AM2Net Advanced Macromolecular Materials By Transition Metal Catalysis; Group 3: "Ring-opening Polymerization Catalysis"; Alkaline-earth (and lanthanide) metal-alkoxide catalysts for oxygenate polymerization

AM2Net 过渡金属催化先进高分子材料；

• 批准号: 5404737
• 负责人: Professor Dr. Sjoerd Harder
• 金额: --
• 依托单位: Lehrstuhl für Anorganische und Metallorganische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2003
• 资助国家: 德国
• 起止时间: 2002-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5404737?language=en
• 关键词: AM2Net; Advanced; Macromolecular; Materials; Transition

Industrially, there is an increasing interest in the development of new polymeric materials from classical monomers. During the last decade of polymer research, the keyword in the rational design of new materials from "old" monomers has been stereoselective polymerisation. The last few years, however, there is an increasing tendency in designing new materials by means of copolymerisation. Many research groups concentrate on statistical copolymerisation of monomer mixtures as a way to influence the physical properties of the polymer. We like to concentrate on a very powerful method in rational polymer design: block-copolymerization. In order to achieve the syntheses of block-copolymers the polymerization reactions need to be living. Therefore, block-copolymers are traditionally prepared by anionic polymerisation using alkalimetal alkyls as initiator. It is our aim to combine the advantages of living block-copolymerisation with those of stereoselektive polymerisation. Preliminary work of our group has shown that this goal can be reached partially by the use of divalent alkaline-earth initiators. These complexes polymerize styrene in a living fashion with syndiotacticities up to r = 91%. We could show that the remaining errors are due to inversion of the chiral chain-end, which leads to racemisation of the stereocenters. One approach to retard these chain-end inversions is the use of initiators with trivalent metals: the bond between polymer chain and metal is stronger and this leads to slower inversion. We therefore like to extend our research with the syntheses of trivalent metal initiators that are isolobal to the divalent alkaline-earth initiators. There are two possible approaches that will be pursued: i) the use of isolobal cationic initiators and ii) the use of isolobal neutral initiators with dianionic ligand systems. The metall will be preferably aluminium for which recently considerable potential in alkene polymerisation has been shown. We also like to venture into lanthanide metal chemistry, which has been shown quite useful in polymerisation catalyses lately. Apart from the syntheses and structures of new catalysts based on trivalent metals, the polymerization properties and especially their mechanisms will be investigated as well. We like to concentrate especially on the block-copolymers of styrene and butadiene. It is expected that stereoregular styrene blocks within atactic butadiene blocks will result in elastomeric materials that are transparent and have an unusual high impact.

在工业上，人们对从经典单体开发新型聚合物材料越来越感兴趣。在过去十年的聚合物研究中，从“旧”单体合理设计新材料的关键词是立体选择性聚合。然而，最近几年，通过共聚来设计新材料的趋势日益明显。许多研究小组专注于单体混合物的统计共聚，以此作为影响聚合物物理性能的一种方式。我们喜欢关注理性聚合物设计中一种非常强大的方法：嵌段共聚。为了实现嵌段共聚物的合成，聚合反应必须是活跃的。因此，嵌段共聚物传统上是通过使用碱金属烷基化物作为引发剂的阴离子聚合来制备的。我们的目标是将活性嵌段共聚与立体选择性聚合的优点结合起来。我们小组的初步工作表明，通过使用二价碱土引发剂可以部分实现这一目标。这些配合物以活性方式聚合苯乙烯，间同立构规整度高达 r = 91%。我们可以证明，剩余的错误是由于手性链末端的反转造成的，这导致立体中心的外消旋化。延迟这些链端反转的一种方法是使用三价金属引发剂：聚合物链和金属之间的键更强，这会导致更慢的反转。因此，我们希望通过合成与二价碱土引发剂同花的三价金属引发剂来扩展我们的研究。将采用两种可能的方法：i) 使用同位素阳离子引发剂和 ii) 使用同位素中性引发剂与双阴离子配体系统。该金属优选是铝，最近铝在烯烃聚合中已显示出相当大的潜力。我们还喜欢冒险进入镧系金属化学领域，最近它在聚合催化中被证明非常有用。除了基于三价金属的新型催化剂的合成和结构外，还将研究聚合性能，特别是其机理。我们特别关注苯乙烯和丁二烯的嵌段共聚物。预计无规丁二烯嵌段内的有规立构苯乙烯嵌段将产生透明且具有异常高冲击力的弹性体材料。