivatives on atom transfer radical polymerization:1. AGET ATRP of methyl methacrylate with PMDETA or MA5-DETA as reducing agentActivator generated by electron transfer atom transfer radical polymerization of methyl methacrylate （MMA） with air-stable Cu（II）X2（X=Br, Cl） as the catalyst and PMDETA or MA5-DETA as both ligand and reducing agent was investigated. Well-controlled PMMA with low PDI was prepared in the presence of Cu（II） and nitrogen-based ligands without any additional reducing agent. The molecular weight distribution of the resulting polymer was rather narrow （Mw/Mn =1.10-1.20） and the system showed good controllability. Chain extension of PMMA with MMA was successful, resulting in low-PDI PMMA and demonstrating well-maintained end-group functionality.By contrast to the blank assay, we found methyl methacrylate will not polymerize or be in a slowly reaction rate in the absence of Cu（II）, initiator or ligand. Nitrogen-based ligands can serve as reducing agents, reduce Cu（II） to Cu（I） for AGET ATRP, as well as ligands. Effects of the PMDETA and MA5-DETA content and the catalysts on polymerization were also investigated, respectively. 2. AGET ATRP of methyl methacrylate in the presence of oxygenThe normal atom transfer radical polymerization needs an anhydrous and oxygen free condition. When polymerization catalyzed by CuCl/MA3-DETA, Well-controlled poly （methyl methacrylate） was prepared in the presence of oxygen. By contrast to the resulting polymer in the oxygen free condition, the molecular weight and polydispersity had no changes much. Chain extension of PMMA with MMA was successful, resulting in low-PDI PMMA and demonstrating well-maintained end-group functionality.AGET ATRP of MMA with Cu（Ⅱ） as catalyst, PMDETA or MA5-DETA as ligand and diethylenetriamine as reducing agent. The molecular weight distribution of the resulting polymer was rather narrow （PDI=1.24）, and the dynamics research and chain extension reaction indicated the CuX2/PMDETA/DETA/Initiator system is a living radical polymerization.3. The effect of diethylenetriamine and its derivatives as additives on ATRP Considering DETA has five living H and the MA5-DETA is a good ligand, the effect of ligand with different number of living H on ATRP is studied. It is found that the polymerization is greatly effected by ligands （MAn-DETA） with different number of living H. A system with MA3-DETA as ligand processed the fastest reaction rete; the other one with MA5-DETA as ligand showed the best controllability.When DETA, MA3-DETA and PMDETA was added in the normal ATRP before reaction, the resulting polymer molecular weight and polydispersity will have big changes; When DETA and MA3-DETA is added into the polymerization system in the reaction period, the molecular weight of the resulting polymer will increase in different degrees. The polydispersity of the resulting polymer with DETA had a big change. The comparison among 1H-NMR of the resulting polymers indicated the polymer did not react with additives, the reason of acceleration was the additives reduced Cu（II） to Cu（I）, then caused radical concentration had a instantaneous increase.