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Synthesis of arborescent model polymer structures by living carbocationic polymerization for structure-property studies.

机译：通过活性碳阳离子聚合合成树状模型聚合物结构，用于结构性质研究。

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Polyisobutylene is fully saturated, therefore exhibits outstanding chemical, oxidative and thermal stability,1 which makes it ideally suitable as a model to study mechanical and viscoelastic properties of elastomers, and to correlate properties with structure. The main objective of this dissertation was to develop a fundamental understanding of the mechanism of the synthesis of arborescent (hyperbranched) polyisobutylene (arbPIB) by inimer-type (initiator-monomer) living carbocationic polymerization.;The strategy for the effective synthesis of arbPIBs consists of copolymerizing the 4-(2-methoxyisopropyl)styrene (IUPAC name: p-vinylcumyl methyl ether) (IB) via controlled/living carbocationic polymerization using TiCl4 coinitiator. In situ FTIR monitoring showed that the self-condensing vinyl polymerization (SCVP) of MeOIM is possible, and that when copolymerizing MeOIM and IB, a nearly alternating structure and multiple end groups are obtained. arbPIB was synthesized and the repeatability of the polymerization was demonstrated. It was found that higher branching was obtained with increasing [MeOIM] and that branching did not further increase if additional IB was added after the MeOIM had reacted completely. No evident changes were observed when switching solvents from Hx/MeCl to a MeCHx/MeCl mixture. Branching parameters showed that arbPIBs have a behavior between polydisperse stars and polycondensates with the number of branches increasing linearly with molecular weight.;Novel arbPIB-based block copolymers (TPEs) were synthesized and it was found that copolymers with low Tg short end blocks and less than 5 mol% of a second monomer exhibit thermoplastic elastomeric properties. The materials were strongly reinforced when compounded with carbon black.;arbPIB-b-PS are prospective biomaterials and the establishment of reliable methods for evaluating their short and long term properties is a subject of great importance. A dynamic fatigue testing methodology was developed for small, soft rubbery specimens that can be implanted into small animals and re-tested after explantation. Higher ultimate tensile strength and lower elongation at break were measured on microdumbbells than on standard dumbbells. Fatigue testing microdumbbells induced higher stresses at the same strain rate, thus presenting the worst case scenario and being appropriate for fatigue tests.;The fatigue limit of linear polystyrene-b-polyisobutylene- b-polystyrene (SIBS) and analogous arbPIB- b-PS samples were determined by using stepwise increasing strain tests developed for fatigue analysis. The presence of branching and a broader molecular weight distribution arbPIB-b-PS led to better mechanical stability and higher fatigue limit than in analogous linear SIBS samples.
机译：聚异丁烯是完全饱和的，因此具有出色的化学，氧化和热稳定性，1因此非常适合用作研究弹性体的机械和粘弹性特性以及将特性与结构关联的模型。本论文的主要目的是对通过亚胺型（引发剂-单体）活性碳阳离子聚合反应合成树状（超支化）聚异丁烯（arbPIB）的机理有一个基本的了解。通过使用TiCl 4共引发剂的受控/活性碳阳离子聚合将4-（2-甲氧基异丙基）苯乙烯（IUPAC名称：对乙烯基枯基甲基醚）（IB）进行共聚合的方法。现场FTIR监测表明，MeOIM的自缩乙烯基聚合（SCVP）是可能的，并且当MeOIM和IB共聚时，可获得近乎交替的结构和多个端基。合成了arbPIB，并证明了聚合的可重复性。发现随着[MeOIM]的增加获得更高的支化，并且如果在MeOIM完全反应后添加额外的IB，则支化不会进一步增加。当将溶剂从Hx / MeCl切换到MeCHx / MeCl混合物时，没有观察到明显的变化。支化参数表明，arbPIBs在多分散星和缩聚物之间具有行为，支链数随分子量线性增加。;合成了新颖的基于arbPIB的嵌段共聚物（TPEs），发现该共聚物具有较低的Tg短端嵌段和较少的嵌段共聚物小于5mol％的第二单体表现出热塑性弹性体性能。当与炭黑混合时，这些材料被强力增强。； arbPIB-b-PS是潜在的生物材料，建立评估其短期和长期性能的可靠方法非常重要。开发了一种动态疲劳测试方法，用于小的，柔软的橡胶状标本，可以将其植入小型动物中，并在植入后进行重新测试。与标准哑铃相比，在微型哑铃上测得更高的极限拉伸强度和更低的断裂伸长率。疲劳测试微哑铃在相同的应变率下会产生更高的应力，因此是最坏的情况，适合疲劳测试。线性聚苯乙烯-b-聚异丁烯-b-聚苯乙烯（SIBS）和类似的arbPIB-b-PS的疲劳极限通过为疲劳分析开发的逐步增加的应变测试来确定样品。与类似的线性SIBS样品相比，存在分支和较宽的分子量分布arbPIB-b-PS导致更好的机械稳定性和更高的疲劳极限。

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